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Journal of Dairy Science Jun 2024Despite good manufacturing practices and rigorous cleaning and sanitizing procedures established in dairy processing plants, microbiological contamination remains the...
Despite good manufacturing practices and rigorous cleaning and sanitizing procedures established in dairy processing plants, microbiological contamination remains the main cause of products being non-compliant and/or atypical and hence not fit for human consumption. The objective of this study was to isolate, identify and characterize bacteria, yeasts and molds associated with substandard dairy products in Canada and to create a collection of reference isolates. In addition to conventional microbiological characterization, each isolate was tested for biofilm-forming ability and susceptibility to heat, antimicrobial agents, and common industrial disinfectants. Among the 105 microbial strains isolated from pasteurized milk, cream, and cheese samples, 24 bacterial isolates, belonging mainly to the genus Pseudomonas, were shown to be moderate or strong biofilm producers in 96-well plates and highly resistant to peracetic acid (100 ppm, 5 min contact time) and sodium hypochlorite (70 ppm, 5 min contact time). In addition, 56 bacterial isolates, including Acinetobacter baumannii, Enterobacter bugandensis, Klebsiella pneumoniae and Pseudomonas spp., were found resistant to ampicillin, fosfomycin and/or ceftriaxone, while 14 others, such as Bacillus spp. and Macrococcus spp., withstood a heat treatment equivalent to low-temperature long-time pasteurization (63°C for 30 min). This descriptive study provides new information on potential problematic microorganisms in dairies and will guide the development of novel control strategies intended to prevent and reduce microbiological contamination and the associated economic losses.
PubMed: 38908709
DOI: 10.3168/jds.2023-24506 -
Veterinary Research Communications Jun 2024Characterization of microbiota structure on the skin of healthy horses is important for further development of modulation strategies to ensure optimal bacterial...
Characterization of microbiota structure on the skin of healthy horses is important for further development of modulation strategies to ensure optimal bacterial composition for physiological processes. This requirement is also supported by the relatively high incidence of dermatological diseases in horses and thus the need to manage them therapeutically. The taxonomic analysis of skin samples (n = 30) from five different body parts of clinically healthy Shetlands ponies females (neck, back, abdomen, pastern, muzzle) kept under homogeneous conditions (in open stalls with paddock, feed with dry hay, green grass ad libitum and granulated feed) was performed using amplification of V3-V4 region of the 16S rRNA gene. Results indicate that bacteria associated with healthy equine skin represent 18 phyla, 29 classes and 119 families. The most abundant phyla were Proteobacteria (30.8 ± 9.1%) followed by Actinobacteriota (20.4 ± 7.6%), Firmicutes (19.5 ± 10.1%), Bacteroidota (8.5 ± 5.0%) and Deinococcota (7.2 ± 14.8%). Among 229 genera identified, Corynebacterium (7.4 ± 6.5%) was the most abundant genus in skin sites of horses, followed by Deinococcus (7.1 ± 14.9%) and Macrococcus (5.0 ± 8.2%). Indices for the richness and diversity of species within bacterial populations for five regions of horses skin revealed no significant variations observed for species richness (Chao1, p-value 0.2001) but significant result for species evenness (Shannon, p-value 0.0049) with maximum on the neck and minimum on the back skin site. The clustering was seen across samples from different skin sites but also across samples collected from individual horses.
PubMed: 38900396
DOI: 10.1007/s11259-024-10444-7 -
Food Chemistry May 2024Reducing nitrites tends to increase the accumulation of hazardous biogenic amines (BAs) in Chinese fermented sausages (CFSs). Gallic acid (GA) has emerged as a potential...
The metabolic regulation mechanism of gallic acid on biogenic amines and nitrosamines in reduced-nitrite Chinese fermented sausages: A perspective of metabolomics and metagenomics.
