Survival of O157 and non-O157 shiga toxin-producing Escherichia coli in Korean style kimchi

Korean style kimchi contaminated with Shiga toxin-producing Escherichia coli (STEC) O157:H7 was the cause of an outbreak in Canada from December 2021 to January 2022. To determine if this STEC O157:H7 has greater potential for survival in kimchi than other STEC, the outbreak strain and six other STEC strains (O26:H11, O91:H21, O103:H2, O121:H19, and two O157:H7) were inoculated individually at 6 to 6.5 log CFU/g into commercially sourced kimchi and incubation at 4 °C. At intervals of seven days inoculated and control kimchi was plated onto MacConkey agar to enumerate lactose utilising bacteria. The colony counts were interpreted as enumerating the inoculated STEC, since no colonies were observed on MacConkey agar plated with uninoculated kimchi. Over eight weeks of incubation the pH was stable at 4.10 to 4.05 and the STEC strains declined by 0.7-1.0 log, with a median reduction of 0.9 log. The linear rate of reduction of kimchi outbreak STEC O157:H7 was -0.4 log per 30 days (Slope Uncertainty 0.05), which was not significantly different from the other O157 and nonO157 STEC strains (P = 0.091). These results indicate that the outbreak was not due to the presence of strain better adapted to survival in kimchi than other STEC, and that STEC can persist in refrigerated Korean style kimchi with a minimal decline over the shelf-life of the product.

Effect of yeast extract on microbiologically influenced corrosion of X70 pipeline steel by Desulfovibrio bizertensis SY-1

Microbiologically influenced corrosion (MIC) is a complicated process that happens ubiquitously and quietly in many fields. As a useful nutritional ingredient in microbial culture media, yeast extract (YE) is a routinely added in the MIC field. However, how the YE participated in MIC is not fully clarified. In the present work, the effect of YE on the growth of sulfate reducing prokaryotes (SRP) Desulfovibrio bizertensis SY-1 and corrosion behavior of X70 pipeline steel were studied. It was found that the weight loss of steel coupons in sterile media was doubled when YE was removed from culture media. However, in the SRP assays without YE the number of planktonic cells decreased, but the attachment of bacteria on steel surfaces was enhanced significantly. Besides, the corrosion rate of steel in SRP assays increased fourfold after removing YE from culture media. MIC was not determined for assays with planktonic SRP but only for biofilm assays. The results confirm the effect of YE on D. bizertensis SY-1 growth and also the inhibitory role of YE on MIC.

Stress resistant rpsU variants of Listeria monocytogenes can become underrepresented due to enrichment bias

Population heterogeneity is an important component of the survival mechanism of Listeria monocytogenes, leading to cells in a population with diverse stress resistance levels. We previously demonstrated that several ribosomal gene rpsU mutations enhanced the stress resistance of L. monocytogenes and lowered the growth rate at 30 °C and lower temperatures. This study investigated whether these switches in phenotypes could result in a bias in strain detection when standard enrichment-based procedures are applied to a variety of strains. Detailed growth kinetics analysis of L. monocytogenes strains were performed, including the LO28 wild type (WT) and rpsU variants V14 and V15, during two commonly used enrichment-based procedures described in the ISO 11290-1:2017 and the U.S. Food and Drug Administration Bacteriological Analytical Manual (BAM). WT had a higher growth rate than the variants during the enrichment processes. Co-culture growth kinetics predictions for WT and rpsU variants showed that the detection chances of the rpsU mutants were reduced from ∼52 % to less than ∼13 % and ∼ 3 % during ISO and BAM enrichment, respectively, which were further validated through subsequent qPCR experiments. Higher heat stress resistance of rpsU variants did not lead to faster recovery during enrichment after heat treatment, and different pre-culturing temperatures before heat treatment did not significantly affect the growth kinetics of the WT and rpsU variants. Additionally, post-enrichment isolation procedures involving streaking on selective agar plates did not show preferences for isolating WT or rpsU variants nor affect the detection chance of rpsU variants. The difference in detection chance suggests that the selective enrichment procedures inadequately represent the genotypic diversity present in a sample. Hence, the enrichment bias during the L. monocytogenes isolation procedure may contribute to the observed underrepresentation of the rpsU mutation among L. monocytogenes isolates deposited in publicly available genome databases. The underrepresentation of rpsU mutants in our findings suggests that biases introduced by standard isolation and enrichment procedures could inadvertently skew our understanding of genetic diversity when relying on public databases.

The impact of different acidic conditions and food substrates on Listeria monocytogenes biofilms development and removal using nanoencapsulated carvacrol

Listeria monocytogenes biofilms present a significant challenge in the food industry. This study explores the impact of different acidic conditions of culture media and food matrices on the development and removal of biofilms developed on stainless steel surfaces by wild-type (WT) L. monocytogenes strains as well as in two mutant derivatives, ΔsigB and ΔagrA, that have defects in the general stress response and quorum sensing, respectively. Additionally, the study investigates the efficacy of nanoencapsulated carvacrol as an antimicrobial against L. monocytogenes biofilms developed in Tryptic Soy Broth (TSB) culture media acidified to different pH conditions (3.5, 4.5, 5.5, 6.5), and in food substrates (apple juice, strained yogurt, vegetable soup, semi-skimmed milk) having the same pH levels. No biofilm formation was observed for all L. monocytogenes strains at pH levels of 3.5 and 4.5 in both culture media and food substrates. However, at pH 5.5 and 6.5, increased biofilm levels were observed in both the culture media and food substrates, with the WT strain showing significantly higher biofilm formation (3.04-6.05 log CFU cm-2) than the mutant strains (2.30-5.48 log CFU cm-2). For both applications, the nanoencapsulated carvacrol demonstrated more potent antimicrobial activity against biofilms developed at pH 5.5 with 2.23 to 3.61 log reductions, compared to 1.58-2.95 log reductions at pH 6.5, with mutants being more vulnerable in acidic environments. In food substrates, nanoencapsulated carvacrol induced lower log reductions (1.58-2.90) than the ones in TSB (2.02-3.61). These findings provide valuable insights into the impact of different acidic conditions on the development of L. monocytogenes biofilms on stainless steel surfaces and the potential application of nanoencapsulated carvacrol as a biofilm control agent in food processing environments.

Bacitracin agar vs. oleandomycin disk supplemented chocolate agar for the recovery of Haemophilus influenzae in diagnostic samples: A prospective comparison

Haemophilus influenzae is an important pathogen able to cause various forms of respiratory and invasive disease. To provide high sensitivity for detection, culture media must inhibit growth of residential flora from the respiratory tract. This study aimed to identify and compare the diagnostic and economic advantages of using bacitracin containing selective agar (SEL) or oleandomycin disk supplemented chocolate agar (CHOC). Growth and semi-quantitative abundance of H. influenzae and growth suppression of residential flora was prospectively assessed in a 28-week period. H. influenzae was identified in 164 (5 %) of all included samples: CHOC and SEL, CHOC only, and SEL only were positive in 95, 24, and 45 cases. Diagnostic superiority of SEL was primarily attributable to the results of throat swabs. However, on average, € 200 had to be spent for the detection of each additional isolate that was recovered only because of additional incubation on SEL.

Growth assessment of Salmonella enterica multi-serovar populations in poultry rinsates with commonly used enrichment and plating media

Isolation of Salmonella from enrichment cultures of food or environmental samples is a complicated process. Numerous factors including fitness in various selective enrichment media, relative starting concentrations in pre-enrichment, and competition among multi-serovar populations and associated natural microflora, come together to determine which serovars are identified from a given sample. A recently developed approach for assessing the relative abundance (RA) of multi-serovar Salmonella populations (CRISPR-SeroSeq or Deep Serotyping, DST) is providing new insight into how these factors impact the serovars observed, especially when different selective enrichment methods are used to identify Salmonella from a primary enrichment sample. To illustrate this, we examined Salmonella-positive poultry pre-enrichment samples through the selective enrichment process in Tetrathionate (TT) and Rappaport Vassiliadis (RVS) broths and assessed recovery of serovars with each medium. We observed the RA of serovars detected post selective enrichment varied depending on the medium used, initial concentration, and competitive fitness factors, all which could result in minority serovars in pre-enrichment becoming dominant serovars post selective enrichment. The data presented provide a greater understanding of culture biases and lays the groundwork for investigations into robust enrichment and plating media combinations for detecting Salmonella serovars of greater concern for human health.

Mircrofabricating double-sided polydimethylsiloxane (PDMS) artificial phylloplane for microbial food safety research

Leafy green surface microbiology studies often experience significant variations in results due to the heterogeneous nature of leaf surfaces. To provide a precise and controllable substitute, we microfabricated double-sided artificial leafy green phylloplanes using polydimethylsiloxane (PDMS) with a vinyl-terminated polyethylene glycol chain-based hydrophobicity modifier (PDMS-PEG) to modify PDMS hydrophobicity. We further tested the properties and applications of these artificial leaves, by examining the function of epicuticular wax, growth and survival of E. coli O157:H7 87-23 on the surface, and removal of attached E. coli cells via sanitation. The double-sided PDMS-PDMS-PEG leaves well-replicated their natural counterparts in macroscopic and microscopic structure, hydrophobicity, and E. coli O157:H7 87-23 attachment. After depositing natural epicuticular wax onto artificial leaves, the leaf surface wetting ability decreased, while E. coli O157:H7 87-23 surface retention increased. The artificial leaves supplied with lettuce lysate or bacterial growth media supported E. coli O157:H7 87-23 growth and survival similarly to those on natural leaves. In the sanitation test, the artificial lettuce leaves also displayed patterns similar to those of natural leaves regarding sanitizer efficiency. Overall, this study showcased the microfabrication and applications of double-sided PDMS-PDMS-PEG leaves as a replicable and controllable platform for future leafy green food safety studies.

