Lower Viable Counts Research Articles

Use of Lactoperoxidase Inhibitory Effects to Extend the Shelf Life of Meat and Meat Products.

Lactoperoxidase (LP) is an important enzyme of the salivary and mammary glands. It has been proven to increase the shelf life of raw milk by inhibiting the growth of bacteria, especially Listeria monocytogenes, Escherichia coli, Staphylococcus aureus, and Pseudomonas spp. The aim of this work was to verify the use of LP to extend the shelf life of meat products. In vitro experiments showed inhibitory effects on the selected bacteria (Listeria innocua (ATCC 33090), Staphylococcus saprophyticus (CP054440.1), and Pseudomonas fluorescens (ATCC 13525) due to a prolongation of the lag phase of growth curves. A lower increase in viable counts (p < 0.05) was also found by testing pork cubes' surface treated with LP solution (5%) + L. innocua and stored for 7 days at 15 °C. LP has also been studied at concentrations of 0.25 and 0.50% in meat products (pork ham and pâté) during refrigerated storage (4 °C for 28 days). Lower viable counts were observed throughout the storage experiment, especially for 0.50% LP (p < 0.05). Meat products containing LP also showed lower levels of oxidation (MAD) (p < 0.05). According to these results, LP could extend the shelf life of a wider range of products.

Abstract 9 Identification of Effective Changes to Workflow Triaging Criteria and Production Planning

Abstract Introduction The Cleveland Cord Blood Center (CCBC) analyzes fresh incoming cord blood units for the total nucleated cell (TNC) count. Units that meet the TNC criteria are processed for clinical banking and units not meeting the defined criteria are made available for research collaborations. CCBC sought to understand if adding additional pre-screening criteria would reduce post-manufacturing deferral rates and increase production of licensed units. Objectives To identify the main failure modes resulting in cord blood unit deferral for clinical banking post-manufacturing. To identify key factors resulting in unlicensed status of processed cord blood units. To implement changes to pre-screening strategies to reduce deferral rates and increase production of licensed units. Methods CCBC created four cross-departmental teams to evaluate the main reasons for deferrals post-manufacturing and to evaluate travel-risk history. Each committee had representation from collections, quality, and laboratory staff. Data was evaluated that was collected between January and June 2022. Results The committees identified that 19% of all deferrals post-manufacturing were related to low CD34 count and/or viability and that 17% of all processed units were unlicensed due to travel to Zika related areas. In March 2023, pre-screening criteria was updated to include a pre-processed CD34 count and viability and a pre-screening of the donating mother for travel history after consenting and prior to manufacturing. Units that fulfilled both the TNC and CD34 cut offs and did not have a high-risk travel history were processed for clinical banking. Data evaluated from March and April 2023 indicated that the deferral rates for low viable CD34 counts post-manufacturing went from 19% down to 0% and the percentage of high-risk travel units manufactured was reduced from 17% to 7%. Discussion Review of failure modes identified two main factors to guide improved triage efficiency. By implementing a pre-processing CD34 count, the larger TNC and CD34 cord blood units were identified for banking for clinical use. By using a pre-screening process at collection sites, high-risk travel donations were identified prior to processing. In the two-month timeframe evaluated, the overall deferral rates were reduced by roughly 7% and post-manufacturing licensure status increased from 83% to 93%.

Antibacterial Effect of Melanoidins Derived From Xylose and Phenylalanine Against Bacillus cereus and Clostridium perfringens