Reducing nitrites tends to increase the accumulation of hazardous biogenic amines (BAs) in Chinese fermented sausages (CFSs). Gallic acid (GA) has emerged as a potential alternative to reduce nitrite usage and control BAs. This study explored how GA inhibits BAs and nitrosamines accumulation in reduced-nitrite CFSs. Results demonstrated that combining 0.05% (w/w) GA with reduced nitrite effectively curbed BAs and N-nitrosodimethylamine, decreasing total BA from 271.48 to 125.46 mg/kg. Fifty-one metabolites associated with the metabolism of BAs and N-nitrosodimethylamine were identified. GA boosted Lactococcus while reducing spoilage bacteria and Macrococcus. This dual regulation suppressed BAs and dimethylamine accumulation by regulating amino acids and trimethylamine pathways. Consequently, GA achieved an 89.86% reduction in N-nitrosodimethylamine by decreasing the key precursors like putrescine, dimethylamine, and nitrite. These findings offer new insights into utilizing GA and similar plant polyphenols to manage BAs and nitrosamines in meat products with reduced nitrite usage.
PubMed: 38878551
DOI: 10.1016/j.foodchem.2024.139900 -
Foods (Basel, Switzerland) May 2024Dry-aged beef has been long favored by people due to its unique flavor and taste. However, the inner relationship between its overall quality formation and microbial...
Dry-aged beef has been long favored by people due to its unique flavor and taste. However, the inner relationship between its overall quality formation and microbial changes during dry aging has not yet received much attention and research. To deeply reveal the forming mechanism of the unique flavor and taste of dry-aged beef, correlations between its three main quality indicators, i.e., texture, free amino acids (FAAs), volatile flavor compounds (VFCs), and microbial succession were analyzed in this study. The results showed that spp. and spp. were key strains that influenced the total quality of dry-aged beef and strongly correlated with chewiness, hardness, and sweet FAAs (Ala), providing beef with unique palatability and taste. Additionally, among VFCs, spp. and spp. showed a strong correlation with octanal and heptanal, and meanwhile, those highly correlated with nonanal, pentanol, and oct-1-en-3-ol were spp., spp., and spp., respectively, providing beef with a unique flavor. spp. was proposed to be the dominant genus for dry-aged beef. This study provides valuable reference for the understanding of the role of microorganisms involved in dry aging.
PubMed: 38790852
DOI: 10.3390/foods13101552 -
Food Research International (Ottawa,... Jul 2024Single starter can hardly elevate the gel property of fermented freshwater fish sausage. In this work, in order to improve the physical properties of tilapia sausage,...
Novel insight into the formation and improvement mechanism of physical property in fermented tilapia sausage by cooperative fermentation of newly isolated lactic acid bacteria based on microbial contribution.
Single starter can hardly elevate the gel property of fermented freshwater fish sausage. In this work, in order to improve the physical properties of tilapia sausage, two newly isolated strains of lactic acid bacteria (LAB), Latilactobacillus sakei and Pediococcus acidilactici were used for cooperative fermentation of tilapia sausage, followed by the revelation of their formation mechanisms during cooperative fermentation and their improvement mechanisms after comparison with natural fermentation. Both strains, especially L. sakei possessed good growth, acidification ability, and salt tolerance. The gel strength, hardness, springiness, chewiness, whiteness, acidification, and total plate count significantly elevated during cooperative fermentation with starters. Pediococcus, Acinetobacter, and Macrococcus were abundant before fermentation, while Latilactobacillus quickly occupied the dominant position after fermentation for 18-45 h with the relative abundance over 51.5 %. The influence of each genus on the physical properties was calculated through the time-dimension and group-dimension correlation networks. The results suggested that the increase of Latilactobacillus due to the good growth and metabolism of L. sakei contributed the most to the formation and improvement of gel strength, texture properties, color, acidification, and food safety of tilapia sausage after cooperative fermentation. This study provides a novel analysis method to quantitatively evaluate the microbial contribution on the changes of various properties. The cooperative fermentation of LAB can be used for tilapia sausage fermentation to improve its physical properties.
Topics: Fermentation; Animals; Food Microbiology; Tilapia; Fish Products; Hydrogen-Ion Concentration; Latilactobacillus sakei; Lactobacillales; Pediococcus acidilactici; Fermented Foods; Meat Products
PubMed: 38763686
DOI: 10.1016/j.foodres.2024.114456 -
Frontiers in Physiology 2024To investigate the impact of the effect of high temperature stimulation on larvae after a certain period of time, five experimental groups were established at different...
