Genome-wide genetic architecture for plant maturity and drought tolerance in diploid potatoes

Cultivated potato (Solanum tuberosum) is known to be highly susceptible to drought. With climate change and its frequent episodes of drought, potato growers will face increased challenges to achieving their yield goals. Currently, a high proportion of untapped potato germplasm remains within the diploid potato relatives, and the genetic architecture of the drought tolerance and maturity traits of diploid potatoes is still unknown. As such, a panel of 384 ethyl methanesulfonate-mutagenized diploid potato clones were evaluated for drought tolerance and plant maturity under field conditions. Genome-wide association studies (GWAS) were conducted to dissect the genetic architecture of the traits. The results obtained from the genetic structure analysis of the panel showed five main groups and seven subgroups. Using the Genome Association and Prediction Integrated Tool-mixed linear model GWAS statistical model, 34 and 17 significant quantitative trait nucleotides (QTNs) were found associated with maturity and drought traits, respectively. Chromosome 5 carried most of the QTNs, some of which were also detected by using the restricted two-stage multi-locus multi-allele-GWAS haploblock-based model, and two QTNs were found to be pleiotropic for both maturity and drought traits. Using the non-parametric U-test, one and three QTNs, with 5.13%-7.4% phenotypic variations explained, showed favorable allelic effects that increase the maturity and drought trait values. The quantitaive trait loci (QTLs)/QTNs associated with maturity and drought trait were found co-located in narrow (0.5-1 kb) genomic regions with 56 candidate genes playing roles in plant development and senescence and in abiotic stress responses. A total of 127 potato clones were found to be late maturing and tolerant to drought, while nine were early to moderate-late maturing and tolerant to drought. Taken together, the data show that the studied germplasm panel and the identified candidate genes are prime genetic resources for breeders and biologists in conventional breeding and targeted gene editing as climate adaptation tools.

Antibacterial Effect of Pomegranate Juice on Listeria innocua and E. coli in Different Media

The antibacterial effect of pomegranate juice (PJ) at six concentrations (0, 10, 20, 30, 40, and 50%) against Listeria innocua and Escherichia coli was investigated in distilled water (DW) and bacterial culture broth. L. innocua and E. coli at approximately 105 cfu mL-1 were inoculated in PJ samples and incubated at 4, 25, and 37 °C for 0, 6, 24, and 48 h. The bacterial population and pH of culture media were measured at each removal. Results indicated that the antibacterial effect of PJ was dependent upon bacteria species, juice concentration, incubation temperature, and growth medium. Higher juice concentration and incubation temperature resulted in increased antibacterial effects. Bacterial populations were decreased more significantly in DW systems than in the culture broth, while L. innocua was more sensitive to PJ than E. coli in the DW systems. Regardless of PJ concentrations in DW systems, L. innocua, initially inoculated at approximately 105 cfu mL-1, was reduced to undetectable levels at 25 and 37 °C within 24 h. The growth of L. innocua and E. coli was significantly inhibited in bacterial culture broth containing ≥ 20% PJ (p < 0.001). This study provides insight into the potential application of PJ in food and beverage products for food protection.

Tracking the development of the superficial scald disorder and effects of treatments with diphenylamine and 1-MCP using an untargeted metabolomic approach in apple fruit

Superficial scald is a physiological storage disorder that significantly reduces the marketability of apple fruit. To gain fundamental knowledge about the biochemical pathways leading to the development of the disorder and mechanisms of treatments for prevention, an untargeted metabolomics experiment employing liquid chromatography and mass spectrometry with data independent acquisition was performed. Metabolomic changes of two apple cultivars 'Cortland' and 'Red Delicious' with scald development and scald control treatments, using diphenylamine and 1-MCP, at 0-1 °C for up to 7 months was investigated. In total, 833 features/compounds were analyzed, and among them 59 were found to change significantly in controls involved in scald development, and in response to DPA and 1-MCP treatments. Our results provide new evidence that metabolites in association with phenylpropanoid metabolism, antioxidant and redox systems, and amino acid metabolism are related closely to scald development and response to potential treatments.

