Associations between vaginal microbiota and endometrial polypoid lesions in women of reproductive age: a cross-sectional study

RESEARCH QUESTION

What are the different characteristics of vaginal microbial composition between patients with endometrial polypoid lesions and controls?

DESIGN

This cohort study compared the pre-operative microbial compositions of vaginal samples in a cohort of 703 women with endometrial polypoid lesions [293 and 410 women diagnosed and not diagnosed with polyps pathologically (polyps group and not-polyps group, respectively] and 703 women in the control group. Bacterial abundance, diversity, differential taxa and microbial network structure were assessed using 16S rRNA gene sequencing. Predictive algorithms were used to determine the functional pathways of vaginal microbiota within the cohort.

RESULTS

The control group exhibited higher relative abundance of Lactobacillus crispatus in comparison with the polypoid lesions group (P = 0.0427). Beta diversity of vaginal microbiota differed significantly between the groups (P < 0.05). Comparing the polyps group with the not-polyps group, Leptotrichia spp. and Cutibacterium spp. were more abundant in the polyps group, and Fannyhessea spp., Acinetobacter spp. and Achromobacter spp. were more abundant in the not-polyps group. The control group exhibited higher abundance of Bifidobacterium spp., Achromobacter spp. and Escherichia/Shigella spp. (false discovery rate < 0.05). Furthermore, the polyps group and not-polyps group displayed more complex co-occurrence networks compared with the control group.

CONCLUSIONS

The results of this study provide compelling evidence supporting associations between vaginal microbiota and endometrial polypoid lesions, highlighting the potential relationship between a well-balanced vaginal microbial ecosystem and a healthy intrauterine environment.

Biosynthesis of Zinc Oxide Nanoparticles by Lactobacillus spp. and Investigation of their Antimicrobial Effect

BACKGROUND

Nanoparticle biology is preferable to other common methods due to its economic efficiency and compatibility with the environment. On the other hand, the prevalence of drug-resistant bacterial strains is expanding and it is necessary to use alternative antibiotic compounds to deal with them. The aim of the present study was the biosynthesis of zinc oxide nanoparticles(ZnO NPs) by Lactobacillus spp. and their antimicrobial effect.

METHODS

In this study, after the biosynthesis of ZnO NPs by Lactobacillus spp, Characterization of Nanoparticulation Was performed by UV-Vis, XRD, and Scanning Electron Microscopy (SEM). Additionally, Lactobacillus spp. - ZnO NPs were assessed for their antimicrobial properties.

RESULTS

UV-visible spectroscopy confirmed the Lactobacillus spp. - ZnO NPs absorbed UV in the region of 300-400 nm. XRD analysis showed the presence of zinc metal in nanoparticles. SEM revealed that Lactobacillus plantarum - ZnO NPs were smaller than the others. Staphylococcus aureus showed the largest non-growth halo diameter against ZnO NPs synthesized by L. plantarum ATCC 8014 (3.7 mm). E. coli had the largest growth halo diameter against ZnO NPs synthesized by L. casei (3 mm) and L. plantarum (2.9 mm). The MIC values of ZnO NPs synthesized by L. plantarum ATCC 8014, L.casei ATCC 39392, L. fermenyum ATCC 9338, L. acidophilus ATCC 4356 were 2,8,8 and 4 μg/mL for Staphylococcus aureus. The MIC values of ZnO NPs synthesized by L. plantarum ATCC 8014, L. casei ATCC 39392, L. fermenyum ATCC 9338, L. acidophilus ATCC 4356 were 2, 4, 4, and 4 μg/ml for E. coli. The lowest MICs were 2 μg/ml for E. coli and S. aureus related to ZnO NPs synthesized by L. plantarum ATCC 8014. MIC and MBC values were equivalent to each other.

CONCLUSION

The results of this research show that ZnO NPs synthesized by L. plantarum ATCC 8014 have more antimicrobial effects than other ZnO NPs used. Therefore, the ZnO NPs made with Lactobacillus plantarum ATCC 8014 have the potential to kill bacteria and can be considered a candidate for antibiotic replacement.

Evaluation of the Efficacy of Lactobacillus acidophilus in the Treatment of Cyclophosphamide-induced Hemorrhagic Cystitis in Wistar Rats

BACKGROUND

Hemorrhagic cystitis is an inflammatory complication that can be caused by the administration of cyclophosphamide, which is widely used as an antineoplastic agent. In the search for new therapeutic alternatives, probiotics can suppress the inflammatory process and, therefore, can be used to prevent this disease.