Melanoidins produced from the combination of D-xylose and L-phenylalanine have been reported to exhibit strong antibacterial effects. This study investigated the influence of environmental factors, such as temperatures (10, 15, 20, 25, 30, 35, 40, and 45°C), pH (5.5, 6.0, 6.5, 7.0, 7.5, and 8.0), and water activity (aw: 0.99, 0.96, and 0.93), on the antibacterial effect of the melanoidins produced from the combination of D-xylose with L-phenylalanine against Bacillus cereus and Clostridium perfringens in culture media. Furthermore, freeze-dried powdered melanoidin was used to determine the minimum concentration for growth inhibition, to compare the antibacterial effect of the melanoidin with conventional food preservatives. The liquid melanoidins significantly inhibited the growth of B. cereus (up to 4 log CFU/mL at the maximum) and C. perfringens (up to 6.5 log CFU/mL at the maximum) regardless of the incubation temperatures. However, the remarkable difference between the presence and absence of the melanoidins was demonstrated in the range of 20–35°C as 4 log-cycle lower in B. cereus and 2 log-cycle lower in C. perfringens than those without the melanoidins. The antibacterial effect of the melanoidin on B. cereus was not influenced by pH from 5.5 to 7.0, which exhibited 2–3 log-cycle lower viable counts than those without the melanoidin. Only one log-cycle difference between with and without the melanoidin was shown in C. perfringens growth under the pH range of 5.5–7.0. Although there was no significant difference in the growth of B. cereus between three aw conditions, the melanoidin exhibited a significant antibacterial effect at aw 0.99 demonstrating 4 log-cycle lower viable numbers than those without the melanoidin. Minimum inhibitory concentration of the melanoidin powder for B. cereus and C. perfringens was 7 mg/mL and 15 mg/mL, respectively, regardless of the kind of foods. Furthermore, the melanoidin exhibited comparable antibacterial effect on B. cereus and C. perfringens to potassium sorbate and sodium benzoate under the same concentration as the minimum inhibitory concentration of the melanoidin, demonstrating 2 log-cycle reduction during 3 days of incubation period at 25°C. The results presented here suggest that the xylose- and phenylalanine-based melanoidin demonstrates the possibility to be an alternative food preservative.

Improved Loading Capacity and Viability of Probiotics Encapsulated in Alginate Hydrogel Beads by In Situ Cultivation Method.

The objective of this research was to encapsulate probiotics by alginate hydrogel beads based on an in situ cultivation method and investigate the influences on the cell loading capacity, surface and internal structure of hydrogel beads and in vitro gastrointestinal digestion property of cells. Hydrogel beads were prepared by extrusion and cultured in MRS broth to allow probiotics to grow inside. Up to 10.34 ± 0.02 Log CFU/g of viable cell concentration was obtained after 24 h of in situ cultivation, which broke through the bottleneck of low viable cell counts in the traditional extrusion method. Morphology and rheological analyses showed that the structure of the eventually formed probiotic hydrogel beads can be loosed by the existence of hydrogen bond interaction with water molecules and the internal growth of probiotic microcolonies, while it can be tightened by the acids metabolized by the probiotic bacteria during cultivation. In vitro gastrointestinal digestion analysis showed that great improvement with only 1.09 Log CFU/g of loss in viable cells was found after the entire 6 h of digestion. In conclusion, the current study demonstrated that probiotic microcapsules fabricated by in situ cultivation method have the advantages of both high loading capacity of encapsulated viable cells and good protection during gastrointestinal digestion.

Enzymatic Activity and Horizontal Gene Transfer of Heavy Metals and Antibiotic Resistant Proteus vulgaris from Hospital Wastewater: An Insight.