Effect of natural antimicrobial agent (MicroGARD) combined with edible coating (NatureSeal) treatment on fresh-cut butternut squash

To improve fresh-cut produce quality and shelf life, 0.5% or 1.0% MicroGARD^® 730 (MG) as a natural alternative to synthetic chemical preservatives, 2.5% NatureSeal^® (NS) product (vitamin/mineral-based blends), 0.5% MG combined with 2.5% NS, and 1% MG combined with 2.5% NS were used to treat fresh-cut butternut squash (Cucurbita moschata). The 240 g samples were put into food grade bags and stored at 4 or 7 °C. Microbial population, including aerobic plate counts (APCs), yeast and molds, total coliforms, and quality parameters, including head space O₂ /CO₂ concentration in package, pH, soluble solids, color, and conductivity, were evaluated after 0, 3, 6, 9, 12, and 20 days of storage. Results showed that after 6 days of storage at 7 °C, APC of check and control samples reached to 2.6 × 10⁸ and 1.5 × 10⁷ CFU/g, respectively; while they were kept at 10⁴ CFU/g (3 to 4 log reduction) in the squash samples treated with 0.5% or 1% MG combined with NS at 7 °C. Similar results were found on squash samples stored at 4 °C for 9 days. The cut squash treated with MG combined with NS had APC ≤ 10⁷ CFU/g at 4 °C for about 20 days compared to 9 days in controls or 0.5% MG-treated samples, and 12 days in 1% MG-treated or NS-treated samples, respectively. Considering overall quality and extended shelf life, MG combined with NS was recommended to apply to cut squashes stored at 4 °C. PRACTICAL APPLICATION: This research provided useful information and practical treatment application for developing fresh-cut produce with good quality and extended shelf life up to 20 days at 4 °C.

Proteomic Changes in Antioxidant System in Strawberry During Ripening

To investigate the strawberry antioxidant defense system during fruit ripening, a targeted quantitative proteomic approach using multiple reaction monitoring (MRM) was developed to investigate targeted proteins in the antioxidant enzyme system in strawberry fruit. We investigated 46 proteins and isoforms with 73 identified peptides which may be involved in this antioxidant enzyme system. Among the proteins that changed during ripening, aldo/keto reductase (AKR), superoxide dismutase (SOD) and glutathione transferase (GT) increased significantly, while dehydroascorbate reductase, 2-Cys peroxiredoxin, catalase (CAT), 1-Cys peroxiredoxin and L-ascorbate peroxidase (APX) decreased significantly. These results suggest that fruit ripening of strawberry activates the enzymes of an SOD/glutathione metabolism system. The methodologies used in this study will be useful for systematically characterizing the role of antioxidant enzymes in fruit ripening of other plants.

Comparative transcriptome expression analysis in susceptible and resistant potato (Solanum tuberosum) cultivars to common scab (Streptomyces scabies) revealed immune priming responses in the incompatible interaction

Common scab disease in potato has become a widespread issue in major potato production areas, leading to increasing economic losses. Varietal resistance is seen as a viable and long-term scab management strategy. However, the genes and mechanisms of varietal resistance are unknown. In the current study, a comparative RNA transcriptome sequencing and differential gene signaling and priming sensitization studies were conducted in two potato cultivars that differ by their response to common scab (Streptomyces scabies), for unraveling the genes and pathways potentially involved in resistance within this pathosystem. We report on a consistent and contrasted gene expression pattern from 1,064 annotated genes differentiating a resistant (Hindenburg) and a susceptible (Green Mountain) cultivars, and identified a set of 273 co-regulated differentially expressed genes in 34 pathways that more likely reflect the genetic differences of the cultivars and metabolic mechanisms involved in the scab pathogenesis and resistance. The data suggest that comparative transcriptomic phenotyping can be used to predict scab lesion phenotype in breeding lines using mature potato tuber. The study also showed that the resistant cultivar, Hindenburg, has developed and maintained a capacity to sense and prime itself for persistent response to scab disease over time, and suggests an immune priming reaction as a mechanism for induced-resistance in scab resistant potato cultivars. The set of genes identified, described, and discussed in the study paves the foundation for detailed characterizations towards tailoring and designing procedures for targeted gene knockout through gene editing and phenotypic evaluation.

