RESUMEN
The rumen microbiota contributes to greenhouse gas emissions and has an impact on feed efficiency and ruminant product fatty acid composition. Dietary fat supplements have shown promise in reducing enteric methane production and in altering the fatty acid profiles of ruminant-derived products, yet in vivo studies on how these impact the rumen microbiota are limited. In this study, we investigated the rumen bacterial, archaeal, fungal, and ciliate protozoan communities of dairy cows fed diets supplemented with 4 levels of docosahexaenoic acid (DHA) (0, 25, 50, and 75 g·cow(-1)·day(-1)) and established linkages between microbial communities and production parameters. Supplementation with DHA significantly (P < 0.05) altered rumen bacterial and archaeal, including methanogenic archaeal, communities but had no significant (P > 0.05) effects on rumen fungal or ciliate protozoan communities. Rumen bacterial communities of cows receiving no DHA were correlated with increased saturated fatty acids (C18:0 and C11:0) in their milk. Furthermore, rumen bacterial communities of cows receiving a diet supplemented with 50 g DHA·cow(-1)·day(-1) were correlated with increases in monounsaturated fatty acids (C20:1n-9) and polyunsaturated fatty acids (C22:5n-3; C22:6n-3; C18:2 cis-9, trans-11; C22:3n-6; and C18:2n-6 trans) in their milk. The significant diet-associated changes in rumen archaeal communities observed did not result in altered enteric methane outputs in these cows.
Asunto(s)
Suplementos Dietéticos , Ácidos Docosahexaenoicos/administración & dosificación , Microbiota , Rumen/microbiología , Animales , Archaea/clasificación , Archaea/genética , Archaea/aislamiento & purificación , Bacterias/clasificación , Bacterias/genética , Bacterias/aislamiento & purificación , Bovinos , Femenino , Lactancia , Metano/biosíntesis , Leche , Reacción en Cadena de la Polimerasa , Polimorfismo de Longitud del Fragmento de RestricciónRESUMEN
This study aimed to assess bacterial spoilage of half shell Pacific and Sydney rock oysters during storage using microbial culture and 16S rRNA pyrosequencing. Odour and pH of oyster meats were also investigated. Estimation of microbiological counts by microbial culture highlighted growth of psychrotrophic bacteria. During storage, odour scores (a score describing deterioration of fresh odours where a score of 1 is fresh and 4 is completely spoiled) increased from 1.0 to 3.0 for Pacific oysters and from 1.3 to 3.4 for Sydney rock oysters. pH results obtained for both species fluctuated during storage (range 6.28-6.73) with an overall increase at end of storage. Pyrosequencing revealed that the majority of bacteria at Day 0 represented taxa from amongst the Proteobacteria, Tenericutes and Spirochaetes that have not been cultured and systematically described. During storage, Proteobacteria became abundant with Pseudoalteromonas and Vibrio found to be dominant in both oyster species at Day 7. Analysis of the pyrosequencing data showed significant differences in bacterial profiles between oyster species and storage time (both P = 0.001). As oysters spoiled, bacterial profiles between oyster species became more similar indicating a common spoilage profile. Data presented here provides detailed insight into the changing bacterial profile of shucked oysters during storage and has identified two genera, Pseudoalteromonas and Vibrio, as being important in spoilage of shucked oysters.
Asunto(s)
Bacterias/aislamiento & purificación , Contaminación de Alimentos/análisis , Ostreidae/microbiología , Mariscos/microbiología , Animales , Bacterias/clasificación , Bacterias/genética , Bacterias/crecimiento & desarrollo , Humanos , Ostreidae/química , Pseudoalteromonas/clasificación , Pseudoalteromonas/genética , Pseudoalteromonas/crecimiento & desarrollo , Pseudoalteromonas/aislamiento & purificación , Mariscos/análisis , Gusto , Vibrio/clasificación , Vibrio/genética , Vibrio/crecimiento & desarrollo , Vibrio/aislamiento & purificaciónRESUMEN
An abnormal composition of the gut microbiota is believed to be associated with the pathogenesis of inflammatory bowel disease (IBD). We utilized terminal restriction fragment length polymorphism (T-RFLP) analysis to quantify faecal bacterial communities from rats with experimental colitis. Male Sprague Dawley rats (n=10/group) ingested 2% dextran sulfate sodium (DSS) or water for up to 7 days. Rats were killed and colonic tissues collected for histological analysis. Damage severity score in the distal colon was significantly greater (P<0.001) following DSS consumption compared to controls. T-RFLP faecal bacterial profiles generated with either MspI or CfoI revealed a significant difference (P<0.001) in community composition between healthy and colitic rats, with bacterial composition in healthy rats more variable than in rats with colitis. Operational taxonomic units (OTU: taxonomically related groups of bacteria) associated with either the healthy or colitic state were identified. OTU (116, 226, 360, and 948; CfoI) and (118 and 188; MspI) were strongly associated with untreated healthy rats, while OTU (94, 98, 174, and 384; CfoI) and (94 and 914; MspI) were predominantly associated with DSS-treated colitic rats. Phylogenetic OTU assignment suggested that Bacteroidales and Lactobacillus sp. were predominantly associated with the colitic and healthy rats, respectively. These results show that faecal bacterial profiling is a rapid, sensitive and non-invasive tool for detecting and identifying changes in gut microbiota associated with colitis. Restoring microbial homeostasis by targeting colitis-associated OTU through specific microbiological interventions could form the basis of novel therapeutic strategies for IBD.