Globally, the issue of microbial resistance to medicines and heavy metals is getting worse. There are few reports or data available for Proteus vulgaris (P. vulgaris), particularly in India. This investigation intends to reveal the bacteria's ability to transmit genes and their level of resistance as well. The wastewater samples were taken from several hospitals in Lucknow City, India, and examined for the presence of Gram-negative bacteria that were resistant to antibiotics and heavy metals. The microbial population count in different hospital wastewaters decreases with increasing concentrations of metal and antibiotics. Among all the examined metals, Ni and Zn had the highest viable counts, whereas Hg, Cd, and Co had the lowest viable counts. Penicillin, ampicillin, and amoxicillin, among the antibiotics, demonstrated higher viable counts, whereas tetracycline and erythromycin exhibited lower viable counts. The MIC values for the P. vulgaris isolates tested ranged from 50 to 16,00 μg/ml for each metal tested. The multiple metal resistance (MMR) index, which ranged from 0.04 to 0.50, showed diverse heavy metal resistance patterns in all P. vulgaris isolates (in the case of 2-7 metals in various combinations). All of the tested isolates had methicillin resistance, whereas the least number of isolates had ofloxacin, gentamycin, or neomycin resistance. The P. vulgaris isolates displayed multidrug resistance patterns (2-12 drugs) in various antibiotic combinations. The MAR indexes were shown to be between (0.02-0.7). From the total isolates, 98%, 84%, and 80% had urease, gelatinase, and amylase activity, whereas 68% and 56% displayed protease and beta-lactamase activity. Plasmids were present in all the selected resistant isolates and varied in size from 42.5 to 57.0 kb and molecular weight from 27.2 to 37.0 MD. The transmission of the antibiotic/metal resistance genes was evaluated between a total of 7 pairs of isolates. A higher transfer frequency (4.4 × 10-1) was observed among antibiotics, although a lower transfer frequency (1.0 × 10-2) was observed against metals in both the media from the entire site tested. According to exponential decay, the population of hospital wastewater declined in the following order across all sites: Site II > Site IV > Site III > Site I for antibiotics and site IV > site II > site I >site III for metal. Different metal and antibiotic concentrations have varying effects on the population. The metal-tolerant P. vulgaris from hospital wastewater was studied in the current study had multiple distinct patterns of antibiotic resistance. It could provide cutting-edge methods for treating infectious diseases, which are essential for managing and assessing the risks associated with hospital wastewater, especially in the case of P. vulgaris.

Effect of High Hydrostatic Pressure on the Metabolite Profile of Striped Prawn (Melicertus kerathurus) during Chilled Storage.

A variety of metabolites contribute to the freshness and taste characteristics of seafood. This study investigated the effects of high hydrostatic pressure (HHP; 400, 500, and 600 MPa) for 10 min) on the metabolome of striped prawn during chilled storage, in relation to microorganisms' development. All treated samples showed lower viable counts throughout storage compared to the untreated counterparts. The limit of acceptability from a microbiological point of view was extended from 9 to as many as 35 days by 600 MPa treatment. Metabolites were quantified by 1H-NMR through a targeted-untargeted metabolomic approach. Molecules linked to nucleotides' degradation and amines' anabolism suggested an overall freshness improvement granted by HHP. Notably, putrescine and cadaverine were detected only in untreated prawn samples, suggesting the inactivation of degradative enzymes by HHP. The concentration of molecules that influence umami perception was significantly elevated by HHP, while in untreated samples, the concentration of molecules contributing to a sour taste gradually increased during storage. As metabolomics was applied in its untargeted form, it allowed us to follow the overall set of metabolites related to HHP processing and storage, thus providing novel insights into the freshness and taste quality of striped prawn as affected by high hydrostatic pressure.

Co‐extrusion and extrusion microencapsulation: Effect on microencapsulation efficiency, survivability through gastrointestinal digestion and storage

AbstractProbiotic is a functional food ingredient that is commonly used in the manufacturing of fermented dairy products and vegetable‐based foods. The consumption of probiotics has been claimed to confer health benefits to the host. However, probiotic cells are sensitive to harsh environments such as extreme pH and enzymes in the gastrointestinal tract. Hence, the microencapsulation technique is often adopted to shield probiotics from the outer environment. This review introduces a more advanced extrusion technique called co‐extrusion, which has been used to microencapsulate probiotics over the last few years. Both co‐extrusion technique and extrusion technique in microencapsulating probiotics were discussed extensively in this article. Furthermore, the impact of encapsulating probiotics in contrast with unencapsulated cells was also presented. This review highlighted some of the factors that might cause low viable cell count during microencapsulation and large microbead size. Lastly, the survivability of encapsulated probiotics in gastrointestinal digestion and storage under different temperatures were evaluated and the importance of probiotic microencapsulation was also emphasized.Practical ApplicationsThe detailed information on extrusion and co‐extrusion techniques for probiotics microencapsulation is presented in this review. This information is useful for researchers and industrialists in understanding and applying both encapsulation techniques on probiotics for different purposes. Through this paper, the readers would also gain more insight into the factors affecting the viability and microbead size of the encapsulated probiotic to further optimize the extrusion and co‐extrusion encapsulation process. Furthermore, the ideal storage temperature and additional drying process for the encapsulated probiotic identified in this review would open opportunities for industrialists to produce functional probiotic products with a high viable cell count.