Metabolic Profile of Strawberry Fruit Ripened on the Plant Following Treatment With an Ethylene Elicitor or Inhibitor

Strawberry is the most studied nonclimacteric fruit for understanding the role ethylene has in ripening regulation. However, previous studies on the effects of ethylene on strawberry ripening were conducted with detached fruit. Thus, the aim of this work was to determine the effect of ethylene and the ethylene-action inhibitor 1-methylcyclopropene (1-MCP) applied at different developmental stages on important physical-chemical attributes of ripe 'Albion' strawberry. Fruit at four developmental stages that remained attached to the plant were dipped in one of three treatment solutions (Ethephon, 1-methylcyclopropene, and water), plus one absolute control that received no dip. Following treatment, when immature fruit were fully red or 24 h after treatment for red-treated fruit, strawberry fruit were assessed for physicochemical properties (mass, length, diameter, firmness, color, titratable acidity, soluble solids, pH, total phenolics, sugar, organic acid, amino acid, and volatile composition). The days following treatment required for fruit to ripen were also recorded. Treatments did not affect the rate of ripening nor fruit color, titratable acidity, pH, soluble solids, total phenolics, sugars, or organic acids of ripe fruit. Ethephon affected fruit mass, diameter, length, firmness, anthocyanins, amino acids, and volatiles, but these effects were dependent on fruit developmental stage at which the treatment was applied. When green fruit were treated with ethephon, ripe fruit had larger diameter and mass. Ethephon treatment of white fruit resulted in ripe fruit having greater anthocyanin content. Treatment of pink fruit resulted in ripe fruit having smaller diameter, length, and mass and greater firmness. Treatment of red fruit with ethephon altered fruit volatile composition, increasing concentrations of ethyl- and acetate-esters, which were reduced by the 1-MCP treatment. Ethephon treatment increased concentrations of 11 of the 19 free amino acids measured in ripe fruit with treatment of green and white fruit having the greatest effect. A total of 41 volatile compounds had significant correlations with 14 amino acids. While ethylene did not stimulate typical ripening of strawberry fruit, it does appear to alter fruit development and metabolism. The physiological effects of ethylene on strawberry fruit appear to depend on the developmental stage of the fruit.

Reaction of Surrogate Escherichia coli Serotype O157:H7 and Non-O157 Strains to Nutrient Starvation: Variation in Phenotype and Transcription of Stress Response Genes and Behavior on Lettuce Plants in the Field

Preharvest contamination with bacteria borne by irrigation water may result in leafy vegetables serving as vehicles for transmission of Shiga toxin-producing Escherichia coli (STEC) to humans. The influence of starvation-associated stress on the behavior of non-toxin-producing strains of E. coli serotype O157:H7 and serotypes O26, O103, O111, and O145 was examined subsequent to their introduction to the phyllosphere of field-grown romaine lettuce as inocula simulating starved (96 h in sterile deionized water) and nutrient-depleted (24 h broth culture) cells. As with E. coli O157:H7, leaf populations of the non-O157 strains declined rapidly during the first 72 h postinoculation, displaying the biphasic decay curve typical of serotype O157:H7 isolates. Preinoculation treatment appeared not to influence decay rates greatly (P > 0.5), but strain-specific differences (persistence period and attachment proficiency) indicated that serotype O103:H2 strain PARC445 was a better survivor. Also assessed was the impact of preinoculation treatment on phenotypes key to leaf colonization and survival and the expression of starvation stress-associated genes. The 96-h starvation period enhanced biofilm formation in one strain but reduced motility and autoinducer 2 formation in all five study strains relative to those characteristics in stationary-phase cells. Transcription of rpoS, dps, uspA, and gapA was reduced significantly (P < 0.05) in starvation-stressed cells relative to that for exponential- and stationary-phase cultures. Strain-specific differences were observed; serotype O103:H2 PARC445 had greater downturns than did serotype O157:H7 and other non-O157 strains. Within this particular cohort, the behavior of the representative serotype O157:H7 strain, PARC443 (ATCC 700728), was not predictive of behavior of non-O157 members of this STEC group.