To investigate the impact of the effect of high temperature stimulation on larvae after a certain period of time, five experimental groups were established at different temperatures. Then, the under high temperature stress was fed at 30°C for 70 days. After that, the growth index of the was counted and analyzed. In terms of growth index, high temperature stress had significant effects on FCR, FBW, WGR, and SGR of ( 0.05). The SR increased after being stimulated by temperature ( 0.1). The study revealed that liver cells of were harmed by elevated temperatures of 36°C and 38°C. In the experimental group, the activities of digestive enzymes changed in the same trend, reaching the highest point in the 32°C group and then decreasing, and the AMS activity in the 38°C group was significantly different from that in the 30°C group ( < 0.05). The activities of antioxidase in liver reached the highest at 34°C, which was significantly different from those at 30°C ( < 0.05). In addition, the expression levels of , , , and other genes increased in the experimental group, reaching the highest point at 34°C, and the expression level of the gene reached the highest point at 32°C, which was significantly different from that at 30°C ( < 0.05). However, the expression level of the gene decreased in the experimental group and reached its lowest point at 34°C ( < 0.05). The expression level of the gene increased with the highest temperature stimulus and reached its highest point at 38°C ( < 0.05). In the α diversity index of intestinal microorganisms in the experimental group, the observed species, Shannon, and Chao1 indexes in the 34°C group were the highest ( < 0.05), and β diversity analysis revealed that the intestinal microbial community in the experimental group was separated after high temperature stimulation. At the phylum level, the three dominant flora are , , and . and abundance increased at the genus level, but and abundance decreased. To sum up, appropriate high-temperature stress can enhance the immunity and adaptability of . These results show that the high temperature stimulation of 32°C-34°C is beneficial to the industrial culture of .
PubMed: 38720786
DOI: 10.3389/fphys.2024.1397818 -
PloS One 2024The field of fish microbiome research has rapidly been advancing, primarily focusing on farmed or laboratory fish species rather than natural or marine fish populations....
The field of fish microbiome research has rapidly been advancing, primarily focusing on farmed or laboratory fish species rather than natural or marine fish populations. This study sought to reveal the distinctive gut bacteriome composition and diversity within the anadromous fish species Tenualosa ilisha (hilsa), which holds the status of being the national fish of Bangladesh. We conducted an analysis on 15 gut samples obtained from 15 individual hilsa fishes collected from three primary habitats (e.g., freshwater = 5, brackish water = 5 and marine water = 5) in Bangladesh. The analysis utilized metagenomics based on 16S rRNA gene sequencing targeting the V3-V4 regions. Our comprehensive identification revealed a total of 258 operational taxonomic units (OTUs). The observed OTUs were represented by six phyla, nine classes, 19 orders, 26 families and 40 genera of bacteria. Our analysis unveiled considerable taxonomic differences among the habitats (freshwater, brackish water, and marine water) of hilsa fishes, as denoted by a higher level of shared microbiota (p = 0.007, Kruskal-Wallis test). Among the identified genera in the gut of hilsa fishes, including Vagococcus, Morganella, Enterobacter, Plesiomonas, Shigella, Clostridium, Klebsiella, Serratia, Aeromonas, Macrococcus, Staphylococcus, Proteus, and Hafnia, several are recognized as fish probiotics. Importantly, some bacterial genera such as Sinobaca, Synechococcus, Gemmata, Serinicoccus, Saccharopolyspora, and Paulinella identified in the gut of hilsa identified in this study have not been reported in any aquatic or marine fish species. Significantly, we observed that 67.50% (27/40) of bacterial genera were found to be common among hilsa fishes across all three habitats. Our findings offer compelling evidence for the presence of both exclusive and communal bacteriomes within the gut of hilsa fishes, exhibiting potential probiotic properties. These observations could be crucial for guiding future microbiome investigations in this economically significant fish species.
Topics: Animals; Bangladesh; Gastrointestinal Microbiome; Fishes; RNA, Ribosomal, 16S; Bacteria; Biodiversity; Phylogeny
PubMed: 38691556
DOI: 10.1371/journal.pone.0303047 -
Cellular and Molecular Biology... Apr 2024The existence of diverse microbes in unprocessed camel milk poses a significant threat to the well-being of a large population, especially infants and toddlers. The...