Effect of Novel Bacteriocinogenic Lactobacillus fermentum BZ532 on Microbiological Shelf-Life and Physicochemical and Organoleptic Properties of Fresh Home-Made Bozai.

Bacteriocinogenic Lactobacillus fermentum BZ532 with novel bacteriocin LF-BZ532 was originally isolated from Chinese cereal fermented drink, showing an antimicrobial characteristic during fermentation. This study aimed to explore the in situ antimicrobial activities of L. fermentum BZ532 and co-culturing investigation against key food pathogens, i.e., Staphylococcus aureus and Escherichia coli K-12, was conducted during fresh bozai production. The growth of spoilage bacteria was suppressed and bacterial count was reduced to a significantly low level during 48 h of co-cultures. In situ production of antimicrobial compounds expressed positive activity against S. aureus and E. coli K-12, but negative acitivity against Salmonella sp. D104. The total viable count of bozai BZ-Lf (bozai fermented with BZ532 strain) had a comparatively lower viable count than bozai BZ-C (bozai as an experimental control without BZ532) during storage of 7 days. Titratable acidity of bozai treatments (BZ-C, BZ-Lf) was increased, while pH declined accordingly during storage of 7 days. The organoleptic quality of bozai BZ-C had low sensorial scores as compared with BZ-Lf during storage. In comparison with naturally fermented bozai (BZ-C), L. fermentum BZ532 (BZ-Lf) could significantly reduce the microbial spoilage and extend the shelf-life based on microbiological examination. Conclusively, L. fermentum BZ532 can be used as a bio-protective culture for improving the safety of bozai.

Effect of Temperature at the Shelf Life of Yogurt and the Role of &amp;lt;i&amp;gt;Listeria monocytogenes&amp;lt;/i&amp;gt; and &amp;lt;i&amp;gt;E. coli&amp;lt;/i&amp;gt; Inoculated in Unflavoured and Flavoured Yogurts

<i>E. coli</i> and <i>L. monocytogenes</i> are all dairy product related pathogens. The presence of these pathogens can lead to contamination. To increase the shelf life of yogurt we have to monitor the temperature at which it is stored, the change in microbial counts, pH, acidity, sensory attributes and percentage of free whey. Adaptation Test Acid demonstrates that the microorganisms such as Salmonella spp., <i>E. coli</i>, and L. monocytogenes are frequently identified to have a higher survival rate in meals when compared with non-adopted ones. When they are exposed to unfavorable growth circumstances such as severely acidic environments. In this study, we evaluated the survival of wild and adapted L. monocytogenes strains, inoculated at the same concentration around 4 log cfu/g; a slow decrease in the loads was observed until d 28 in unflavored inoculated with the wild strain. Three different experiments are performed on yogurt to evaluate the difference between flavored and unflavored yogurt, shelf life of them at different temperatures and to determine the role of <i>E. coli</i> and <i>Listeria monocytogenes</i> and see what changes it brings to the composition of yogurt. First trial is performed at three different temperatures. These are at 4, 8 and 20°C. Both flavored and unflavored yogurt sample showed low viable counts at 4°C until the end of trial. While performing this trial at 4°C the loads are lower in strawberry yogurts as compared to that of unflavored yogurt because potassium sorbate is present in fruit pure and anti-microbial activity is exerted by that. In second trial, <i>E. coli</i> and <i>Listeria monocytogenes</i> are added to the yogurt sample at two concentrations which 2 and 5 log cfu/g which will show a rapid decrease in acidic conditions in both flavored and unflavored yogurt samples. <i>Listeria monocytogenes</i> is very resistant in this case and presence of it can always be seen until the end period. In the third trial, the adaption of the yogurt sample is monitored after the inoculation of microorganisms in it. Between the wild acid adapted strains of <i>L. monocytogenes</i> no statistically significant difference is detected and that must be because to the quick adaption after the inoculation. Pasteurization is one of the main processes which are used to make the dairy products pathogen free and the basic functioning of it is through temperature and discussed in the paper.