OBJECTIVE

Thus, this study aimed to evaluate the effects of using Lactobacillus acidophilus NCFM in the treatment of cyclophosphamide-induced hemorrhagic cystitis in Wistar rats.

METHODS

Lactobacillus acidophilus NCFM (2x10⁸ CFU) was used in the treatment of cyclophosphamide- induced hemorrhagic cystitis (200 mg/kg, intraperitoneal) in 77 female Wistar rats. Rats were distributed into experimental groups (n = 9): control group (GC), zero control group (GCZ), inflammation group (GI), 24-hour acute treatment groups: 24-hour lactobacilli treatment group (GL24H) and mesna group (GM), and 30-day chronic treatment groups: lactobacilli treatment group (GTL) and mesna+lactobacilli group (GM+L). After treatment, animals were euthanized and biological materials were collected for blood count, biochemical analyses, examination of abnormal sediment elements (EAS), and histopathological analysis.

RESULTS

GI results showed development of edema, macroscopic alterations, and signs of bleeding in the bladder; in addition, lesions in the urothelium and hemorrhage were also found. GL24H and GM presented intact urothelium, without inflammatory reaction and hematological or biochemical urine alterations.

CONCLUSION

Therefore, this study demonstrated that L. acidophilus presented uroprotective effect against the action of cyclophosphamide in both the short and long term.

Anti-cancer activity of human gastrointestinal bacteria

Malignant neoplasm is one of the most incurable diseases among inflammatory diseases. Researchers have been studying for decades to win over this lethal disease and provide the light of hope to humankind. The gastrointestinal bacteria of human hold a complex ecosystem and maintain homeostasis. One hundred trillion microbes are residing in the gastrointestinal tract of human. Disturbances in the microbiota of human's gastrointestinal tract can create immune response against inflammation and also can develop diseases, including cancer. The bacteria of the gastrointestinal tract of human can secrete a variety of metabolites and bioproducts which aid in the preservation of homeostasis in the host and gut. During pathogenic dysbiosis, on the other hand, numerous microbiota subpopulations may increase and create excessive levels of toxins, which can cause inflammation and cancer. Furthermore, the immune system of host and the epithelium cell can be influenced by gut microbiota. Probiotics, which are bacteria that live in the gut, have been protected against tumor formation. Probiotics are now studied to see if they can help fight dysbiosis in cancer patients undergoing chemotherapy or radiotherapy because of their capacity to maintain gut homeostasis. Countless numbers of gut bacteria have demonstrated anti-cancer efficiency in cancer treatment, prevention, and boosting the efficiency of immunotherapy. The review article has briefly explained the anti-cancer immunity of gut microbes and their application in treating a variety of cancer. This review paper also highlights the pre-clinical studies of probiotics against cancer and the completed and ongoing clinical trials on cancers with the two most common and highly effective probiotics Lactobacillus and Bacillus spp.

Molecular Characterization of Probiotics and Their Influence on Children with Autism Spectrum Disorder

Children with autism spectrum disorder (ASD) are usually unable to express abdominal discomfort properly, and thus gastrointestinal symptoms (GIS) are sometimes shadowed by aggression, which is sometimes misunderstood as a behavioral characteristic of ASD. Several studies have reported interesting correlations between the severity of behavioral and gastrointestinal symptoms in ASD children. The present study aimed to investigate the potential effects of probiotics as an adjuvant therapy to modulate the clinical status of ASD children. This study included 40 children with ASD aged 2-5 years. The feeding product was prepared from whey powder (without casein) and some minced cooked yellow vegetables in adequate ratios fortified with the studied probiotic strains (Bifidobacterium spp. and Lactobacillus spp.). Bifidobacterium strains were assessed from stool samples of children with ASD. Bifidobacterium strains were analyzed in the stools of ASD children. Recruited ASD patients received 10 g of the nutritional supplement once a day for 3 months. Childhood Autism Rating Scale (CARS) and Autism Diagnostic Interview-Revised (ADIR) were reevaluated clinically. Questionnaire on Pediatric Gastrointestinal Symptoms-Rome III Version was used for all children with ASD before and after. There is a significant increase in the colony counts of both Bifidobacterium spp. and Lactobacillus spp., which present in the stool of ASD children after probiotic supplementation for 3 months. It was highly significant in the case of Bifidobacterium spp. (p value 0.000) and a significant increase in Lactobacillus spp. (p value 0.015). The present study showed reduced anxiety and observation of deep sleep for children with ASD (80%) after taking the supplementation. This indicates that probiotics may have a potential effect in reducing symptoms and severity of ASD and in correcting dysbiosis.