Asunto(s)
Bacterias/aislamiento & purificación , Colitis/microbiología , Heces/microbiología , Metagenoma , Animales , Bacterias/clasificación , Bacterias/genética , Dermatoglifia del ADN , Modelos Animales de Enfermedad , Tracto Gastrointestinal/microbiología , Humanos , Masculino , Filogenia , Ratas , Ratas Sprague-DawleyRESUMEN
Three broiler feeding trials were investigated in order to identify gut bacteria consistently linked with improvements in bird performance as measured by feed efficiency. Trials were done in various geographic locations and varied in diet composition, broiler breed, and bird age. Gut microbial communities were investigated using microbial profiling. Eight common performance-linked operational taxonomic units (OTUs) were identified within both the ilea (180, 492, and 564-566) and ceca (140-142, 218-220, 284-286, 312, and 482) across trials. OTU 564-566 was associated with lower performance, while OTUs 140-142, 482, and 492 were associated with improved performance. Targeted cloning and sequencing of these eight OTUs revealed that they represented 26 bacterial species or phylotypes which clustered phylogenetically into seven groups related to Lactobacillus spp., Ruminococcaceae, Clostridiales, Gammaproteobacteria, Bacteroidales, Clostridiales/Lachnospiraceae, and unclassified bacteria/clostridia. Where bacteria were identifiable to the phylum level, they belonged predominantly to the Firmicutes, with Bacteroidetes and Proteobacteria also identified. Some of the potential performance-related phylotypes showed high sequence identity with classified bacteria (Lactobacillus salivarius, Lactobacillus aviarius, Lactobacillus crispatus, Faecalibacterium prausnitzii, Escherichia coli, Gallibacterium anatis, Clostridium lactatifermentans, Ruminococcus torques, Bacteroides vulgatus, and Alistipes finegoldii). The 16S rRNA gene sequence information generated will allow quantitative assays to be developed which will enable elucidations of which of these phylotypes are truly performance related. This information could be used to monitor strategies to improve feed efficiency and feed formulation for optimal gut health.
Asunto(s)
Bacterias/clasificación , Bacterias/crecimiento & desarrollo , Biodiversidad , Ciego/microbiología , Pollos/microbiología , Dieta/métodos , Íleon/microbiología , Animales , Bacterias/genética , Bacterias/aislamiento & purificación , Peso Corporal , Pollos/crecimiento & desarrollo , Análisis por Conglomerados , ADN Bacteriano/química , ADN Bacteriano/genética , ADN Ribosómico/química , ADN Ribosómico/genética , Datos de Secuencia Molecular , Filogenia , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADNRESUMEN
The effects of avilamycin, zinc bacitracin, and flavophospholipol on broiler gut microbial community colonization and bird performance in the first 17 days posthatch were investigated. Significant differences in gut microbiota associated with gut section, dietary treatment, and age were identified by terminal restriction fragment length polymorphism (T-RFLP), although no performance-related differences between dietary treatments were detected. Similar age-related shifts in the gut microbiota were identified regardless of diet but varied between the ilea and ceca. Interbird variabilities in ileal bacterial communities were reduced (3 to 7 days posthatch) in chicks fed with feed containing antimicrobial agents. Avilamycin and flavophospholipol had the most consistent effect on gut microbial communities. Operational taxonomic units (OTU) linked to changes in gut microbiota in birds on antimicrobial-supplemented diets were characterized and identified. Some OTUs could be identified to the species level; however, the majority could be only tentatively classified to the genus, family, order, or domain level. OTUs 140 to 146 (Lachnospiraceae), OTU 186/188 (Lactobacillus johnsonii), OTU 220 (Lachnospiraceae), OTUs 284 to 288 (unclassified bacterial spp. or Ruminococcaceae), OTU 296/298 (unclassified bacterium or Clostridiales), and OTU 480/482 (Oxalobacteraceae) were less prevalent in the guts of chicks fed antimicrobial-supplemented diets. OTU 178/180 (Lactobacillus crispatus), OTU 152 (Lactobacillus reuteri or unclassified Clostridiales), OTU 198/200 (Subdoligranulum spp.), and OTU 490/492 (unclassified bacterium or Enterobacteriaceae) were less prevalent in the gut of chicks raised on the antimicrobial-free diet. The identification of key bacterial species influenced by antimicrobial-supplemented feed immediately posthatch may assist in the formulation of diets that facilitate beneficial gut microbial colonization and, hence, the development of alternatives to current antimicrobial agents in feed for sustainable poultry production.