Enhanced production of mycelium biomass and exopolysaccharides of Pleurotus ostreatus by integrating response surface methodology and artificial neural network

This study aimed to enhance the production of mycelium biomass and exopolysaccharides (EPS) of Pleurotus ostreatus in submerged fermentation. Response Surface Methodology (RSM)sought to optimize culture conditions, whereas Artificial Neural Network (ANN)aimed to predict the mycelium biomass and EPS. After optimization of RSM model conditions, the maximum biomass (36.45 g/L) and EPS (6.72 g/L) were obtained at the optimum temperature of 22.9 °C, pH 5.6, and agitation of 138.9 rpm. Further, the Genetic Algorithm (GA) was employed to optimize the cultivation conditions in order to maximize the mycelium biomass and EPS production. The ANN model with an optimized network structure gave the coefficient of determination (R2) value of 0.99 and the least mean squared error of 1.9 for the validation set. In the end, a graphical user interface was developed to predict mycelium biomass and EPS production.

Lipid-Restricted Culture Media Reveal Unexpected Cancer Cell Sensitivities

Cancer cell culture models frequently rely on fetal bovine serum as a source of protein and lipid factors that support cell survival and proliferation; however, serum-containing media imperfectly mimic the in vivo cancer environment. Recent studies suggest that typical serum-containing cell culture conditions can mask cancer dependencies, for example, on cholesterol biosynthesis enzymes, that exist in vivo and emerge when cells are cultured in media that provide more realistic levels of lipids. Here, we describe a high-throughput screen that identified fenretinide and ivermectin as small molecules whose cytotoxicity is greatly enhanced in lipid-restricted media formulations. The mechanism of action studies indicates that ivermectin-induced cell death involves oxidative stress, while fenretinide likely targets delta 4-desaturase, sphingolipid 1, a lipid desaturase necessary for ceramide synthesis, to induce cell death. Notably, both fenretinide and ivermectin have previously demonstrated in vivo anticancer efficacy despite their low cytotoxicity under typical cell culture conditions. These studies suggest ceramide synthesis as a targetable vulnerability of cancer cells cultured under lipid-restricted conditions and reveal a general screening strategy for identifying additional cancer dependencies masked by the superabundance of medium lipids.

The responses of pepper plants to nitrogen form and dissolved oxygen concentration of nutrient solution in hydroponics

BACKGROUND

The presence of oxygen in the growth medium is absolutely essential for root development and the overall metabolic processes of plants. When plants do not have an adequate oxygen supply for respiration, they can experience a condition known as hypoxia. In order to investigate the impact of different nitrogen forms and varying oxygen levels in nutrient solutions on the growth, photosynthesis, and chlorophyll fluorescence parameters of bell pepper plants, a comprehensive study was conducted. The experiment was designed as a factorial experiment, considering two main factors: nitrogen forms (calcium nitrate and ammonium sulfate) with a fixed nitrogen concentration of 5 mM, and the oxygen levels of the nutrient solutions (ranging from 1.8 ± 0.2 to 5.3 ± 0.2 mg. L-1).

RESULTS

The study examined the effects of nitrogen (NH4+ and NO3-) application on various parameters of vegetative growth. The results demonstrated that the use of ammonium (NH4+) led to a reduction in the most measured parameters, including the fresh and dry mass of both the root and shoot, at low O2 concentrations of 1.8 ± 0.2; 2.6 ± 0.2 and 3.8 ± 0.2 mg. L-1. However, an interesting observation was made regarding the impact of oxygen levels on root growth in plants grown with nitrate (NO3-). Specifically, the highest levels of oxygen significantly increased root growth in NO3--fed plants. Additionally, the application of NH4+ resulted in an increase in chlorophyll concentration in the leaves, particularly when combined with high oxygen levels in the nutrient solution. On the other hand, leaves of plants fed with NO3- exhibited higher photosynthetic rate (A), intrinsic water use efficiency (iWUE), and instantaneous carboxylation efficiency (A/Ci) compared to those fed with NH4+. Furthermore, it was found that NO3--fed plants displayed the highest instantaneous carboxylation efficiency at oxygen levels of 3.8 and 5.3 mg. L-1, while the lowest efficiency was observed at oxygen levels of 1.8 and 2.6 mg. L-1. In contrast, NH4+-grown plants exhibited a higher maximal quantum yield of PSII photochemistry (Fv/Fm), as well as increased variable fluorescence (Fv) and maximum fluorescence (Fm), compared to NO3--grown plants. Interestingly, the NO3--fed plants showed an increase in Fv/Fm, Fv, and Fm with the elevation of oxygen concentration in the nutrient solution up to 5.3 mg. L-1.

CONCLUSION

This study showed that, the growth and photosynthesis parameters in bell pepper plants are sensitive to oxygen stress in floating hydroponic culture. Therefore, the oxygen level in the nutrient solution must not be lower than 3.8 and 5.3 mg. L-1 in NH4+ and NO3- -supplied culture media or nutrient solutions, respectively.

Using CHROMagar™ STEC medium exclusively does not recover all clinically relevant Shiga toxin-producing Escherichia coli in Aotearoa, New Zealand

Diagnostic laboratories in Aotearoa, New Zealand (NZ) refer cultures from faecal samples positive for Shiga toxin genes to the national Enteric Reference Laboratory for isolation of Shiga toxin-producing Escherichia coli (STEC) for epidemiological typing. As there was variation in the culture media being referred, a panel of 75 clinical isolates of STEC, representing 28 different serotypes, was used to assess six commercially available media and provide guidance to clinical laboratories. Recommendations were subsequently tested for a 3-month period, where STEC isolations and confirmations were assessed by whole genome sequencing analysis against the culture media referred. CHROMagar™ STEC (CH-STEC; CHROMagar Microbiology, Paris, France) or CH-STEC plus cefixime-tellurite sorbitol MacConkey agar was confirmed inferior to CH-STEC plus blood agar with vancomycin, cefsulodin, and cefixime (BVCC). The former resulted in fewer STEC types (n = 18) being confirmed compared to those from a combination of CH-STEC and BVCC (n = 42). A significant (P < .05) association with an STEC's ability to grow on CH-STEC and the presence of the ter gene cluster, and eae was observed. Culturing screen positive STEC samples onto both CH-STEC and BVCC ensures a consistently higher recovery of STEC from all clinical samples in NZ than CH-STEC alone.

Optimization of fermentation conditions and medium components for chrysomycin a production by Streptomyces sp. 891-B6

BACKGROUND

Chrysomycin A (CA) is a promising antibiotic for treatment of Gram-positive bacterial infections and cancers. In order to enhance CA yield, optimization of fermentation conditions and medium components was carried out on strain Streptomyces sp. 891-B6, an UV-induced mutant with improved CA titer compared with its wide-type marine strain 891.

RESULTS

Using one-way experiment, the optimal fermentation conditions for CA production in 1-L shake flask were obtained as follows: 12 days of fermentation time, 5 days of seed age, 5% of inoculum volume ratio, 200 mL of loading volume and 6.5 of initial pH. By response surface methodology, the optimal medium components determined as glucose (39.283 g/L), corn starch (20.662 g/L), soybean meal (15.480 g/L) and CaCO3 (2.000 g/L).

CONCLUSION

Validation tests showed that the maximum yield of CA reached 1601.9 ± 56.7 mg/L, which was a 60% increase compared to the initial yield (952.3 ± 53.2 mg/L). These results provided an important basis for scale-up production of CA by strain 891-B6.

Identification and antimicrobial susceptibility profile of bacteria isolated from primary endodontic infections

This study aimed to identify and characterize the antimicrobial susceptibility profile of bacteria found in primary endodontic infections in the teeth of patients treated at the Dental Clinic of the University of Ribeirão Preto, São Paulo, Brazil. From September to December 2019, samples were obtained from 21 patients with primary endodontic infections. The collections were carried out in triplicate using paper cones placed close to the total length of the root canal. Bacterial isolation was performed in Brain Heart Infusion agar, Blood agar, and other selective culture media cultured at 37°C for up to 48 h under aerobiosis and microaerophilic conditions. The bacterial species were identified using the Vitek 2 automated system. The disk diffusion method on agar Müeller-Hinton was used to assess antimicrobial susceptibility with the recommended antimicrobials for each identified bacterial species. A total of 49 antibiotics were evaluated. Fifteen of the 21 samples collected showed bacterial growth, and 17 bacterial isolates were found. There were 10 different bacterial species identified: Enterococcus faecalis (four isolates), Streptococcus mitis/oralis (three isolates), Streptococcus anginosus (three isolates) being the most common, followed by Staphylococcus epidermidis, Enterococcus faecium, Streptococcus constellatus, Streptococcus alactolyticus, Enterobacter cloacae, Klebsiella variicola, and Providencia rettgeri (one isolate of each species). The analysis demonstrated significant susceptibility to most of the tested antibiotics. However, some Enterococcus isolates resisted the antibiotic's erythromycin, ciprofloxacin, and tetracycline. A Staphylococcus epidermidis isolate was characterized as multidrug-resistant. Five Streptococcus isolates were non-susceptible to all antibiotics tested.