Biovalorisation of spent Konacha tea leaves via single-culture fermentation involving wine yeasts and lactic acid bacteria

AIMS

The objective of this study was to explore the potential of fermentation as a biovalorisation strategy for spent tea leaves (STL), a major agri-food waste generated from the tea extraction industry. Fermentation by wine yeasts or lactic acid bacteria (LAB) have shown promising results in previous studies across various substrates.

METHODS AND RESULTS

Konacha (green tea) STL slurries were inoculated with single strains of wine yeasts or LAB, respectively. After a 48-h fermentation, changes in selected non-volatile and volatile compositions were evaluated. Fermentation by LAB increased organic acid content by 5- to 7-fold (except Lactobacillus fermentum) and modulated the composition of major tea catechins, while wine yeast fermentation resulted in a 30% increase in amino acid content. Strain-specific production of specific volatile compounds was also observed, such as butanoic acid (L. fermentum), isoamyl acetate (Pichia kluyveri) and 4-ethylphenol (L. plantarum).

CONCLUSIONS

Both volatile and non-volatile compound compositions of Konacha STL were successfully modified via wine yeast and LAB fermentation.

SIGNIFICANCE AND IMPACT OF STUDY

Our findings indicate that Konacha STL is a suitable medium for biovalorisation by wine yeasts or LAB via the generation of commercially useful volatile and non-volatile compounds. Future optimizations could further render fermentation an economically viable strategy for the upcycling of STL.

In vitro evaluation of the probiotic potential of Lactobacillus isolated from native swine manure

Background and Aim:

Using antimicrobials as a feed additive in swine production is prohibited because it is a major cause of the emergence of antimicrobial-resistant bacteria. Probiotics such as Lactobacillus spp. are an attractive alternative to reduce antimicrobial resistance and promote swine growth. This study aimed to evaluate the in vitro probiotic properties of Lactobacillus isolated from indigenous swine manure.

Materials and Methods:

A total of 30 fecal samples from healthy individual indigenous pigs were collected and isolated on de Man, Rogosa, and Sharpe agar. The preliminary screen identified candidates with antibacterial activity against six pathogens and >50% survival and tolerance to acid (pH 3.0) and 1% bile salt. Isolates that passed the initial screen will be tested for other probiotic properties.

Results:

Of the 314 isolates from 30 pig manure samples, 17 isolates satisfied all initial conditions for probiotic properties. Each isolate has unique, distinctive properties. Isolates B4, B5, B8, B17, B87, and B144 formed thick biofilms, whereas isolates B5, B8, and 27 adhered well to the intestinal wall and exhibited strong autoaggregation properties. Isolate B4 aggregated with Enterohemorrhagic Escherichia coli and Enteropathogenic E. coli. Tests in pH-adjusted cell-free medium indicated that the antibacterial activity resulted from bacterial acidification rather than bacteriocin formation. Sequence analysis (16S rRNA) revealed 16 of the isolates were Lactobacillus plantarum, and only one isolate was Lactobacillus salivarius.

Conclusion:

We isolated 17 Lactobacillus from swine manure and demonstrated that their probiotic properties might be useful as a probiotic cocktail for swine feed.

Bacteriocins, A Natural Weapon Against Bacterial Contamination for Greater Safety and Preservation of Food: A Review

Nowadays, consumers have become increasingly attentive to human health and the use of more natural products. Consequently, the demand for natural preservatives in the food industry is more frequent. This has led to intense research to discover new antimicrobial compounds of natural origin that could effectively fight foodborne pathogens. This research aims to safeguard the health of consumers and, above all, to avoid potentially harmful chemical compounds. Lactobacillus is a bacterial genus belonging to the Lactic Acid Bacteria and many strains are defined GRAS, generally recognized as safe. These strains are able to produce substances with antibacterial activity against food spoilage bacteria and contaminating pathogens: the bacteriocins. The aim of this review was to focus on this genus and its capability to produce antibacterial peptides. The review collected all the information from the last few years about bacteriocins produced by Lactobacillus strains, isolated from clinical or food samples, with remarkable antimicrobial activities useful for being exploited in the food field. In addition, the advantages and disadvantages of their use and the possible ways of improvement for industrial applications were described.