Transmission of bacteria in bronchiectasis and chronic obstructive pulmonary disease: Low burden of cough aerosols.

Aerosol transmission of Pseudomonas aeruginosa has been suggested as a possible mode of respiratory infection spread in patients with cystic fibrosis (CF); however, whether this occurs in other suppurative lung diseases is unknown. Therefore, we aimed to determine if (i) patients with bronchiectasis (unrelated to CF) or chronic obstructive pulmonary disease (COPD) can aerosolize P. aeruginosa during coughing and (ii) if genetically indistinguishable (shared) P. aeruginosa strains are present in these disease cohorts. People with bronchiectasis or COPD and P. aeruginosa respiratory infection were recruited for two studies. Aerosol study: Participants (n = 20) underwent cough testing using validated cough rigs to determine the survival of P. aeruginosa aerosols in the air over distance and duration. Genotyping study: P. aeruginosa sputum isolates (n = 95) were genotyped using the iPLEX20SNP platform, with a subset subjected to the enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR) assay to ascertain their genetic relatedness. Aerosol study: Overall, 7 of 20 (35%) participants released P. aeruginosa cough aerosols during at least one of the cough aerosol tests. These cough aerosols remained viable for 4 m from the source and for 15 min after coughing. The mean total aerosol count of P. aeruginosa at 2 m was two colony-forming units. Typing study: No shared P. aeruginosa strains were identified. Low viable count of P. aeruginosa cough aerosols and a lack of shared P. aeruginosa strains observed suggest that aerosol transmission of P. aeruginosa is an unlikely mode of respiratory infection spread in patients with bronchiectasis and COPD.

Viability of free and encapsulated Lactobacillus acidophilus incorporated to cassava starch edible films and its application to Manaba fresh white cheese

Lactic acid bacteria (LAB) confer health benefits to the host. However, studies showed that LAB are sensitive to adverse environmental conditions. Therefore, encapsulation may be used to protect LAB against hard environmental conditions. Manaba fresh white cheese (Manaba cheese) is an Ecuadorian artisanal cheese that does not fulfill regulations, leading to the presence of microorganism like Salmonella spp. The present work studies the viability of free and encapsulated L. acidophilus at 25 °C. Microbiological analyses were performed on Manaba cheese coated with starch containing either free or encapsulated L. acidophilus during storage at 4 °C. Results showed that encapsulated L. acidophilus had higher survival than free cells during storage at 25 °C. Both coated cheese samples containing either free or encapsulated cells had lower viable counts than uncoated samples along the storage time at 4 °C.

Role of Phage Shock Protein in Recovery of Heat-injured Salmonella.

Sublethally heat-injured cells of Salmonella in food can recover under favorable conditions, leading to foodborne illness. To elucidate the molecular mechanism of recovery from heat injury, the global changes in gene transcription of Salmonella Typhimurium were investigated in previous study. In this study, the functions of genes involved in phage shock response (viz., phage shock protein (psp) genes), the transcription levels of which were found in previous study to be increased during recovery from heat injury, were investigated in recovering cells. The increase in pspABCDEFG transcription levels during the recovery process was confirmed by qRT-PCR. To understand the role of psp genes in heat injury recovery, a pspA deletion mutant (ΔpspA) and a pspA-overexpressing strain (S. Typhimurium pBAD30/pspA (+) ) were constructed. ΔpspA showed slightly lower viable counts and membrane potential than those of the wild-type strain during recovery. On the other hand, there was no significant difference in the viable counts between S. Typhimurium pBAD30/pspA (+) and the control strains S. Typhimurium pBAD30/pspA (-) and S. Typhimurium pBAD30 (+) during recovery. It would seem that a lack of PspA protein alone somewhat affects the recovery of S. Typhimurium from heat injury, but overexpression of PspA alone is not sufficient to overcome this effect.