An interlaboratory study on the detection method for Escherichia albertii in food using real time PCR assay and selective agars

Escherichia albertii is an emerging enteropathogen. Although E. albertii-specific detection and isolation methods have been developed, their efficiency on food samples have not yet been systematically studied. To establish a series of effective methods for detecting E. albertii in food, an interlaboratory study was conducted in 11 laboratories using enrichment with modified E. coli broth supplemented with cefixime and tellurite (CT-mEC), real-time PCR assay, and plating on four kinds of selective agars. This study focused on the detection efficiency of an E. albertii-specific real-time PCR assay (EA-rtPCR) and plating on deoxycholate hydrogen sulfide lactose agar (DHL), MacConkey agar (MAC), DHL supplemented with rhamnose and xylose (RX-DHL), and MAC supplemented with rhamnose and xylose (RX-MAC). Chicken and bean sprout samples were inoculated with E. albertii either at 17.7 CFU/25 g (low inoculation level) or 88.5 CFU/25 g (high inoculation level), and uninoculated samples were used as controls. The sensitivity of EA-rtPCR was 1.000 for chicken and bean sprout samples inoculated with E. albertii at low and high inoculation levels. The Ct values of bean sprout samples were higher than those of the chicken samples. Analysis of microbial distribution by 16S rRNA gene amplicon sequencing in enriched cultures of bean sprout samples showed that approximately >96 % of the population comprised unidentified genus of family Enterobacteriaceae and genus Acinetobacter in samples which E. albertii was not isolated. The sensitivity of the plating methods for chicken and bean sprout samples inoculated with a high inoculation level of E. albertii was 1.000 and 0.848-0.970, respectively. The sensitivity of the plating methods for chicken and bean sprout samples inoculated with a low inoculation level of E. albertii was 0.939-1.000 and 0.515-0.727, respectively. The E. albertii-positive rate in all colonies isolated in this study was 89-90 % in RX-DHL and RX-MAC, and 64 and 44 % in DHL and MAC, respectively. Therefore, the sensitivity of RX-supplemented agar was higher than that of the agars without these sugars. Using a combination of enrichment in CT-mEC and E. albertii isolation on selective agars supplemented with RX, E. albertii at an inoculation level of over 17.5 CFU/25 g of food was detected with a sensitivity of 1.000 and 0.667-0.727 in chicken and bean sprouts, respectively. Therefore, screening for E. albertii-specific genes using EA-rtPCR followed by isolation with RX-DHL or RX-MAC is an efficient method for E. albertii detection in food.

Culture media and format alter cellular composition and barrier integrity of porcine colonoid-derived monolayers

Intestinal organoid technology has revolutionized our approach to in vitro cell culture due in part to their three-dimensional structures being more like the native tissue from which they were derived with respect to cellular composition and architecture. For this reason, organoids are becoming the new gold standard for undertaking intestinal epithelial cell research. Unfortunately, their otherwise advantageous three-dimensional geometry prevents easy access to the apical epithelium, which is a major limitation when studying interactions between dietary or microbial components and host tissues. To overcome this problem, we developed porcine colonoid-derived monolayers cultured on both permeable Transwell inserts and tissue culture treated polystyrene plates. We found that seeding density and culture format altered the expression of genes encoding markers of specific cell types (stem cells, colonocytes, goblets, and enteroendocrine cells), and barrier maturation (tight junctions). Additionally, we found that changes to the formulation of the culture medium altered the cellular composition of colonoids and of monolayers derived from them, resulting in cultures with an increasingly differentiated phenotype that was similar to that of their tissue of origin.

Evaluation of CHROMagar Candida Plus for the detection of C. auris with a panel of 206 fungal isolates and 83 colonization screening skin-swabs

CHROMagar Candida Plus is a new formulation of chromogenic media designed for the detection and differentiation of major clinical Candida species, including Candida auris. The objective of this study is to evaluate CHROMagar Candida Plus when used according to manufacturer's instructions with a panel of 206 fungal isolates and 83 skin-swab specimens originally collected for C. auris colonization screening. Of the 68 C. auris isolates tested, 66/68 displayed the expected light-blue colony morphology and blue halo within 48 h. None of the remaining 138 non-auris isolates appeared similar to C. auris. CHROMagarCandida Plus was, therefore, inclusive to 97% of 68 C. auris isolates tested and supported visual exclusion of 100% of the 138 non-C. auris isolates tested. For the 83 colonization screening specimens, direct plating onto CHROMagarCandida Plus was 60% sensitive and 100% specific when compared to the enrichment broth gold-standard reference method. In sum, these findings demonstrate the utility of this media when working with isolates but also notable limitations when working with primary skin-swabs specimens when competing yeast species are present.IMPORTANCECandida auris is an emerging fungal pathogen of public health concern. As it continues to spread, it is important to publish evaluations of new diagnostic tools. In this study, we share our experience with a new chromogenic media which can help distinguish C. auris from related species.

Development of a fast and simple method for the isolation of superparamagnetic iron oxide nanoparticles protein corona from protein-rich matrices

The adsorption of proteins onto the surface of nanoparticle (NP) leads to the formation of the so-called "protein corona" as consisting both loosely and tightly bound proteins. It is well established that the biological identity of NPs that may be acquired after exposure to a biological matrix is mostly provided by the components of the hard corona as the pristine surface is generally less accessible for binding. For that reason, the isolation and the characterisation of the NP-corona complexes and identification of the associated biomolecules can help in understanding its biological behaviour. Established methods for the isolation of the NP-HC complexes are time-demanding and can lead to different results based on the isolation method applied. Herein, we have developed a fast and simple method using ferromagnetic beads isolated from commercial MACS column and used for the isolation of superparamagnetic NP following exposure to different types of biological milieu. We first demonstrated the ability to easily isolate superparamagnetic iron oxide NPs (IONPs) from different concentrations of human blood plasma, and also tested the method on the corona isolation using more complex biological matrices, such as culture medium containing pulmonary mucus where the ordinary corona methods cannot be applied. Our developed method showed less than 20% difference in plasma corona composition when compared with centrifugation. It also showed effective isolation of NP-HC complexes from mucus-containing culture media upon comparing with centrifugation and MACS columns, which failed to wash out the unbound proteins. Our study was supported with a full characterisation profile including dynamic light scattering, nanoparticle tracking analysis, analytical disk centrifuge, and zeta potentials. The biomolecules/ proteins composing the HC were separated by vertical gel electrophoresis and subsequently analysed by liquid chromatography-tandem mass spectrometry. In addition to our achievements in comparing different isolation methods to separate IONPs with corona from human plasma, this is the first study that provides a complete characterisation profile of particle protein corona after exposure in vitro to pulmonary mucus-containing culture media.

Impact of sporulation temperature on germination of Bacillus subtilis spores under optimal and adverse environmental conditions

Bacillus subtilis spores are important food spoilage agents and are occasionally involved in food poisoning. In foods that are not processed with intense heat, such bacterial spores are controlled by a combination of different hurdles, such as refrigeration, acidification, and low water activity (aw), which inhibit or delay germination and/or growth. Sporulation temperature has long been regarded as a relevant factor for the assessment of germination in chemically defined media, but little is known about its impact on food preservation environments. In this study, we compared germination dynamics of B. subtilis spores produced at optimal temperature (37 °C) with others incubated at suboptimal (20 °C) and supraoptimal (43 °C) temperatures in a variety of nutrients (rich-growth medium, L-alanine, L-valine, and AGFK) under optimal conditions as well as under food-related stresses (low aw, pH, and temperature). Spores produced at 20 °C had a lower germination rate and efficiency than those incubated at 37 °C in all the nutrients, while those sporulated at 43 °C displayed a higher germination rate and/or efficiency in response to rich-growth medium and mostly to L-alanine and AGFK under optimal environmental conditions. However, differences in germination induced by changes in sporulation temperature decreased when spores were activated by heat, mainly due to the greater benefit of heat for spores produced at 20 °C and 37 °C than at 43 °C, especially in AGFK. Non-heat-activated spores produced at 43 °C still displayed superior germination fitness under certain stresses that had considerably impaired the germination of the other two populations, such as reduced temperature and aw. Moreover, they presented lower temperature and pH boundaries for the inhibition of germination in rich-growth medium, while requiring a higher NaCl concentration threshold compared to spores obtained at optimal and suboptimal temperature. Sporulation temperature is therefore a relevant source of variability in spore germination that should be taken into account for the accurate prediction of spore behaviour under variable food preservation conditions with the aim of improving food safety and stability.