Impact of Listeria Inoculation and Aerated Steam Sanitization on Volatile Emissions of Whole Fresh Cantaloupes

Rapid methods to detect bacterial pathogens on food and strategies to control them are needed to mitigate consumer risk. This study assessed volatile emissions from whole cantaloupe melons (Cucumis melo) as an indicator of Listeria contamination and in response to steam vapor decontamination. Cantaloupe were inoculated with Listeria innocua, a nonpathogenic surrogate for L. monocytogenes, then exposed to 85 °C steam for 240 s (4 min) followed by rapid chilling and storage for 0, 7, 10, or 14 days at 4, 7, or 10 °C. Volatile emissions from whole melons were collected on Carbopack B/Carboxen 1000 headspace collection tubes and analyzed by gas chromatography-mass spectroscopy following thermal desorption. Introduction of L. innocua to cantaloupe rind resulted in a reduction of aromatic compound emission. However, this response was not unique to Listeria contamination in that steam vapor treatment also reduced emission of these compounds. As well, steam vapor treatment diminished the number of viable Listeria and indigenous microflora while causing physiological injury to melon rind. Heat treatment had no significant effects on flesh firmness, color, titratable acidity, or soluble solids, but the production of typical aroma volatiles during postharvest ripening was inhibited. No unique volatile compounds were detected in Listeria contaminated melons. While changes in volatile emissions were associated with Listeria inoculation, they could not be differentiated from heat treatment effects. Results indicate that volatile emissions cannot be used as a diagnostic tool to identify Listeria contamination in whole cantaloupe melons.

PRACTICAL APPLICATION

The detection of pathogen contamination on fresh produce is a continuing challenge. Using a nondestructive screening method, the presence of surrogate Listeria innocua on fresh whole cantaloupes was shown to alter the emissions of aromatic volatiles from whole cantaloupes. However, these altered emissions were not found to be unique to Listeria spp. and therefore cannot be used as a definitive indicator of Listeria contamination.

Microbial Quality and Shelf Life of Blueberry Purée Developed Using Cavitation Technology

Blueberry purée was developed using hydrodynamic cavitation technology. The product was made from entire blueberries without adding any food additives. In this study, microbial reduction following each processing stage (at the industry setting) and after product pasteurization at 86, 88, 90, 92, 94, and 96 °C was investigated. Microbial quality including total plate counts, yeast and molds, and heat-resistant molds counts was determined. Shelf life of pasteurized products stored for up to 24 weeks at room temperature were assessed for microbial quality, soluble solids (°Brix), titratable acidity (citric acid %), pH, viscosity (cP) and flow rate (cm/30 s). Our results indicated that heat-resistant molds, initially present in frozen blueberries with counts at 2.03 log CFU/200g, were totally inactivated at 94 to 96 °C with 1 to 2 min holding time. Shelf life study showed that no product spoilage was caused by bacteria, yeasts and heat-resistant molds along with non-significant changes of textural characteristics. This study provided useful information for the food industry to develop variety of fruit purée products with no wastes of fruit materials.

PRACTICAL APPLICATION

This study provides useful information for the food industry to develop safe liquid food products using cavitation technology without wasting any raw materials.

Characterization of laccase from apple fruit during postharvest storage and its response to diphenylamine and 1-methylcyclopropene treatments

To gain better understanding on laccase in apples and reveal its role in browning color formation during storage, laccases in apples were investigated. The full-length complementary DNAs encoding laccase genes were obtained from different tissues of apple including flowers, calyx, leaves and fruit peel of 'Red Delicious' and 'Cortland'. The apple laccases were compared to those in other plant species and found to have up to 99% homology to Arabidopsis and litchi. qRT-PCR analysis revealed changes in transcript abundance of LAC genes (2, 7, 9, 12, 14, 15 and 16) during storage and in response to DPA and 1-MCP treatments. Enzyme activity of laccase protein in apple peel increased with storage in control fruit, while decreased significantly with DPA or 1-MCP. Changes in phenolic compounds in pericarp tissues decreased generally during storage, but no significant effect of DPA and 1-MCP treatments on the phenolic compounds was found.