Influence of Processing Parameters on Microbial Load, Sensory Acceptability, and Mineral Contents of Dehydrated Catfish (Clarias gariepinus)

ABSTRACTCatfish was dehydrated to improve handling using Response Surface Methodology for experimental design. Brine concentration (%), brining time (min) and drying temperature (°C) as processing parameters interacted in different combinations. Influence of processing parameters on microbial load, sensory acceptability and mineral contents of dehydrated catfish was investigated. Data analysed using regression, ANOVA and average ranking grade. Low total viable and fungi counts (ranged 1.0x103-3.0x103 CFU/g) with no detection of pathogen indicates safety for consumption. Brine concentration significantly (p < 0.05) influenced the texture of catfish. The model accounted for only 29.36% of the total variation (R2 = 0.2936). The 6% brine, 90 min and 110°C treatment, significantly improved the overall-acceptability. Calcium content (ranged 19.60–52.60 mg/100 g) was significantly higher which could improve the nutrient intake to facilitate development and maintenance of strong bones. Knowledge about safety, acceptability and nutrient content of dehydrated catfish could contribute positively to reshaping decision-making about catfish consumption.

Metal tolerance analysis of Gram negative bacteria from hospital effluents of Northern India

Effluents from different hospitals were analyzed to Nickel, Chromium, Cobalt, Copper, Mercury, Cadmium and Zinc resistance among Gram negative bacteria. The resistance among the Gram negative bacterial population varied considerably in different metal and water sampling sites. Gram negative bacteria showed lower metal resistant viable count range 4.01 x104-1.3 x103 at 50-100 μg/ml in site-IV as compared to 11.03x105-1.03x104, 12.02x105-1.4x103 and 12.33x105-2.7x103 in site-I, II and III against all metal tested, respectively. Viable counts of Gram negative bacterial population were recorded higher against Nickel and Zinc from sampling site-III as compared to other sites tested. Lower viable counts of Gram negative bacteria were recorded against Mercury in all sites tested. All the isolates of Gram negative bacteria showed their tolerance level (Minimum inhibitory concentration) in the range of 50-1600μg/ml against all the metal tested. Of 88%, 76% and 86% isolates exhibited their MIC at 50-100 μg/ml against Mercury, Cadmium and Cobalt in all the sites tested, respectively. Maximum 60% and 32% of the isolates demonstrated their MIC at 1200-1600 μg/ml against Cr2+ and Cu2+ from the entire site tested, respectively. All Gram negative bacterial isolates also observed multiple resistance patterns (2-7 metal) in different combination of metals. The Multi metal resistance Index (MMR) index ranges were found (0.03-0.71) indicating the high risk of environmental contamination and emergence of metal resistance which may promote the development of resistance to antibiotics among the pathogens.

Survival and bioactivities of selected probiotic lactobacilli in yogurt fermentation and cold storage: New insights for developing a bi-functional dairy food

In previous work, we demonstrated that two probiotic strains, namely Lactobacillus casei PRA205 and Lactobacillus rhamnosus PRA331, produce fermented milks with potent angiotensin-converting enzyme (ACE)-inhibitory and antioxidant activities. Here, we tested these strains for the survivability and the release of antihypertensive and antioxidant peptides in yogurt fermentation and cold storage. For these purposes three yogurt batches were compared: one prepared using yogurt starters alone (Lactobacillus delbrueckii subspecies bulgaricus 1932 and Streptococcus thermophilus 99), and the remaining two containing either PRA205 or PRA331 in addition to yogurt starters. Despite the lower viable counts at the fermentation end compared to PRA331, PRA205 overcame PRA331 in survivability during refrigerated storage for 28 days, leading to viable counts (>108 CFU/g) higher than the minimum therapeutic threshold (106 CFU/g). Analyses of in vitro ACE-inhibitory and antioxidant activities of peptide fractions revealed that yogurt supplemented with PRA205 displays higher amounts of antihypertensive and antioxidant peptides than that produced with PRA331 at the end of fermentation and over storage. Two ACE-inhibitory peptides, Valine-Proline-Proline (VPP) and Isoleucine-Proline-Proline (IPP), were identified and quantified. This study demonstrated that L. casei PRA205 could be used as adjunct culture for producing bi-functional yogurt enriched in bioactive peptides and in viable cells, which bring health benefits to the host as probiotics.