Probiotic capability of novel lactic acid bacteria isolated from worker honey bees gut microbiota

The study aimed to evaluate the probiotic and safety properties of lactic acid bacterial (LAB) strains isolated from the gut microbiota of honey bee Apis mellifera L., since this source remains a promising reservoir of microbial diversity. A total of five bacterial isolates were molecularly identified using 16S rRNA gene sequencing as Enterococcus faecalis-HBE1, Lactobacillus brevis-HBE2, Enterococcus faecalis-HBE3, Enterococcus faecalis-HBE4 and Lactobacillus casei-HBE5. Gut tolerance conditions (low pH and bile salt) were evaluated. Exopolysaccharides (EPS) production, hemolytic, antioxidant activity, resistance toward antibiotics and technological characteristics (starter activity, pH and proteolysis) were examined. The five isolates showed a high survival rate (>95%), under gastrointestinal tract conditions indicating excellent potential for application as probiotics. The isolates showed no hemolytic activities and good acidification rates in the range of pH 4.6-4.98 after incubation at 37°C for 24h. The isolates exhibited promising proteolytic activity as well as DPPH radical scavenging activity in the range of 16.52-59.39%. All the tested isolates had the capability to produce exopolysaccharides except Lactobacillus casei-HBE5. These results put forward that lactic acid bacterial strain isolated from honey bee workers can be considered as promising candidates for future applications as starter cultures and could constitute new potential probiotics for the production of functional dietary products promoting health benefits.

Growth and adhesion inhibition of pathogenic bacteria by live and heat-killed food-origin Lactobacillus strains or their supernatants

The study aimed to evaluate qualitatively and quantitatively the antimicrobial capacity of 10 potential probiotic Lactobacillus strains against model enteropathogens and spoilage microorganisms. The probiotic strains (live and heat-killed forms) were also assessed for their ability to inhibit adhesion of selected pathogens to Caco-2 cells. The largest inhibition zones (the diffusion method) were connected with the usage of whole bacteria cultures (WBC), also high and moderate with cell-free supernatant (CFS) and the lowest with cell-free neutralized supernatant (CNS). The highest antagonistic activity of Lactobacillus strains was observed against L. monocytogenes strains, moderate activity against Salmonella, Shigella, Escherichia coli, Pseudomonas and, the lowest against S.aureus, Bacillus and Enterococcus. The inhibition of adhesion to Caco-2 cells was very high in the case of E. coli, Salmonella and L. monocytogenes, and moderate in the case of S.aureus. On average, the inhibition effect was higher when pathogenic bacteria were treated by WBC, than heat-killed Lactobacillus. Although, in most samples, the effect was not significantly different (P> 0.05). The strains Lb. brevis O24 and Lb. rhamnosus K3 showed the biggest overall antimicrobial properties, and were most effective in adherence inhibition of investigated indicator strains. These bacteria or their metabolites can be used for the production of various foods or pharmaceutical products.

A specific bacterial DNA signature in the vagina of Australian women in midpregnancy predicts high risk of spontaneous preterm birth (the Predict1000 study)

BACKGROUND

Intrauterine infection accounts for a quarter of the cases of spontaneous preterm birth; however, at present, it is not possible to efficiently identify pregnant women at risk to deliver preventative treatments.

OBJECTIVE

This study aimed to establish a vaginal microbial DNA test for Australian women in midpregnancy that will identify those at increased risk of spontaneous preterm birth.

STUDY DESIGN

A total of 1000 women with singleton pregnancies were recruited in Perth, Australia. Midvaginal swabs were collected between 12 and 23 weeks' gestation. DNA was extracted for the detection of 23 risk-related microbial DNA targets by quantitative polymerase chain reaction. Obstetrical history, pregnancy outcome, and demographics were recorded.