Influence of culture media, pH and temperature on growth and bacteriocin production of bacteriocinogenic lactic acid bacteria

There has been continued interest in bacteriocins research from an applied perspective as bacteriocins have potential to be used as natural preservative. Four bacteriocinogenic lactic acid bacteria (LAB) strains of Lactobacillus curvatus (Arla-10), Enterococcus faecium (JFR-1), Lactobacillus paracasei subsp. paracasei (JFR-5) and Streptococcus thermophilus (TSB-8) were previously isolated and identified in our lab. The objective of this study was to determine the optimal growth conditions for both LAB growth and bacteriocins production. In this study, various growth conditions including culture media (MRS and BHI), initial pH of culture media (4.5, 5.5, 6.2, 7.4 and 8.5), and incubation temperatures (20, 37 and 44 °C) were investigated for LAB growth measured as optical density (OD), bacteriocin activity determined as arbitrary unit and viability of LAB expressed as log CFU ml-1. Growth curves of the bacteriocinogenic LAB were generated using a Bioscreen C. Our results indicated that Arla-10, JFR-1, and JFR-5 strains grew well on both MRS and BHI media at growth temperature tested whereas TSB-8 strain, unable to grow at 20 °C. LAB growth was significantly affected by the initial pH of culture media (p < 0.001) and the optimal pH was found ranging from 6.2 to 8.5. Bacteriocin activity was significantly different in MRS versus BHI (p < 0.001), and the optimal condition for LAB to produce bacteriocins was determined in MRS broth, pH 6.2 at 37 °C. This study provides useful information on potential application of bacteriocinogenic LAB in food fermentation processes.

Proteome changes in banana fruit peel tissue in response to ethylene and high-temperature treatments

Banana (Musa AAA group) is one of the most consumed fruits in the world due to its flavor and nutritional value. As a typical climacteric fruit, banana responds to ethylene treatment, which induces rapid changes of color, flavor (aroma and taste), sweetness and nutritional composition. It has also been reported that ripening bananas at temperatures above 24 °C inhibits chlorophyll breakdown and color formation but increases the rate of senescence. To gain fundamental knowledge about the effects of high temperature and ethylene on banana ripening, a quantitative proteomic study employing multiplex peptide stable isotope dimethyl labeling was conducted. In this study, green (immature) untreated banana fruit were subjected to treatment with 10 μL L(-1) of ethylene for 24 h. After ethylene treatment, treated and untreated fruit were stored at 20 or 30 °C for 24 h. Fruit peel tissues were then sampled after 0 and 1 day of storage, and peel color and chlorophyll fluorescence were evaluated. Quantitative proteomic analysis was conducted on the fruit peels after 1 day of storage. In total, 413 common proteins were identified and quantified from two biological replicates. Among these proteins, 91 changed significantly in response to ethylene and high-temperature treatments. Cluster analysis on these 91 proteins identified 7 groups of changed proteins. Ethylene treatment and storage at 20 °C induced 40 proteins that are correlated with pathogen resistance, cell wall metabolism, ethylene biosynthesis, allergens and ribosomal proteins, and it repressed 36 proteins that are associated with fatty acid and lipid metabolism, redox-oxidative responses, and protein biosynthesis and modification. Ethylene treatment and storage at 30 °C induced 32 proteins, which were mainly similar to those in group 1 but also included 8 proteins in group 3 (identified as chitinase, cinnamyl alcohol dehydrogenase 1, cysteine synthase, villin-2, leucine-transfer RNA ligase, CP47 protein and calmodulin) and repressed 43 proteins in 4 groups (groups 4-7), of which 6 were associated with photosynthesis II oxygen-evolving protein, the photosynthesis I reaction center, sugar metabolism, the redox-oxidative system and fatty acid metabolism. Differences in the response to ethylene and holding temperature at 30 °C were also revealed and have been discussed. The identities and quantities of the proteins found were linked with quality changes. This study demonstrates that ethylene and high temperature influence banana fruit ripening and senescence at the proteomic level and reveals the mechanisms by which high temperature accelerates banana fruit ripening.