Cultivation of Staphylococcus epidermidis in the Human Spaceflight Environment Leads to Alterations in the Frequency and Spectrum of Spontaneous Rifampicin-Resistance Mutations in the rpoB Gene.

Bacteria of the genus Staphylococcus are persistent inhabitants of human spaceflight habitats and represent potential opportunistic pathogens. The effect of the human spaceflight environment on the growth and the frequency of mutations to antibiotic resistance in the model organism Staphylococcus epidermidis strain ATCC12228 was investigated. Six cultures of the test organism were cultivated in biological research in canisters–Petri dish fixation units for 122 h on orbit in the International Space Station (ISS) as part of the SpaceX-3 resupply mission. Asynchronous ground controls (GCs) consisted of identical sets of cultures cultivated for 122 h in the ISS Environmental Simulator at Kennedy Space Center. S. epidermidis exhibited significantly lower viable counts but significantly higher frequencies of mutation to rifampicin (Rif) resistance in space vs. GC cultures. The spectrum of mutations in the rpoB gene leading to RifR was altered in S. epidermidis isolates cultivated in the ISS compared to GCs. The results suggest that the human spaceflight environment induces unique physiologic stresses on growing bacterial cells leading to changes in mutagenic potential.

Bacillus thermoamylovorans Spores with Very-High-Level Heat Resistance Germinate Poorly in Rich Medium despite the Presence of ger Clusters but Efficiently upon Exposure to Calcium-Dipicolinic Acid.

High-level heat resistance of spores of Bacillus thermoamylovorans poses challenges to the food industry, as industrial sterilization processes may not inactivate such spores, resulting in food spoilage upon germination and outgrowth. In this study, the germination and heat resistance properties of spores of four food-spoiling isolates were determined. Flow cytometry counts of spores were much higher than their counts on rich medium (maximum, 5%). Microscopic analysis revealed inefficient nutrient-induced germination of spores of all four isolates despite the presence of most known germination-related genes, including two operons encoding nutrient germinant receptors (GRs), in their genomes. In contrast, exposure to nonnutrient germinant calcium-dipicolinic acid (Ca-DPA) resulted in efficient (50 to 98%) spore germination. All four strains harbored cwlJ and gerQ genes, which are known to be essential for Ca-DPA-induced germination in Bacillus subtilis. When determining spore survival upon heating, low viable counts can be due to spore inactivation and an inability to germinate. To dissect these two phenomena, the recoveries of spores upon heat treatment were determined on plates with and without preexposure to Ca-DPA. The high-level heat resistance of spores as observed in this study (D120°C, 1.9 ± 0.2 and 1.3 ± 0.1 min; z value, 12.2 ± 1.8°C) is in line with survival of sterilization processes in the food industry. The recovery of B. thermoamylovorans spores can be improved via nonnutrient germination, thereby avoiding gross underestimation of their levels in food ingredients.

Effect of high pressure processing and thermal treatment on quality of hilsa (Tenualosa ilisha) fillets during refrigerated storage