Life cycle assessment and technoeconomic analysis of biofuels produced from polyculture microalgae cultivated in greywater

This study evaluated the environmental and economic impacts of substituting synthetic media with greywater for cultivating microalgae in the biofuel production process. Life cycle assessment (LCA) and technoeconomic assessment (TEA) were employed to compare the impacts of two scenarios - one containing bold's basal (BB) media and another containing greywater as growth mediums for microalgae cultivation. Scenarios 1 and 2 mitigated 1.74 and 2.14 kg CO2 per kg of biofuel production, respectively. Substituting BB media with greywater resulted in a 16.3% reduction in energy requirements, leading to a 79.3% increase in net energy recovered. LCA findings demonstrate a reduction in all seven environmental categories. TEA reveals that, despite a 21.7% higher capital investment, scenario 2 proves more economically viable due to a 39.8% lower operating cost and additional revenue from wastewater treatment and carbon credits. The minimum selling price of biofuel dropped from Rs 73.5/kg to Rs 36.5/kg, highlighting the economic and environmental advantages of substituting BB media with greywater in microalgal biofuel production.

Production of nisin from Lactococcus lactis in acid-whey with nutrient supplementation

The production of Nisin, an FDA-approved food preservative, was attempted by Lactococcus lactis subsp. lactis ATCC® 11454 using the underutilized milk industry effluent, acid-whey, as a substrate. Nisin production was further improved by studying the effect of supplementation of nutrients and non-nutritional parameters. The addition of yeast extract (6% w/v) as nitrogen source and sucrose (4% w/v) as carbon source were found to be suitable nutrients for the maximum nisin production. The changes in the medium pH due to lactic acid accumulation during batch fermentation and its influence on the production of nisin were analyzed in the optimized whey medium (OWM). The production characteristics in OWM were further compared with the nisin production in MRS media. The influence of nisin as an inducer for its own production was also studied and found that the addition of nisin at 0.22 mg/ml promote the nisin production. The analysis of consumption of various metal ions present in the OWM during the nisin production was also analyzed, and found that the copper ions are the most consumed ion. The highest nisin yield of 2.6 × 105 AU/mL was obtained with OWM.

Optimization of bacterial cellulose production by Komagataeibacter sucrofermentans in synthetic media and agrifood side streams supplemented with organic acids and vitamins

The effect of thiamine (TA), ascorbic acid (AA), citric acid, and gallic acid (GA) on bacterial cellulose (BC) production by Komagataeibacter sucrofermentans, in synthetic (Hestrin and Schramm, HS) and natural substrates (industrial raisins finishing side stream extract, FSSE; orange juice, OJ; green tea extract, GTE), was investigated. The Response Surface Methodology was found reliable for BC yield prediction and optimization. Higher yields were achieved in the FSSE substrates, especially those supplemented with AA, TA, and GA (up to 19.4 g BC/L). The yield in the non-fortified substrates was 1.1-5.4 and 11.6-15.7 g/L, in HS and FSSE, respectively. The best yield in the natural non-fortified substrate FSSE-OJ-GTE (50-20-30 %), was 5.9 g/L. The porosity, crystallinity, and antioxidant properties of the produced BC films were affected by both the substrate and the drying method (freeze- or oven-drying). The natural substrates and the process wastewaters can be further exploited towards added value and sustainability. Take Home Message Sentence: Raisin and citrus side-streams can be efficiently combined for bacterial cellulose production, enhanced by other vitamin- and phenolic-rich substrates such as green tea.

A Multicenter Study on the Utility of Selective Enrichment Broth for Detection of Group B Streptococcus in Pregnant Women in Japan

Universal screening for Streptococcus agalactiae, Group B Streptococcus (GBS), in pregnant women is important for the prevention of severe infectious diseases in neonates. The subculture method using selective enrichment broth significantly improves GBS detection rates in the United States; however, this method is not widely utilized in Japan mainly because of the lack of large-scale validation. Therefore, we aimed to validate the utility of the subculture method in collaboration with multiple facilities. A total of 1957 vaginal-rectal swab specimens were obtained from pregnant women at 35-37 gestational weeks from March 1, 2020, to August 30, 2020, at Fukushima Medical University Hospital, Aiiku Hospital, Kitano Hospital, and the University of the Ryukyus Hospital. Conventional direct agar plating, subculture using selective enrichment broth, and direct latex agglutination (LA) testing with incubated broth were performed for GBS detection, and discrepant results were confirmed using real-time PCR. The GBS detection rates for direct agar plating, subculture, and direct LA testing were 18.2% (357/1957), 21.6% (423/1957), and 22.3% (437/1957), respectively. The use of selective enrichment broth showed promise for GBS detection with high sensitivity and is therefore recommended for GBS screening to prevent GBS-related infectious diseases in neonates in Japan.

Integrated Omics Approach: Revealing the Mechanism of Auxenochlorella pyrenoidosa Protein Extract Replacing Fetal Bovine Serum for Fish Muscle Cell Culture

The process of producing cell-cultured meat involves utilizing a significant amount of culture medium, including fetal bovine serum (FBS), which represents a considerable portion of production expense while also raising environmental and safety concerns. This study demonstrated that supplementation with Auxenochlorella pyrenoidosa protein extract (APE) under low-serum conditions substantially increased Carassius auratus muscle (CAM) cell proliferation and heightened the expression of Myf5 compared to the absence of APE. An integrated intracellular metabolomics and proteomics analysis revealed a total of 13 and 67 differentially expressed metabolites and proteins, respectively, after supplementation with APE in the medium containing 5%FBS, modulating specific metabolism and signaling pathways, which explained the application of APE for passage cell culture under low-serum conditions. Further analysis revealed that the bioactive factors in the APE were protein components. Moreover, CAM cells cultured in reconstructed serum-free media containing APE, l-ascorbic acid, insulin, transferrin, selenium, and ethanolamine exhibited significantly accelerated growth in a scale-up culture. These findings suggest a promising alternative to FBS for fish muscle cell culture that can help reduce production costs and environmental impact in the production of cultured meat.

Characterization of oviduct epithelial spheroids for the study of embryo-maternal communication in cattle

Most in vitro models of oviduct epithelial cells (OEC) used thus far to gain insights into embryo-maternal communication induce cell dedifferentiation or are technically challenging. Moreover, although the presence of developing embryos has been shown to alter gene expression in OEC, the effect of embryos on OEC physiology remains largely unknown. Here, we propose a model based on bovine oviduct epithelial spheroids (OES) with specific shape and diameter (100-200 μm) criteria. The aims of this study were to i) determine the appropriate culture conditions of bovine OES cultured in suspension by evaluating their morphology, total cell number, viability, and activity of ciliated cells; ii) monitor gene expression in OES at the time of their formation (day 0) and over the 10 days of culture; and iii) test whether the vicinity of developing embryos affects OES quality criteria. On day 10, the proportions of vesicle-shaped OES (V-OES) were higher in M199/500 (500 μl of HEPES-buffered TCM-199) and synthetic oviduct fluid (SOF)/25 (25-μL droplet of SOF medium under mineral oil) than in M199/25 (25-μL droplet of M199 under mineral oil). The proportion of viable cells in V-OES was not affected by culture conditions and remained high (>80%) through day 10. The total number of cells per V-OES decreased over time except in SOF/25, while the proportions of ciliated cells increased over time in M199/500 but decreased in M199/25 and SOF/25. The movement amplitude of OES in suspension decreased over time under all culture conditions. Moreover, the gene expression of ANXA1, ESR1, HSPA8, and HSPA1A in OES remained stable during culture, while that of PGR and OVGP1 decreased from day 0 to day 10. Last, the co-culture of developing embryos with OES in SOF/25 increased the rates of blastocysts on days 7 and 8 compared to embryos cultured alone, and increased the proportion of V-OES compared to OES cultured alone. In conclusion, M199/500 and SOF/25 provided the optimal conditions for the long-time culture of OES. The supporting effect of OES on embryo development and of developing embryos on OES morphology was evidenced for the first time. Altogether, these results point OES as an easy-to-use, standardizable, and physiological model to study embryo-maternal interactions in cattle.

Roles of pH and phosphate in rare earth element biosorption with living acidophilic microalgae

The increasing demand for rare earth elements (REEs) has spurred interest in the development of recovery methods from aqueous waste streams. Acidophilic microalgae have gained attention for REE biosorption as they can withstand high concentrations of transition metals and do not require added organic carbon to grow, potentially allowing simultaneous sorption and self-replication of the sorbent. Here, we assessed the potential of Galdieria sulphuraria for REE biosorption under acidic, nutrient-replete conditions from solutions containing ≤ 15 ppm REEs. Sorption at pH 1.5-2.5 (the growth optimum of G. sulphuraria) was poor but improved up to 24-fold at pH 5.0 in phosphate-free conditions. Metabolic activity had a negative impact on REE sorption, additionally challenging the feasibility of REE biosorption under ideal growth conditions for acidophiles. We further examined the possibility of REE biosorption in the presence of phosphate for biomass growth at elevated pH (pH ≥ 2.5) by assessing aqueous La concentrations in various culture media. Three days after adding La into the media, dissolved La concentrations were up to three orders of magnitude higher than solubility predictions due to supersaturation, though LaPO4 precipitation occurred under all conditions when seed was added. We concluded that biosorption should occur separately from biomass growth to avoid REE phosphate precipitation. Furthermore, we demonstrated the importance of proper control experiments in biosorption studies to assess potential interactions between REEs and matrix ions such as phosphates. KEY POINTS: • REE biosorption with G. sulphuraria increases significantly when raising pH to 5 • Phosphate for biosorbent growth has to be supplied separately from biosorption • Biosorption studies have to assess potential matrix effects on REE behavior.