Ethylene and 1-MCP regulate major volatile biosynthetic pathways in apple fruit

The effects of ethylene and 1-methylcyclopropene (1-MCP) on apple fruit volatile biosynthesis and gene expression were investigated. Statistical analysis identified 17 genes that changed significantly in response to ethylene and 1-MCP treatments. Genes encoding branched-chain amino acid aminotransferase (BCAT), aromatic amino acid aminotransferase (ArAT) and amino acid decarboxylases (AADC) were up-regulated during ripening and further enhanced by ethylene treatment. Genes related to fatty acid synthesis and metabolism, including acyl-carrier-proteins (ACPs), malonyl-CoA:ACP transacylase (MCAT), acyl-ACP-desaturase (ACPD), lipoxygenase (LOX), hydroperoxide lyase (HPL), alcohol dehydrogenase (ADH), pyruvate decarboxylase (PDC2), β-oxidation, acyl-CoA synthetase (ACS), enoyl-CoA hydratase (ECHD), acyl-CoA dehydrogenase (ACAD), and alcohol acyltransferases (AATs) also increased during ripening and in response to ethylene treatment. Allene oxide synthase (AOS), alcohol dehydrogenase 1 (ADH1), 3-ketoacyl-CoA thiolase and branched-chain amino acid aminotransferase 2 (BCAT2) decreased in ethylene-treated fruit. Treatment with 1-MCP and ethylene generally produced opposite effects on related genes, which provides evidence that regulation of these genes is ethylene dependent.

Targeted quantitative proteomic investigation employing multiple reaction monitoring on quantitative changes in proteins that regulate volatile biosynthesis of strawberry fruit at different ripening stages

A targeted quantitative proteomic investigation employing the multiple reaction monitoring (MRM, SRM) technique was conducted on strawberry fruit at different development stages. We investigated 22 proteins and isoforms from 32 peptides with 111 peptide transitions, which may be involved in the volatile aroma biosynthesis pathway. The normalized protein abundance was significantly changed in coincidence with increased volatile production and advanced fruit maturities. Among them, alcohol acyltransferase (AAT), quinone oxidoreductase (QR), malonyl Co-A decarboxylase, (MLYCD), pyruvate decarboxylase (PDC), acetyl Co-A carboxylase (ACCase), and acyl Co-A synthetase (ACAs) were increased significantly. Several alcohol dehydrogenases (ADHs), and 3-oxoacyl-ACP synthase were significantly decreased. Furthermore, the expression of seven genes related to strawberry volatile production was also investigated using real-time qPCR. Among the tested genes, QR, AAT, ACCase, OMT, PDC and ADH showed increased up-regulation during fruit ripening, while 3-isopropylmalate dehydrogenase (IMD) decreased. Strong correlation between quantitative proteomic data and gene expression suggested that AAT, QR, ACCase, and PDC played critical roles in volatile biosynthesis of strawberry during fruit ripening. Poor correlation between protein abundance and gene expression of ADH was found.

Interaction between feed management systems and omega-3 fatty acid supplementation on bovine immunization parameters (VET1P.1116)

A trial was designed to investigate impacts of omega-3 fatty acid feeding regimes on bovine immunization responses. Dietary supplements contained either fish oil or microalgae as omega-3 fatty acid sources, and cattle were divided into 2 feed management systems; they either grazed pasture or were kept in barn tie stalls and fed total mixed rations (TMR). Cattle were immunized with keyhole limpet hemocyanin (KLH), a standard T cell dependent antigen. Dietary supplements and feeding systems influenced the response of cattle to immunization with KLH. Anti-KLH IgM, IgG and IgA antibody levels in serum were significantly higher in cattle grazing pasture than those fed TMR. Cattle consuming microalgae had consistently higher anti-KLH IgG2 and IgM antibody levels compared to cattle fed fish oil. Effects of omega-3 fatty acid supplements and TMR versus pasture-based diets were also apparent in cytokine profiles from spleen and cecal tissues. Levels of transforming growth factor-beta (TGF-β) were highest in cecal tissue of pasture-grazing cattle (P &lt; 0.0001), and spleen TGF-β levels were highest in pasture-grazing cattle consuming microalgae (P = 0.0073).These findings suggest that effects of omega-3 supplements on bovine immunity are influenced by the feed management system, with heightened effects on antibody production observed with a pasture system relative to a confinement and TMR-based diet.