RESULTS

After excluding 64 women owing to losses to follow-up and insufficient sample for microbial analyses, the final cohort consisted of 936 women of predominantly white race (74.3%). The overall preterm birth rate was 12.6% (118 births); the spontaneous preterm birth rate at <37 weeks' gestation was 6.2% (2.9% at ≤34 weeks' gestation), whereas the preterm premature rupture of the membranes rate was 4.2%. No single individual microbial target predicted increased spontaneous preterm birth risk. Conversely, women who subsequently delivered at term had higher amounts of Lactobacillus crispatus, Lactobacillus gasseri, or Lactobacillus jensenii DNA in their vaginal swabs (13.8% spontaneous preterm birth vs 31.2% term; P=.005). In the remaining women, a specific microbial DNA signature was identified that was strongly predictive of spontaneous preterm birth risk, consisting of DNA from Gardnerella vaginalis (clade 4), Lactobacillus iners, and Ureaplasma parvum (serovars 3 and 6). Risk prediction was improved if Fusobacterium nucleatum detection was included in the test algorithm. The final algorithm, which we called the Gardnerella Lactobacillus Ureaplasma (GLU) test, was able to detect women at risk of spontaneous preterm birth at <37 and ≤34 weeks' gestation, with sensitivities of 37.9% and 44.4%, respectively, and likelihood ratios (plus or minus) of 2.22 per 0.75 and 2.52 per 0.67, respectively. Preterm premature rupture of the membranes was more than twice as common in GLU-positive women. Adjusting for maternal demographics, ethnicity, and clinical history did not improve prediction. Only a history of spontaneous preterm birth was more effective at predicting spontaneous preterm birth than a GLU-positive result (odds ratio, 3.6).

CONCLUSION

We have identified a vaginal bacterial DNA signature that identifies women with a singleton pregnancy who are at increased risk of spontaneous preterm birth and may benefit from targeted antimicrobial therapy.

In vitro assessment of antibacterial activity from Lactobacillus spp. strains against virulent Salmonella species isolated from slaughter animals in Benin

Background and Aim:

Salmonella spp. are among the world’s leading foodborne pathogens, found naturally in the intestines of many animals. Lactic acid bacteria, mainly Lactobacillus, are a promising alternative to antibiotics for animal and human health. This study aimed to assess the in vitro antibacterial activity of Lactobacillus spp. strains against virulent Salmonella spp. isolated from slaughter animals in Benin.

Materials and Methods:

Eleven samples of raw cow’s milk, five samples of breast milk, and six infant stool samples were taken. From these samples, strains of Lactobacillus were isolated and identified. The probiotic potential of each of the identified strains was characterized, and finally in vitro antibacterial activity of these strains was evaluated against three virulent strains of Salmonella spp. and a reference strain of Salmonella Typhimurium ATCC 14028.

Results:

Out of the 22 samples collected, 20 strains of Lactobacillus spp. were isolated and identified. These strains included Lactobacillus plantarum (30%), Lactobacillus delbrueckii (25%), Lactobacillus casei (25%), Lactobacillus salivarius (15%), and Lactobacillus acidophilus (05%). Characterization of the probiotic potential of these strains showed that only 16 strains were resistant to pH=1.5. Fourteen of them were able to withstand the simulated gastric juice (pH 1.5+pepsin). The 14 probiotic strains showed very good antibacterial activity against virulent strains of Salmonella spp. with inhibition zone diameters ranging from 12.36±0.03 mm to 35.33±0.05 mm (R values>6 mm).

Conclusion:

From this study, Lactobacillus strains isolated from raw cow milk, breast milk, and infantile stool might be used as some valid candidates for probiotics. It also represents good alternatives for antibiotics in the fight against animal and human salmonellosis.

Longitudinal Evaluation of Salivary Iga-S in Children with Early Childhood Caries Before and After Restorative Treatment

Background: Our aim was to compare salivary levels of secretory immunoglobulin A (s-IgA) in children with early childhood caries (ECCG) and those who are caries-free (CFG) and verify these levels in a follow-up period after restorative treatment. Materials and methods: We selected 46 systemically healthy children in the complete primary dentition period, who were allocated into two groups: CFG (n = 23) and ECCG (dmf-s > 0; n = 23). Unstimulated whole saliva was obtained at baseline from both groups and during the follow-up period (7 days, 1, 2 and 3 months) in the ECCG group. The s-IgA was measured using an ELISA assay, and total protein was assessed using the Bradford method. We also evaluated the flow rate (mL/min), Streptococcus mutans and Lactobacillus spp. counting using selective media plaques. The data were submitted to statistical analysis using the software SPSS 20.0 (SPSS Inc, IL, USA) with a confidence interval set at 95%. Results: Salivary s-IgA levels were higher in baseline of ECCG than in CFG (p<0.05). No statistically significant differences were observed between s-IgA salivary levels at baseline and the evaluations after dental treatment in ECCG (p>0.05). However, we observed two different changes in s-IgA levels among participants: one group presented s-IgA reduction, and the other group demonstrated its maintenance. It was shown that patients from the ECCG group who presented a reduction in s-IgA levels during follow-up also showed a decrease in Streptococcus mutans and Lactobacillus spp. count (p<0.05), in contrast to patients who did not present this reduction. The flow rate and total protein were similar between groups (p>0.05). Conclusions: The present data support the idea that children with early childhood caries present higher levels of s-IgA in saliva than caries-free children. The restorative dental treatment does not have a significant influence on salivary levels of this immunoglobulin during the follow-up period.