Identification and pathogenicity of Fusarium species associated with wilting and crown rot in almond (Prunus dulcis)

Severe Fusarium wilt and crown root symptoms were observed in almond orchards in Portugal. The present study elucidates the etiology of the disease through molecular, phenotypic, and pathogenic characterization. Three Fusarium isolates from Portugal were tested and 12 Fusarium isolates from almond from Spain were included for comparative purposes. Their identity was inferred by phylogenetic analysis combining tef1 and rpb2 sequences. The Portuguese isolates were identified as Fusarium oxysporum sensu stricto (s.s.), and the Spanish isolates as Fusarium nirenbergiae, F. oxysporum (s.s.), Fusarium proliferatum, Fusarium redolens (s.s.), Fusarium sambucinum (s.s.), and Fusarium sp. Fungal colonies and conidia were characterized on potato dextrose agar (PDA) and on Synthetischer Nährstoffarmer agar, respectively. The colonies had a variable morphology and their color ranged from white to pale violet. Typical Fusarium micro- and macroconidia were characterized. Temperature effect on mycelial growth was evaluated on PDA from 5 to 35 °C, with optimal growth temperature ranging between 16.8 and 26.4 °C. The pathogenicity of F. oxysporum was demonstrated by inoculating almond plants ('Lauranne') grafted on GF-677 or Rootpac 20 rootstocks. A significant reduction in plant growth, wilting, and xylem discoloration was observed, with Rootpac 20 being more susceptible than GF-677. Infections were also reproduced using naturally infested soils. Almond plants ('Lauranne') were inoculated with isolates of all Fusarium species, with F. redolens from Spain and F. oxysporum from Portugal being the most aggressive.

Object-centered family interactions for young autistic children: a diary study

Autistic Children often struggle with social interaction and communication, studies have found that many of them prefer to interact with objects than people. However, there is a lack of research exploring the specific characteristics and factors involved in interactions within families with autistic children where objects are the center of the interaction. This paper describes the process and findings of a diary study exploring how young autistic children interact with their families through objects in natural scenarios. A one-week diary study was conducted with six families with young autistic children. Diary videos were recorded onsite and coded later according to a social interaction behavior scheme with corresponding diary entries. Qualitative data analysis was conducted to reveal possible patterns. Results revealed ongoing difficulties in establishing and maintaining family interaction and identified influential factors of object-centered family interaction. The most prevalent pattern observed was parents taking the lead in interactions, followed by the child's confirmation response. Remarkably, daily necessities emerged as potential physical mediums for enhancing family interactions, opening avenues for exploring tangible designs in human-computer interaction. These findings offer valuable implications for future research and the development of innovative designs that promote enriching interactions for autistic children and their families.

Exploring Culture Media Diversity to Produce Fungal Secondary Metabolites and Cyborg Cells

Fungi are microorganisms of significant biotechnological importance due to their ability to provide food and produce several value-added secondary metabolites and enzymes. Its products move billions of dollars in the pharmaceutical, cosmetics, and additives sectors. These microorganisms also play a notable role in bionanotechnology, leading to the production of hybrid biological-inorganic materials (such as cyborg cells) and the use of their enzyme complex in the biosynthesis of nanoparticles. In this sense, optimizing the fungal growth process is necessary, with selecting the cultivation medium as one of the essential factors for the microorganism to reach its maximum metabolic expression. The culture medium's composition can also impact the nanomaterial's stability and prevent the incorporation of nanoparticles into fungal cells. Therefore, our main objectives are the following: (1) compile and discuss the most commonly employed culture media for the production of fungal secondary metabolites and the formation of cyborg cells, accompanied by preparation methods; (2) provide a six-step guide to investigating the fungal metabolomic profile and (3) discuss the main procedures of microbial cultivation to produce fungal cyborg cells.

Measuring Bacterial Colonization on Arabidopsis thaliana Roots in Hydroponic Condition

Measuring bacterial colonization on Arabidopsis thaliana root is one of the most frequent experiments in plant-microbe interaction studies. A standardized method for measuring bacterial colonization in the rhizosphere is necessary to improve reproducibility. We first cultured sterile A.thaliana in hydroponic conditions and then inoculated the bacterial cells in the rhizosphere at a final concentration of OD600 of 0.01. At 2 days post-inoculation, the root tissue was harvested and washed three times in sterile water to remove the uncolonized bacterial cells. The roots were then weighed, and the bacterial cells colonized on the root were collected by vortex. The cell suspension was diluted in a gradient with a phosphate-buffered saline (PBS) buffer, followed by plating onto a Luria-Bertani (LB) agar medium. The plates were incubated at 37 °C for 10 h, and then, the single colonies on LB plates were counted and normalized to indicate the bacterial cells colonized on roots. This method is used to detect bacterial colonization in the rhizosphere in mono-interaction conditions, with good reproducibility.

Do IVF culture conditions have an impact on neonatal outcomes? A systematic review and meta-analysis

PURPOSE

Are embryo culture conditions, including type of incubator, oxygen tension, and culture media, associated with obstetric or neonatal complications following in vitro fertilization (IVF)?

METHODS

A systematic search of MEDLINE, EMBASE, and Cochrane Library was performed from January 01, 2008, until October 31, 2021. The studies reporting quantitative data on at least one of the primary outcomes (birthweight and preterm birth) for the exposure group and the control group were included. For oxygen tension, independent meta-analysis was performed using Review Manager, comparing hypoxia/normoxia. For culture media, a network meta-analysis was carried out using R software, allowing the inclusion of articles comparing two or more culture media.

RESULTS

After reviewing 182 records, 39 full-text articles were assessed for eligibility. A total of 28 studies were kept for review. Meta-analysis about the impact of incubator type on perinatal outcomes could not be carried out because of a limited number of studies. For oxygen tension, three studies were included. The pairwise meta-analysis comparing hypoxia/normoxia did not show any statistical difference for birthweight and gestational age at birth. For culture media, 18 studies were included. The network meta-analysis failed to reveal any significant impact of different culture media on birthweight or preterm birth.

CONCLUSION

No difference was observed for neonatal outcomes according to the embryo culture conditions evaluated in this review. Further research is needed about the safety of IVF culture conditions as far as future children's health is concerned.

Validation of rapid detection methods for Salmonella enterica in green chile

The objective of this study is to validate the US Food and Drug Administration (FDA) rea-time polymerase chain reaction (qPCR) assay, the Neogen Amplified Nucleic Single Temperature Reaction (ANSR) assay, and the Vitek ImmunoDiagnostic Assay System (VIDAS) SLM procedure against the FDA cultural procedure for Salmonella detection in green chile pepper. Green chile was artificially contaminated with Salmonella according to the FDA guidelines (FDA. Guidelines for the Validation of Microbiological Methods for the FDA Foods Program, 3rd Edition. 2019. www.fda.gov/media/83812/download?attachment (17 March 2024, date last accessed)) at a fractional recovery level (where 50%-25% tests positive and at a level +1 log greater for each organism tested). Enriched samples were tested directly by the ANSR Salmonella test and by qPCR, and were subcultured into Rappaport-Vassiliadis and tetrathionate brilliant green broth for cultural detection and qPCR. For the VIDAS-SLM assay, the selective enrichments were further cultured in M broth before testing. Presumptive salmonellae were confirmed with biochemical tests, serology, and qPCR. All three rapid assays were compared favorably with the FDA-BAM (Bacteriological Analytical Manual) method. No significant differences at P < .05 were found between the procedures using McNemar's χ2 test. The three procedures were found to be rapid and reliable alternatives to cultural detection of Salmonella enterica in green chile.

Impact of culture media on primary human corneal endothelial cells derived from old donors

Corneal endothelial dysfunction is a major indication for corneal transplantation. However, a global shortage of donor corneal tissues and risks associated with corneal surgeries have prompted exploration of alternative options, including tissue-engineered grafts or cell injection therapy. Nonetheless, these approaches require a controlled culture of primary human corneal endothelial cells (HCEnCs). Although HCEnCs established from young donors are generally more proliferative and maintain a better phenotype, corneas from old donors are more frequently accessible from eye banks due to a lower corneal endothelial cell count than the necessary threshold required for transplantation. In this study, we investigated various culture media to evaluate which one is the most appropriate for stimulating the proliferation while maintaining cell morphology and function of HCEnCs derived from old donors (age >65 years). All experiments were performed on paired research-grade donor corneas, divided for the conditions under investigation in order to minimize the inter-donor variability. Cell morphology as well as expression of specific markers were assessed at both mRNA (CD166, SLC4A11, ATP1A1, COL8A1, α-SMA, CD44, COL1A1, CDKN2A, LAP2A and LAP2B) and protein (ZO-1, α-SMA, Ki67 and LAP2) levels. Results obtained showed how the Dual Media formulation maintained the hexagonal phenotype more efficiently than Single Medium, but cell size gradually increased with passages. In contrast, the Single Medium provided a higher proliferation rate and a prolonged in vitro expansion but acquired an elongated morphology. To summarize, Single medium and Dual media preserve morphology and functional phenotype of HCEnCs from old donor corneas at low passages while maintenance of the same cell features at high passages remains an active area of research. The new insights revealed within this work become particularly relevant considering that the elderly population a) is the main target of corneal endothelial therapy, b) represents the majority of corneal donors. Therefore, the proper expansion of HCEnCs from old donors is essential to develop novel personalised therapeutic strategies and reduce requirement of human corneal tissues globally.