Antimicrobial activity of bacteriocin-producing lactic acid bacteria isolated from cheeses and yogurts

The biopreservation of foods using bacteriocinogenic lactic acid bacteria (LAB) isolated directly from foods is an innovative approach. The objectives of this study were to isolate and identify bacteriocinogenic LAB from various cheeses and yogurts and evaluate their antimicrobial effects on selected spoilage and pathogenic microorganisms in vitro as well as on a food commodity.

LAB were isolated using MRS and M17 media. The agar diffusion bioassay was used to screen for bacteriocin or bacteriocin-like substances (BLS) producing LAB using Lactobacillus sakei and Listeria innocua as indicator organisms. Out of 138 LAB isolates, 28 were found to inhibit these bacteria and were identified as strains of Enterococcus faecium, Streptococcus thermophilus, Lactobacillus casei and Lactobacillus sakei subsp. sakei using 16S rRNA gene sequencing. Eight isolates were tested for antimicrobial activity at 5°C and 20°C against L. innocua, Escherichia coli, Bacillus cereus, Pseudomonas fluorescens, Erwinia carotovora, and Leuconostoc mesenteroides subsp. mesenteroides using the agar diffusion bioassay, and also against Penicillium expansum, Botrytis cinerea and Monilinia frucitcola using the microdilution plate method. The effect of selected LAB strains on L. innocua inoculated onto fresh-cut onions was also investigated.

Twenty percent of our isolates produced BLS inhibiting the growth of L. innocua and/or Lact. sakei. Organic acids and/or H₂O₂ produced by LAB and not the BLS had strong antimicrobial effects on all microorganisms tested with the exception of E. coli. Ent. faecium, Strep. thermophilus and Lact. casei effectively inhibited the growth of natural microflora and L. innocua inoculated onto fresh-cut onions. Bacteriocinogenic LAB present in cheeses and yogurts may have potential to be used as biopreservatives in foods.

Antimicrobial effects of a commercial fermentation product on fresh-cut onions

The antimicrobial effects of a commercial fermentation product (CFP) added to fresh-cut onions was assessed. Diced onions without treatment were packed in sealed and vented single-pinhole polyethylene bags, which served as controls. Treated and control samples were then stored at 4 and 7°C. Changes in the microbial loads including total aerobic bacteria, yeasts and molds, and coliforms were determined. Quality parameters including O(2)-CO(2) concentration, pH, soluble solids, and conductivity were also evaluated following 0, 3, 7, 10, 14, and 18 days of storage. After 10 days of storage at 4°C, CFP-treated samples had significantly lower microbial loads (P < 0.001), and aerobic plate counts, yeast and mold counts, and coliform counts were lower by 2.5, 3.2, and 1.4 log, respectively, compared with the controls. The addition of 0.5 or 1% CFP maintained the shelf life of fresh-cut onions for up to 14 and 18 days, respectively, compared with 10 days for the control. In addition, it was determined that storage temperature played an important role in maintaining the quality of fresh-cut onions. Significant (P ≤ 0.05) differences in microbial loads and product quality were found between 4 and 7°C in all treatments.

Effects of dietary algal supplementation on bovine immunity (39.50)

Marine algae are primary producers of long chain omega-3 fatty acids and can serve as novel dairy feed supplements with the added potential to influence bovine immunity. Our objective was to assess the immunomodulatory impact of dietary supplementation with different algal types (macroalgae and microalgae). Effects of dietary algal supplementation were examined using a crossover design and a 28 day feeding period with each algal type. Primary immunization with Keyhole Limpet Hemocyanin (KLH) was carried out 8 days into the trial, with secondary immunization 14 days later. KLH-specific serum IgG responses were significantly higher in cows receiving macroalgae-supplemented feed than in cows receiving microalgae-supplemented feed. In contrast, cows receiving microalgae-supplemented feed showed significantly higher levels of macrophage oxidative burst activity in response to PMA challenge in vitro. These results suggest that dietary supplementation with algal products has immunomodulatory potential and also indicates that the effects on cellular and humoral immunity are dependent on the type of algae used.

Funded by the Atlantic Innovation Fund.

Objective haemodynamic assessment after acute myocardial infarction

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Haemodynamic effects of morphine in patients with acute myocardial infarction

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