The existence of diverse microbes in unprocessed camel milk poses a significant threat to the well-being of a large population, especially infants and toddlers. The objective of this study was to ascertain the existence of microorganisms in unprocessed raw camel milk by employing a molecular-based technique in combination with a histological examination of bacteria. The identification of microbial species was achieved by employing PCR amplification and sequencing of 16s rRNA gene fragments. Various micorganisms found includes the probiotic Lactobacillus species, Staphylococcus succinic, Macrococcus casealyticus, Bacillus cohnii, and Salinicoccus kunmingensis. To prevent microbial contamination in raw milk, it is necessary to adequately heat or pasteurise the milk and to wash and sterilise the udder before milking the camel. This is because raw milk contains microbes that cause multiple diseases. Moreover, in the current era of the COVID-19 pandemics, ensuring proper sanitary conditions in milk and its derivatives might potentially mitigate the transmission of various diseases among consumers shortly. Keywords: camel, microbiota, 16s rRNA gene, PCR.
Topics: Camelus; Animals; Milk; RNA, Ribosomal, 16S; Microbiota; Polymerase Chain Reaction; Bacteria
PubMed: 38678633
DOI: 10.14715/cmb/2024.70.4.2 -
Biotechnologia 2024The ever-increasing demand for wildlife-derived raw or processed meat commonly known as bushmeat, has been identified as one of the critical factors driving the...
The ever-increasing demand for wildlife-derived raw or processed meat commonly known as bushmeat, has been identified as one of the critical factors driving the emergence of infectious diseases. This study focused on examining the bacterial community composition of smoked and fermented bushmeats, specifically grasscutter, rat, rabbit, and mona monkey. The analysis involved exploring 16Sr RNA amplicon sequences isolated from bushmeat using QIIME2. Microbiome profiles and their correlation with proximate components (PLS regression) were computed in STAMP and XLSTAT, respectively. Results indicate the predominance of (70.9%), (18.58%), and (9.12%) in bushmeat samples at the phylum level. , , , and constituted the core microbiomes in bushmeat samples, ranked in descending order. Notably, significant differences were observed between the bacterial communities of bushmeat obtained from omnivores and herbivores (rat and mona monkey, and grasscutter and mona monkey), as well as those with similar feeding habits (rat and monkey, and grasscutter and rabbit) at the family and genus levels. Each type of bushmeat possessed unique microbial diversity, with some proximate components such as fat in rat samples correlating with , while proteins in Mona monkey correlated with and , respectively. The study underscores public health concerns and highlights probiotic benefits, as bushmeat samples contained both pathogenic and beneficial bacteria. Therefore, future research efforts could focus on improving bushmeat quality.
PubMed: 38633890
DOI: 10.5114/bta.2024.135637 -
Food Chemistry Aug 2024Single starter can hardly improve the volatile flavor of fermented fish surimi. In this study, the changes of volatile compounds (VCs) and microbial composition during...
Improvement mechanism of volatile flavor in fermented tilapia surimi by cooperative fermentation of Pediococcus acidilactici and Latilactobacillus sakei: Quantization of microbial contribution through influence of genus.
Single starter can hardly improve the volatile flavor of fermented fish surimi. In this study, the changes of volatile compounds (VCs) and microbial composition during cooperative fermentation of Latilactobacillus sakei and Pediococcus acidilactici were studied by headspace solid-phase microextraction gas chromatography-mass spectrometry and 16S rRNA gene high-throughput sequencing. During cooperative fermentation, most VCs and the abundance of Latilactobacillus and Lactococcus significantly increased, while Pediococcus, Acinetobacter, and Macrococcus obviously decreased. After evaluation of correlation and abundance of each genus, Latilactobacillus and Lactococcus possessed the highest influence on the formation of volatile flavor during cooperative fermentation. Compared with the natural fermentation, cooperative fermentation with starters significantly enhanced most of pleasant core VCs (odor activity value≥1), but inhibited the production of trimethylamine and methanethiol, mainly resulting from the absolutely highest influence of Latilactobacillus. Cooperative fermentation of starters is an effective method to improve the volatile flavor in the fermented tilapia surimi.
Topics: Volatile Organic Compounds; Animals; Fermentation; Pediococcus acidilactici; Fish Products; Latilactobacillus sakei; Tilapia; Taste; Flavoring Agents; Fermented Foods; Gas Chromatography-Mass Spectrometry
PubMed: 38604034
DOI: 10.1016/j.foodchem.2024.139239