The unbearable ignorance of the composition of IVF culture media

Culture media play an essential role in the success of IVF. Their composition has undergone major modifications over the 45 years since the birth of Louise Brown. Most IVF programmes now rely on commercially produced media, which they buy in small vials, guaranteed to be sterile and non-embryotoxic. Unfortunately, information about the components of the culture media and their concentrations is no longer available. Arguing that culture media recipes are proprietary, relevant commercial interests have stopped labelling their products with this vital information. Given the critical role that is played by culture media in the success of IVF, as well as the subsequent health of the children who are born after IVF, this information should not remain a 'company secret'. Clinicians and scientists working in IVF must insist that the labelling of culture media includes all of the constituents and their concentrations. Only in this way can we monitor the influence of culture media on IVF outcomes, innovate and continue to advance the field of IVF.

Engineering Saccharomyces cerevisiae for fast vitamin-independent aerobic growth

Chemically defined media for cultivation of Saccharomyces cerevisiae strains are commonly supplemented with a mixture of multiple Class-B vitamins, whose omission leads to strongly reduced growth rates. Fast growth without vitamin supplementation is interesting for industrial applications, as it reduces costs and complexity of medium preparation and may decrease susceptibility to contamination by auxotrophic microbes. In this study, suboptimal growth rates of S. cerevisiae CEN.PK113-7D in the absence of pantothenic acid, para-aminobenzoic acid (pABA), pyridoxine, inositol and/or biotin were corrected by single or combined overexpression of ScFMS1, ScABZ1/ScABZ2, ScSNZ1/ScSNO1, ScINO1 and Cyberlindnera fabianii BIO1, respectively. Several strategies were explored to improve growth of S. cerevisiae CEN.PK113-7D in thiamine-free medium. Overexpression of ScTHI4 and/or ScTHI5 enabled thiamine-independent growth at 83% of the maximum specific growth rate of the reference strain in vitamin-supplemented medium. Combined overexpression of seven native S. cerevisiae genes and CfBIO1 enabled a maximum specific growth rate of 0.33 ± 0.01 h-1 in vitamin-free synthetic medium. This growth rate was only 17 % lower than that of a congenic reference strain in vitamin-supplemented medium. Physiological parameters of the engineered vitamin-independent strain in aerobic glucose-limited chemostat cultures (dilution rate 0.10 h-1) grown on vitamin-free synthetic medium were similar to those of similar cultures of the parental strain grown on vitamin-supplemented medium. Transcriptome analysis revealed only few differences in gene expression between these cultures, which primarily involved genes with roles in Class-B vitamin metabolism. These results pave the way for development of fast-growing vitamin-independent industrial strains of S. cerevisiae.

An alternative peptone preparation using Hermetia illucens (Black soldier fly) hydrolysis: process optimization and performance evaluation

Background

Hermetia illucens (HI), commonly known as the black soldier fly, has been recognized for its prowess in resource utilization and environmental protection because of its ability to transform organic waste into animal feed for livestock, poultry, and aquaculture. However, the potential of the black soldier fly's high protein content for more than cheap feedstock is still largely unexplored.

Methods

This study innovatively explores the potential of H. illucens larvae (HIL) protein as a peptone substitute for microbial culture media. Four commercial proteases (alkaline protease, trypsin, trypsase, and papain) were explored to hydrolyze the defatted HIL, and the experimental conditions were optimized via response surface methodology experimental design. The hydrolysate of the defatted HIL was subsequently vacuum freeze-dried and deployed as a growth medium for three bacterial strains (Staphylococcus aureus, Bacillus subtilis, and Escherichia coli) to determine the growth kinetics between the HIL peptone and commercial peptone.

Results

The optimal conditions were 1.70% w/w complex enzyme (alkaline protease: trypsin at 1:1 ratio) at pH 7.0 and 54 °C for a duration of 4 h. Under these conditions, the hydrolysis of defatted HIL yielded 19.25% ±0.49%. A growth kinetic analysis showed no significant difference in growth parameters (μmax, Xmax, and λ) between the HIL peptone and commercial peptone, demonstrating that the HIL hydrolysate could serve as an effective, low-cost alternative to commercial peptone. This study introduces an innovative approach to HIL protein resource utilization, broadening its application beyond its current use in animal feed.

Detection and Isolation of Campylobacter spp. from Raw Meat

This article presents a rapid yet robust protocol for isolating Campylobacter spp. from raw meats, specifically focusing on Campylobacter jejuni and Campylobacter coli. The protocol builds upon established methods, ensuring compatibility with the prevailing techniques employed by regulatory bodies such as the Food and Drug Administration (FDA) and the U.S. Department of Agriculture (USDA) in the USA, as well as the International Organization for Standardization (ISO) in Europe. Central to this protocol is collecting a rinsate, which is concentrated and resuspended in Bolton Broth media containing horse blood. This medium has been proven to facilitate the recovery of stressed Campylobacter cells and reduce the required enrichment duration by 50%. The enriched samples are then transferred onto nitrocellulose membranes on brucella plates. To improve the sensitivity and specificity of the method, 0.45 µm and 0.65 µm pore-size filter membranes were evaluated. Data revealed a 29-fold increase in cell recovery with the 0.65 µm pore-size filter compared to the 0.45 µm pore-size without impacting specificity. The highly motile characteristics of Campylobacter allow cells to actively move through the membrane filters towards the agar medium, which enables effective isolation of pure Campylobacter colonies. The protocol incorporates multiplex quantitative real-time polymerase chain reaction (mqPCR) assay to identify the isolates at the species level. This molecular technique offers a reliable and efficient means of species identification. Investigations conducted over the past twelve years involving retail meats have demonstrated the ability of this method to enhance recovery of Campylobacter from naturally contaminated meat samples compared to current reference methods. Furthermore, this protocol boasts reduced preparation and processing time. As a result, it presents a promising alternative for the efficient recovery of Campylobacter from meat. Moreover, this procedure can be seamlessly integrated with DNA-based methods, facilitating rapid screening of positive samples alongside comprehensive whole-genome sequencing analysis.

Functional features of the exopolysaccharide extracts produced by Lactiplantibacillus strains isolated from table olives

This study evaluates the functional characteristics of the exopolysaccharide (EPS) extracts produced by various strains of Lactiplantibacillus pentosus (LPG1, 119, 13B4, and Lp13) and Lactiplantibacillus plantarum (Lp15) isolated from table olives. None of the EPS crude extracts showed cytotoxicity when administered to THP-1 human macrophage cells at dosages ranging from 6.25 to 50 μg mL-1. Many exhibited anti-inflammatory properties (reduction of pro-inflammatory cytokines TNF-α and IL-6 production) and antioxidant activity (reduction of ROS%) when macrophages were stimulated with Escherichia coli lipopolysaccharide. Notably, the EPS extract produced by the L. pentosus LPG1 strain had the best results corroborated by western blot immune analysis for differential expression of COX-2, Nrf-2, and HO-1 proteins, with the most significant antioxidant and anti-inflammatory response observed at a dosage of 50 μg mL-1. Chemical analysis revealed that the EPS extract produced by this strain contains a heteropolymer composed of mannose (35.45%), glucose (32.99%), arabinose (17.93%), xylose (7.48%), galactose (4.03%), rhamnose (1.34%), and fucose (0.77%). Finally, we conducted response surface methodology to model the EPS extract production by L. pentosus LPG1 considering pH (3.48-8.52), temperature (16.59-33.41 °C) and salt concentration (0.03-8.77% NaCl) as independent variables. The model identified linear effects of salt and pH and quadratic effects of salt as significant terms. The maximum EPS extract production (566 mg L-1) in a synthetic culture medium (MRS) was achieved at pH 7.5, salt 7.0%, and a temperature of 20 °C. These findings suggest the potential for novel applications for the EPS produced by L. pentosus LPG1 as nutraceutical candidates for use in human diets.

New Antibiotic Binding Resin Bottles Collected from Children Enhances Rapid Microbial Identification

BACKGROUND

Bloodstream infections (BSI) represent a common cause of sepsis and mortality in children. Blood culture (BC) is the gold standard for diagnosis of BSI. The low sensitivity of BC in the pediatric population is usually due to the small volume of blood used for inoculation and to the antibiotics used before sampling. Here, we explore the ways to effectively reduce antibiotic activity to maximize the chances of pathogen recovery, and to enhance the growth of microorganisms in lower blood volume and bacterial counts.