Production of Dextran from Locally Lactobacillus Spp. Isolates

BACKGROUND

Dextran is a commercially available bacterial exopolysaccharide (EPS) with several industrial applications in the food industry and in the biomedical industry as an adjuvant, emulsifier, carrier, and stabilizer. The production of dextran at the industrial level occurs through the fermentation of a sucrose-rich medium. Research to optimize dextran production has found that the yield of dextran varies depending the specific conditions for production. The aim of this study was to produce dextran and establish the optimal conditions for dextran biosynthesis from different Lactobacillus species isolated from healthy vaginal and infant stool samples.

METHODS

Lactobacillus spp. were isolated and identified from vaginal and infant stool samples via the VITEK 2 system. The presence of dextran biosynthesis from the different Lactobacillus spp. isolates was determined by a screening test for mucoid colonies and confirmed via the ethanol precipitation method. To optimize for the maximum yield of dextran, the effects of various parameters such as temperature, incubation time, pH, inoculum size, aeration, and sucrose concentration were examined.

RESULTS

All Lactobacillus spp. isolates were able to produce dextran. The optimal conditions for dextran production was at 24 hours of incubation at 30 °C with 15% sucrose, 4% inoculation size at pH 7.0 in aerobic conditions. This yielded a dextran dry weight of 580 mg/100 mL.

CONCLUSION

Dextran production from Lactobacillus species isolates vagina and infant stool had the ability to produce dextran.

Lactobacillus species increase the survival of Galleria mellonella infected with Candida albicans and non-albicans Candida clinical isolates

Investigation into new therapeutic strategies, such as the use of bacterial isolates with probiotic characteristics, has increased in importance due to the high incidence of Candida albicans and non-albicans Candida infections. This study evaluates Lactobacillus paracasei, Lactobacillus fermentum and Lactobacillus rhamnosus strains as prophylactic and therapeutic agents against infection caused by Candida albicans, Candida glabrata, Candida krusei, and Candida tropicalis in a Galleria mellonella model. Prophylactic treatment provided greater benefits during Candida spp. infection, increasing G. mellonella survival, compared to therapeutic treatment. This study demonstrated that the different Lactobacillus species are potent prophylactic agents of Candida species infection.

Characterization and transfer of antimicrobial resistance in lactic acid bacteria from fermented dairy products in China

INTRODUCTION

Lactic acid bacteria (LAB) are commonly found in foods and are also natural intestinal inhabitants in humans and most animals. However, information regarding antimicrobial resistance and the transfer of resistance genes of LAB from fermented dairy products in China is limited.

METHODOLOGY

In this study, LAB isolates (n = 82) of Lactobacillus (n = 43) and Streptococcus thermophilus (n = 39) were isolated from 51 commercial fermented food samples in China. All isolates were subjected to pulsed-field gel electrophoresis (PFGE), antimicrobial susceptibility, detecting resistance genes, as well as investigating the transferability of resistance genes.

RESULTS

The 43 Lactobacillus isolates yielded 24 PFGE patterns and the 34 isolates of S. thermophilus generated 32 different PFGE patterns. Among the 43 Lactobacillus strains, the most commonly observed resistance was that to streptomycin (83.7%) and gentamycin (83.7%). Among the 39 S. thermophilus strains, the most frequently observed resistance was that to streptomycin (92.3%), gentamycin (87.2%), ciprofloxacin (79.5%), and chloramphenicol (71.8%), whereas the lowest level of resistance was that against erythromycin (7.7%). Antimicrobial resistance genes for erythromycin (emrB), gentamycin (aac(6')-aph(2")), streptomycin (ant(6)), sulfamethoxazole (sulI and sulII), tetracycline (tetM and tetS) were detected in the 18 resistance LAB strains. Conjugation experiments showed that tetM from L. delbrueckii subsp. bulgaricus R6 and tetS from L. plantarum R41 were successfully transferred to L. monocytogenes by filter mating.