Abstract The effect of high pressure processing (250 and 350 MPa for 10 min) and thermal treatment (75 °C for 5 min) on microbiological, physical and biochemical quality of hilsa fillets during refrigeration storage was studied. Thermally treated and the samples at 350 MPa showed higher L* and b* values with lower a* values compared to both control and samples treated at 250 MPa. Trimethylamine nitrogen levels rose over the storage period but did not exceed the critical limit for both pressure and thermally treated samples. High pressure treatments promoted texture improvement and reduced the samples susceptibility to oxidation Pressurization of 350 MPa effectively prevented lipid hydrolysis. The treated samples maintained lower viable counts throughout the storage, thus having better microbial quality than untreated sample. Pressure treatment of 350 MPa was found to be most effective in preserving the quality and extending the shelf life of hilsa fillets for > 25 days compared to 10 days in raw samples. Industrial relevance Hilsa is a high value commodity with persistent demand in seafood market. But it is highly perishable with limited shelf life. High pressure processed hilsa fillets showed better quality attributes (texture, FFA, lipid oxidation) and extended shelf life compared to thermal treatment. Thus, high pressure processing is potentially more suitable processing method than thermal treatment.

Antimicrobial resistant coliform bacteria in the Gomti river water and determination of their tolerance level.

The distribution of resistance to ampicillin, chloramphenicol, sulfonamides, tetracycline, and streptomycin among coliform in the Gomti river water samples was investigated. The coliform populations were isolated on Mac Conky and eosin methylene blue (EMB) agar plates supplemented with antibiotics. The incidence of resistance among the coliform population varied considerably in different drug and water sampling sites. Coliform bacteria showed lower drug resistant viable count in sampling site-III (receiving treated wastewater) as compared to more polluted site-I and site-II. Viable count of coliform population obtained on both medium was recorded higher against erythromycin from sampling site-III. Lower viable count of coliforms was recorded against tetracycline in site-II and III. Similar resistance pattern was obtained in the frequency of E. coli and Enterobacter species from all the three sampling sites. Percentage of antibiotic resistant E. coli was observed higher than Enterobacter spp among the total coliforms against all antibiotics tested without Erythromycin and penicillin in site-I and II respectively. Isolates of E. coli and Enterobacter spp. showed their tolerance level (MIC) in the range of 2-100 against the antibiotics tested. Maximum number of isolates of both genus exhibited their MICs at lower concentration range 2-5µg/ml against ciprofloxacin, tetracyclin and amoxycillin.AbbreviationsEMB - Eosin methylene blue, IMViC tests - Indole, Methyl Red, Voges Proskauer and Citrate Utilization Tests, MIC - Minimum inhibitory concentration.

Effect of a probiotic mixture on intestinal microflora, morphology, and barrier integrity of broilers subjected to heat stress

The current study investigated the efficacy of a probiotic mixture on ameliorating heat stress-induced impairment of intestinal microflora, morphology, and barrier integrity in broilers. The probiotic mixture contained Bacillus licheniformis, Bacillus subtilis, and Lactobacillus plantarum. Three hundred sixty 21-d-old Ross 308 male broilers were allocated in 4 experimental treatments, each of which was replicated 6 times with 15 broilers per replicate. A 2 × 2 factorial design was used in the study, and the main factors were composed of diet (basal diet or addition of 1.5 g/kg of probiotic mixture) and temperature (thermoneutral zone or heat stress). From d 22 to 42, birds were either raised in a thermoneutral zone (22°C) or subjected to cyclic heat stress by exposing them to 33°C for 10 h (from 0800 to 1800) and 22°C from 1800 to 0800. Compared with birds kept in the thermoneutral zone, birds subjected to heat stress had reduced ADG and ADFI; lower viable counts of Lactobacillus and Bifidobacterium and increased viable counts of coliforms and Clostridium in small intestinal contents; shorter jejunal villus height, deeper crypt depth, and lower ratio of villus height to crypt depth; decreased jejunal transepithelial electrical resistance and a higher level of jejunal paracellular permeability of fluorescein isothiocyanate dextran 4 kDa; and downregulated protein levels of occludin and zonula occludens-1 (P < 0.05). Supplemental probiotics increased (P < 0.05) small intestinal Lactobacillus and Bifidobacterium, jejunal villus height, protein level of occludin, and decreased (P < 0.05) feed to gain ratio and small intestinal coliforms. These results indicate that dietary addition of probiotic mixture was effective in partially ameliorating intestinal barrier function. But no temperature × diet interaction was observed in the present study, revealing that the supplemented probiotics had the same effect at both temperatures.