METHODS

The recovery of common pathogens causing blood stream infections was analyzed after exposure to cefo-perazone/sulbactam, vancomycin, and caspofung by using resin-containing or not BacT/Alert PF Plus and BD FX400 peds plus pediatric bottles. The microbial growth in the resin-containing bottles was assessed using 0.5 colony-forming units (CFU) bacterial inoculum to mimic the bacteremia/fungemia condition. The usefulness of a diagnosis to confirm or exclude BSI was evaluated by lower than recommended blood culture sampling (102 CFU/mL, 0.3 mL).

RESULTS

Staphylococcus aureus (S. aureus), and Candida glabrata (C. glabrata) were recovered from 100% of two types of resin-containing bottles in the presence of a sufficient antibiotic dose, while Escherichia coli (E. coli) was not restored to 100% in BD FX400 peds plus pediatric bottles. The shorter TTD for S. aureus, C. glabrata, and E. coli were observed in antibiotic-containing BacT/Alert PF Plus bottles. Both the PF Plus and BD resin test bottles showed consistently good TTD performances to Gram-negative, Gram-positive, and yeast species in low inoculum levels, with the exception of S. aureus. The lower volume of blood inoculated into culture bottles hardly affected the growth of most bacteria, but optimized PF Plus resin-bottles accelerated the detection of infectious agents, especially S. aureus, Streptococcus pneumoniae, and C. glabrata.

CONCLUSIONS

It is possible to enhance recovery from antibiotic-containing pediatric bottles and shorten TTD for the identification of pathogens by using the BacT/Alert blood culture system combination with new resin-containing media.

A rapid and simple sterility test method based on solid culture medium containing blood

Current sterility test performed for most biological products takes 14 days. We evaluated solid medium, containing 5% blood for use in the membrane filtration (MF) and direct inoculation (DI) sterility test. Representative microorganisms prepared in a sample matrix at approximately 0.1, 1, 10 and 100 colony forming units were tested for growth by compendial MF sterility test using fluid thioglycolate medium and tryptic soy broth and also on the Schaedler blood agar (SBA). Sterility test performed on SBA was significantly more sensitive and faster in detecting various microorganisms than the compendial method, particularly for sample matrix containing 0.01% thimerosal (p < 0.05). SBA detected all microorganisms within 7 days. To implement solid medium in the DI sterility test, multiple BA plates were inoculated with the sample. All representative microorganisms were detected within 5 days. The sterility test using solid medium required 3 different incubation conditions, 30-35 °C aerobically and anaerobically to detect bacteria, and at 20-25 °C aerobically to detect mold and yeast. To eliminate aerobic incubation of solid medium at 20-25 °C, we evaluated representative species of mold and yeast for their growth at 30-35 °C and 20-25 °C in the sterility test performed on solid medium. Penicillium chrysogenum could not be detected at 30-35 °C consistently within 7 days. Sterility test performed on solid medium without any additional technology could be completed in 7 days, as compared to the 14 days required for the current compendial method.

Assessment of UV radiation effects on airborne mucormycetes and bacterial populations in a hospital environment

Infections, such as mucormycosis, often result from inhaling sporangiospore present in the environment. Surprisingly, the extent of airborne Mucormycetes sporangiospore concentrations remains inadequately explored. This study aimed to assess the influence of UV radiation on microbial populations and Mucormycetes spore levels within a hospital environment in northern Iran. A comprehensive dataset comprising 298 air samples collected from both indoor and outdoor settings was compiled. The culture was conducted using Blood Agar and Dichloran Rose Bengal Chloramphenicol (DRBC) culture media, with Chloramphenicol included for fungal agents and Blood Agar for bacterial. Before UV treatment, the average count of Mucormycetes ranged from 0 to 26.4 ± 25.28 CFU m-3, fungal agents from 2.24 ± 3.22 to 117.24 ± 27.6 CFU m-3, and bacterial agents from 29.03 ± 9.9 to 359.37 ± 68.50 CFU m-3. Following UV irradiation, the averages were as follows: Mucormycetes ranged from 0 to 7.85 ± 6.8 CFU m-3, fungal agents from 16.58 ± 4.79 to 154.98 ± 28.35 CFU m-3, and bacterial agents from 0.38 ± 0.65 to 43.92 ± 6.50 CFU m-3. This study, notably marks the pioneering use of UV light to mitigate Mucormycetes spore counts and bacterial agents in northeastern Iran, contributing to the advancement of environmental health and safety practices in hospital settings.

Comparison of CHROMagar Orientation Medium with Traditional Methods in Urinary Tract Infection Cultures

BACKGROUND

Urinary tract infections (UTIs) are the most common infections in adults, and urine culture is the parameter that uses the most time and cost in microbiology laboratories. For this reason, the selection of fast and cost-effective methods in the evaluation of urine samples is one of the priority issues of microbiology laboratories. The aim of this study was to investigate the compatibility and cost-effectiveness of routinely used Blood Agar (BA), Eosin Methylene Blue (EMB) medium, and CHROMagar Orientation Medium (CO Medium) in the identification of microorganisms in urine samples.

METHODS

Consecutive urine samples (n: 700) sent to our laboratory were simultaneously inoculated onto BA/EMB media and CO medium. Urine samples were evaluated after 18 - 24 hours of incubation at 37℃ and the compatibility of the two methods was compared. The use of 104 Gram stains, 198 biochemical tests, and 9 identification kits was required with BA/EMB agar.

RESULTS

When 104 colonies with single growth were evaluated, presumptive identification with CO medium was found to be 100% compatible with the VITEK 2 system. The most isolated 62 Escherichia coli (E. coli) colonies gave dark pink-red color and were found to be fully compatible with the VITEK 2 system. Compatibility of BA and EMB medium evaluations with VITEK 2 system; E. coli (n: 62), KES group (n: 26), Pseudomonas spp. (n: 6) and Proteus spp. For (n: 2), it was determined as 69.3%, 57.69%, 100%, and 100%, respectively. According to the results of our study, when BA/EMB and CO Medium methods were compared, 182 Euro (€) savings were achieved in 700 urine cultures with CO Medium. It was estimated that the amount of savings could be 15,600 € per year.

CONCLUSIONS

CHROMagar Orientation Medium method can be used routinely with its advantages such as being cost-effective, reducing the workload, and not requiring additional operations. CHROMagar Orientation Medium can also be considered as an easily accessible method and opportunity that does not require infrastructure and trained personnel, especially for laboratories with low test capacity and having problems with the supply of com-mercial kits and automated systems.

Comparing minimum inhibitory concentrations of amikacin for pulmonary Mycobacterium avium complex disease: An analysis of culture media differences

Mycobacterium avium complex (MAC) is considered a paramount microbe, especially in East Asia, including Japan. The commonly used commercial Minimum Inhibitory Concentrations (MIC) assay using Middlebrook 7H9 (7H9) medium deviates from the latest Clinical and Laboratory Standards Institute (CLSI) guidelines. Alternatively, measurement with cation-adjusted Mueller-Hinton broth (CAMHB) that conforms to CLSI standards is not yet widely available. Following the approval and commercialization of amikacin liposome inhalation suspension (ALIS) in 2021, a more precise evaluation of amikacin (AMK) susceptibility in MAC is necessary for treatment decisions. In the present study, 33 sputum samples were extracted from 27 patients, and MICs of AMK were compared between the frequently used 7H9 and the recommended CAMHB of the isolated MAC strains. The history of exposure to aminoglycosides for each sample was also added as clinical information. The findings indicated that there was only an 18% concordance rate in MIC between the two media, with 19 samples (58%) indicating lower MICs in 7H9 relative to CAMHB. The 17 samples had a history of exposure to aminoglycosides for periods ranging from 1.5 to 28 months. Specifically, 10 samples were exposed to amikacin by inhalation and intravenous injection, and the remaining seven samples had a history of ALIS inhalation. Samples with a prior utilization of aminoglycosides were significantly predisposed to developing resistance to ALIS compared to those without such a history (P = 0.046). Physicians are encouraged to scrutinize the findings of susceptibility testing utilizing CLSI-endorsed MIC assay using CAMHB medium to ascertain the optimal therapeutic approach.

Effect of antibacterial photodynamic therapy with chitosan nanoparticles on Aggregatibacter actinomycetemcomitans

BACKGROUND

This study aimed to assess the effect of antibacterial photodynamic therapy (aPDT) with chitosan nanoparticles on Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) in the culture medium.

MATERIALS AND METHODS

In this in vitro, experimental study, chitosan nanoparticles (CHNPs) containing indocyanine green (ICG) were first synthesized and characterized. A. actinomycetemcomitans was cultured on trypticase soy agar. The culture media containing A. actinomycetemcomitans were randomly subjected to the following six decontamination protocols: negative control subjected to sterile phosphate buffered saline (PBS) for 5 min, positive control exposed to 0.2 % chlorhexidine (CHX) for 5 min, exposure to 0.25 mg/mL ICG in the dark at 37 °C for 5 min, aPDT with 0.25 mg/mL ICG and diode laser (808 nm, 250 mW, 14.94 J/cm2, 30 s, 1 mm distance, 8 mm tip diameter), exposure to CHNPs containing 0.25 mg/mL ICG in the dark at 37 °C for 5 min, and aPDT with CHNPs containing 0.25 mg/mL ICG and diode laser. The number of colonies was counted, and analyzed by one-way ANOVA and Tamhane test (alpha=0.050).