CONCLUSIONS

LAB strains could potentially act as reservoirs of resistance genes and play an active role in the transfer of resistance to humans via the food chain.

The effects of inulin and fructo-oligosaccharide on the probiotic properties of Lactobacillus spp. isolated from human milk

This study aims to determine the effects of inulin and fructo-oligosaccharide (FOS) on the probiotic properties of five Lactobacillus spp. isolated from human milk. Lactobacillus spp. were isolated and identified, and the growth characteristics, acid and bile salt tolerance, antagonistic effects, and cholesterol assimilation of Lactobacillus strains were investigated in the presence of inulin and FOS. Lactobacillus casei L1 was able to utilize inulin and FOS as carbon source as well as glucose even other strains were able to use, including Lactobacillus rhamnosus GG. This strain also showed high tolerance to acid and bile salt, even at pH 2.5 and 0.5% bile salt levels, respectively. Inulin and FOS promoted the antimicrobial activity of L. casei L1 against pathogenic bacteria. Cholesterol assimilation was higher than in the other and control probiotic strains in the presence inulin and FOS, which were measured as 14 and 25 mg/dL, respectively. In conclusion, L. casei L1 can use both inulin and FOS to maintain its viability both at digestive conditions and also the relevant prebiotics, and show broad antagonistic activity and cholesterol assimilation.

Fermented liquid feed for pigs: an ancient technique for the future

Fermented liquid feed is feed that has been mixed with water at a ratio ranging from 1:1.5 to 1:4. By mixing with water, lactic acid bacteria and yeasts naturally occurring in the feed proliferate and produce lactic acid, acetic acid and ethanol which reduces the pH of the mixture. This reduction in pH inhibits pathogenic organisms from developing in the feed. In addition, when this low pH mixture is fed, it reduces the pH in the stomach of pigs and prevents the proliferation of pathogens such as coliforms and Salmonella in the gastrointestinal tract. For piglets, the use of fermented liquid feed offers the possibility of simultaneously providing feed and water, which may facilitate an easier transition from sow’s milk to solid feed. Secondly, offering properly produced fermented liquid feed may strengthen the role of the stomach as the first line of defense against possible pathogenic infections by lowering the pH in the gastrointestinal tract thereby helping to exclude enteropathogens. Finally, feeding fermented liquid feed to pigs has been shown to improve the performance of suckling pigs, weaner pigs and growing-finishing pigs. In this review, current knowledge about the use of fermented liquid feed in pig diets will be discussed. This will include a discussion of the desirable properties of fermented liquid feed and factors affecting fermentation. In addition, advantages and disadvantages of fermented liquid feed will be discussed including its effects on gastrointestinal health, intestinal pH and the types of bacteria found in the gastrointestinal tract as well as the effects of fermented liquid feeds on pig performance.

Enhancement of survival of alginate-encapsulated Lactobacillus casei NCDC 298

BACKGROUND

Micro-encapsulation of hydrocolloids improves the survival of sensitive probiotic bacteria in the harsh conditions that prevail in foods and during gastrointestinal passage by segregating them from environments. Incorporation of additives in encapsulating hydrocolloids and coatings of microcapsules further improves the survival of the probiotics. In this study, the effect of incorporation of resistant-maize starch in alginate for micro-encapsulation and coating of microcapsules with poly-l-lysine, stearic acid and bees wax on the survival of encapsulated Lactobacillus casei NCDC 298 at pH 1.5, 2% high bile salt, 65 °C for 20 min and release of viable lactobacilli cells from the capsule matrix in simulated aqueous solutions of colonic pH were assessed.

RESULTS

Addition of resistant maize starch (2%) improved the survival of encapsulated L. casei NCDC 298. Coating of microcapsules with poly-L-lysine did not further improve the protection of encapsulated cells from the harsh conditions; however, bees wax and stearic acid (2%) improved the survival under similar conditions. Incorporation of maize starch (2%) in alginate followed by coating of beads with stearic acid (2%) led to better protection and complete release of entrapped lactobacilli in simulated colonic pH solution was observed.

CONCLUSION

Additional treatments improve the survival of alginate-encapsulated lactobacilli cells without hindering the release of active cells from the capsule matrix and hence, the resulting encapsulated probiotics can be exploited in the development of probiotic functional foods with better survival of sensitive probiotic organisms.