RESULTS

Antimicrobial PDT with CHNPs, and CHX groups comparably showed the highest decontamination efficacy (P = 0.000).

CONCLUSION

The results showed optimal efficacy of aPDT with CHNPs containing 0.25 mg/mL ICG and 808 nm diode laser for reduction of A. actinomycetemcomitans colony count. Thus, aPDT appears to be as effective as CHX, but with fewer adverse effects.

Boosting algicidal efficiency of Alteromonas sp. FDHY-CJ against Skeletonema costatum through fermentation optimization

Algicidal bacteria exhibit promising potential against harmful algal blooms (HABs); however, their application has been limited due to their limited algicidal activity. This study demonstrates the enhanced algicidal activity of Alteromonas sp. FDHY-CJ bacteria against harmful Skeletonema costatum using a 5 L fermenter. Utilizing this refined framework increased the OD600 value and algal cell mortality by 6.50 and 2.88 times, respectively, compared to non-optimized culture cultivated in a flask using marine broth 2216E medium. The mechanism of action involves significant inhibition of algal photosynthetic efficiency with concurrent degradation of photosynthetic pigments. Relative to the non-optimized group, the optimized bacterial treatment led to a significant increase in H2O2 and MDA (malondialdehyde) by 19.54 and 4.22-fold, respectively, and resulted in membrane damage. The culture optimization procedure yielded effectual algicidal substances capable of considerably reducing the severity of S. costatum HABs through cell membrane disruption.

Concerning the presumptive identification of Candida kefyr on Uriselect™4 agar

OBJECTIVE

Non-albicans Candida species, such as Candida kefyr, are emerging pathogens. Chromogenic media are highly useful for the diagnosis of urinary tract infections (UTIs). The aim was to describe the behavior of this specie on a non-specific chromogenic medium.

METHODS

A retrospective study of cases of candiduria detected in the Microbiology laboratory of the Virgen de las Nieves Hospital in Granada (Spain) between 2016 and 2021 (N=2,130). Urine samples were quantitatively seeded on non-selective UriSelect™4 chromogenic agar.

RESULTS

Between 2016 and 2021, C. kefyr was the seventh most frequent Candida species responsible for candiduria in our setting (n=15). The macroscopic appearance of C. kefyr colonies, punctiform and bluish, allowed the direct identification of these microorganisms.

CONCLUSIONS

This study provides the first description of the specific behavior of C. kefyr on UriSelect™4 agar, which differentiates it from other Candida species based on its enzymatic characteristics.

Growth kinetics of Lactococcus lactis and Lactobacillus casei in liquid culture medium containing as prebiotics inulin or fructose

BACKGROUND

Predictive microbiology is a tool that allows us to evaluate the behavior of the concentration of biomass and estimated cells under extrinsic conditions, providing scientific and industrial benefits. In the present study, the growth of L. lactis and L. casei combined with inulin and fructose was modeled using the Gompertz sigmoidal growth functions and plotted using data obtained from batch culture in relation to biomass and cell concentration expressed as estimates in ln N (OD600nm and cells mL-1 ) as a function of time.

RESULTS

The results of the kinetic modeling indicated that (T1) A1B1 = L. lactis + fructose and (T4) A2B2 = L. casei + inulin presented the best function coefficients and best fits in most cases compared to the rest. The specific growth rate of the maximum acceleration was from 0.364 to 0.473 h-1 and 0.100 to 0.129 h-1 , the concentration of bacterial cells (A) was from 0.556 to 0.713 and 0.425 to 0.548 respectively and the time where (μ) occurred with a greater magnitude (L) fluctuated between 0.854 and 0.802 and when this time in (L) is very fast, it presents values of ≤0.072 to ≤0.092. Its coefficient of determination and/or multiple regression (R2 ) obtained in the two adjustments was 0.97.

CONCLUSION

It was possible to predict the influence of the carbon source on the behavior of maximum growth rates, higher consumption due to nutrient affinity and shorter growth time. © 2023 Society of Chemical Industry.

Metabolic stressful environment drives epigenetic modifications in oviduct epithelial cells

The oviduct provides a suitable microenvironment from the gametes' final maturation until initial embryo development. Dynamic functional changes are observed in the oviduct cells, mainly controlled by steroid hormones and well-orchestrated during the estrous cycle. However, based on the roles played by the oviduct, additional layers of complexity might be present in its regulatory process. There is a cellular process that includes metabolic adaptation that can guide molecular modifications. This process is known as metaboloepigenetics. Therefore, we aimed to better understand how this crosstalk occurs in oviductal epithelial cells (OEC). Due to limited in situ access to the oviduct, we used the primary in vitro cell culture as a culture model and glucose as a metabolic disturbed factor. For that, cells derived from the oviductal epithelial layer were collected from cows at either follicular or luteal stages (n = 4 animals per group). They were cultured on a monolayer culture system under normoglycemic (2.7 mM glucose) or hyperglycemic conditions (27 mM glucose). On day five of culture, attached cells were submitted to analysis of mitochondrial metabolism (mitochondrial membrane potential - MMP) and epigenetics markers (5- methylcytosine - 5 mC and histone 3 lysine 9 acetylation - H3K9ac). Moreover, the culture media were submitted to the metabolites analysis profile by Raman spectrometry. Data were analyzed considering the effect of glucose level (normoglycemic vs. hyperglycemic), stages when OEC were harvested (follicular vs. luteal), and their interaction (glucose level * cycle stage) by two-way ANOVA. As a result, the high glucose level decreased the H3K9ac and MMP levels but did not affect the 5 mC. Regardless of the metabolic profile of the culture media, the glucose level was the only factor that changed the Raman shifts abundance. Although this present study evaluated oviductal epithelial cells after being submitted to an in vitro monolayer culture system, which is known to lead to cell dedifferentiation, yet, these results provide evidence of a relationship between epigenetic reprogramming and energy metabolism under these cell culture conditions. In conclusion, the levels of metabolites in culture media may be crucial for cellular function and differentiation, meaning that it should be considered in studies culturing oviductal cells.

Divergent effects of the antiretroviral drugs, dolutegravir, tenofovir alafenamide, and tenofovir disoproxil fumarate, on human adipocyte function

Combined antiretroviral therapy (cART) has been associated with increased body weight accompanied by metabolic alterations in people living with human immunodeficiency virus (PLWH). To gain insight into the combined effects of cART components on adipocyte dysfunction, we assessed whether and how treatment of human adipocytes with dolutegravir (DTG) and the nucleotide-analog reverse-transcriptase inhibitors (NRTIs), tenofovir alafenamide (TAF) and tenofovir disoproxil fumarate (TDF), alone and in combination, altered biological processes related to adipose tissue dysfunction. DTG, TAF, and TDF were applied to human Simpson-Golabi-Behmel syndrome (SGBS) adipose cells during differentiation (day 10) and ensuing differentiation (day 14). Expression of selected marker genes was determined by qPCR, the release of adipokines and inflammatory cytokines to the culture media was assessed, and cell respiration was measured. Adipogenesis was not altered by the combined treatment of human adipocytes. However, DTG at the highest dose repressed adipogenesis marker genes expression, and TAF and TDF appeared to mitigate this effect. DTG repressed the expression of adiponectin and the release of adiponectin and leptin in differentiating adipocytes, and these effects were mantained in combination with TAF and TDF. DTG plus TAF or TDF on human adipocytes enhanced inflammation and stress and increased the release of proinflammatory cytokines to the culture media. Together, our results show that combined therapy with these drugs can alter inflammation, cellular stress, and fibrosis in human adipocytes. These findings may improve our understanding and management of the effects of cART on body adiposity and metabolic dysregulation in PLWH.

Bacillus and Streptomyces spp. as hosts for production of industrially relevant enzymes

The application of enzymes is expanding across diverse industries due to their nontoxic and biodegradable characteristics. Another advantage is their cost-effectiveness, reflected in reduced processing time, water, and energy consumption. Although Gram-positive bacteria, Bacillus, and Streptomyces spp. are successfully used for production of industrially relevant enzymes, they still lag far behind Escherichia coli as hosts for recombinant protein production. Generally, proteins secreted by Bacillus and Streptomyces hosts are released into the culture medium; their native conformation is preserved and easier recovery process enabled. Given the resilience of both hosts in harsh environmental conditions and their spore-forming capability, a deeper understanding and broader use of Bacillus and Streptomyces as expression hosts could significantly enhance the robustness of industrial bioprocesses. This mini-review aims to compare two expression hosts, emphasizing their specific advantages in industrial surroundings such are chemical, detergent, textile, food, animal feed, leather, and paper industries. The homologous sources, heterologous hosts, and molecular tools used for the production of recombinant proteins in these hosts are discussed. The potential to use both hosts as biocatalysts is also evaluated. Undoubtedly, Bacillus and Streptomyces spp. as production hosts possess the potential to take on a more substantial role, providing superior (bio-based) process robustness and flexibility. KEY POINTS: • Bacillus and Streptomyces spp. as robust hosts for enzyme production. • Industrially relevant enzyme groups for production in alternative hosts highlighted. • Molecular biology techniques are enabling easier utilization of both hosts.