Genomic architecture of three newly isolated unclassified Butyrivibrio species elucidate their potential role in the rumen ecosystem

Impact of deoxynivalenol on rumen function, production, and health of dairy cows: Insights from metabolomics and microbiota analysis

Deoxynivalenol contamination in feed and food, pervasive from growth, storage, and processing, poses a significant risk to dairy cows, particularly when exposed to a high-starch diet; however, whether a high-starch diet exacerbates these negative effects remains unclear. Therefore, we investigated the combined impact of deoxynivalenol and dietary starch on the production performance, rumen function, and health of dairy cows using metabolomics and 16 S rRNA sequencing. Our findings suggested that both high- and low-starch diets contaminated with deoxynivalenol significantly reduced the concentration of propionate, isobutyrate, valerate, total volatile fatty acids (TVFA), and microbial crude protein (MCP) concentrations, accompanied by a noteworthy increase in NH3-N concentration in vitro and in vivo (P < 0.05). Deoxynivalenol altered the abundance of microbial communities in vivo, notably affecting Oscillospiraceae, Lachnospiraceae, Desulfovibrionaceae, and Selenomonadaceae. Additionally, it significantly downregulated lecithin, arachidonic acid, valine, leucine, isoleucine, arginine, and proline metabolism (P < 0.05). Furthermore, deoxynivalenol triggered oxidative stress, inflammation, and dysregulation in immune system linkage, ultimately compromising the overall health of dairy cows. Collectively, both high- and low-starch diets contaminated with deoxynivalenol could have detrimental effects on rumen function, posing a potential threat to production performance and the overall health of cows. Notably, the negative effects of deoxynivalenol are more pronounced with a high-starch diet than a low-starch diet.

Pseudodesulfovibrio thermohalotolerans sp. nov., a novel obligately anaerobic, halotolerant, thermotolerant, and sulfate-reducing bacterium isolated from a western offshore hydrocarbon reservoir in India

OBJECTIVE

Characterization and documentation of strain MCM B-1480T, a novel sulfate-reducing bacterium isolated from produced water of India's western offshore hydrocarbon reservoir.

METHOD

Strain MCM B-1480T was unequivocally identified using a polyphasic approach routinely followed in bacterial systematics. The morphological and biochemical characterization of strain MCM B-1480T was carried out using standard microbiological techniques.

RESULTS

MCM B-1480T was a Gram-stain-negative, motile, non-spore-forming, curved-rod-shaped bacterium. MCM B-1480T could grow at temperatures between 20 and 60 °C (optimum 37 °C), pH 6-8 (optimum 7), and required 1-6% NaCl (optimum 3%) for growth. Strain MCM B-1480T was reducing sulfate to produce hydrogen sulfide during growth. This strain used lactate and pyruvate as prominent electron donors, whereas sulfate, sulfite, thiosulfate, and nitrate served as electron acceptors. MCM B-1480T shared maximum 16S rRNA gene sequence homology of 98.65% with the members of the genus Pseudodesulfovibrio. The G + C content of the 3.87 Mb MCM B-1480T genome was 60.39%. Digital DDH (27.7%) and average nucleotide identity (ANI 84%) with the closest phylogenetic affiliate (less than 70% and 95%, respectively) reaffirmed its distinctiveness. The major cellular fatty acids components, namely iso-C15:0, anteiso-C15:0, C16:0, and anteiso-C17:0, differentiated strain MCM B-1480T from other species of Pseudodesulfovibrio. Genome annotation revealed the presence of genes encoding dissimilatory sulfate reduction and nitrate reduction in strain MCM B-1480T.

CONCLUSION

The polyphasic studies, including SSU rRNA gene sequencing, average nucleotide identity, Digital DNA-DNA hybridization, cell wall fatty acids analysis, etc., identified strain MCM B-1480T as a novel taxon and Pseudodesulfovibrio thermohalotolerans sp. nov. was proposed (= JCM 39269T = MCC 4711T).

Crystal Structures of Bacterial Pectin Methylesterases Pme8A and PmeC2 from Rumen Butyrivibrio

Pectin is a complex polysaccharide that forms a substantial proportion of the plant's middle lamella of forage ingested by grazing ruminants. Methanol in the rumen is derived mainly from methoxy groups released from pectin by the action of pectin methylesterase (PME) and is subsequently used by rumen methylotrophic methanogens that reduce methanol to produce methane (CH4). Members of the genus Butyrivibrio are key pectin-degrading rumen bacteria that contribute to methanol formation and have important roles in fibre breakdown, protein digestion, and the biohydrogenation of fatty acids. Therefore, methanol release from pectin degradation in the rumen is a potential target for CH4 mitigation technologies. Here, we present the crystal structures of PMEs belonging to the carbohydrate esterase family 8 (CE8) from Butyrivibrio proteoclasticus and Butyrivibrio fibrisolvens, determined to a resolution of 2.30 Å. These enzymes, like other PMEs, are right-handed β-helical proteins with a well-defined catalytic site and reaction mechanisms previously defined in insect, plant, and other bacterial pectin methylesterases. Potential substrate binding domains are also defined for the enzymes.

Description of Sporanaerobium hydrogeniformans gen. nov., sp. nov., an obligately anaerobic, hydrogen-producing bacterium isolated from Aravali hot spring in India

An obligately anaerobic bacterium XHS1971T, capable of degrading cellulose and xylan, was isolated from a sediment sample of Aravali hot spring, Ratnagiri, India. Cells of strain XHS1971T were Gram-stain-negative, spore-forming, motile, long-rods. Growth was observed at temperatures 30-50 °C (optimum 40-45 °C), pH 5.0-10.0 (optimum pH 8.0) and NaCl concentrations 0-0.5% (optimum 0%). Generation time of strain XHS1971T was 5 h under optimised growth conditions. Strain XHS1971T showed the ability to metabolise different complex and simple sugars constituting lignocellulosic biomass. Glucose was fermented majorly into hydrogen, formic acid, acetic acid, and ethanol, whereas carbon dioxide, butyric acid, lactic acid and succinic acid were produced in traces. 16S rRNA gene analysis of strain XHS1971T revealed < 94.5% homology with Cellulosilyticum lentocellum DSM5427T followed by Cellulosilyticum ruminicola JCM14822T, identifying strain as a distinct member of family Lachnospiraceae. The major cellular fatty acids (> 5%) were C14:0, C16:0, C18:0, and C16:1 ω7c. The genome size of the strain was 3.74 Mb with 35.3 mol% G + C content, and genes were annotated to carbohydrate metabolism, including genes involved in the degradation of cellulose and xylan and the production of hydrogen, ethanol and acetate. The uniqueness of strain was further validated by digital DNA-DNA hybridisation (dDDH), Average Nucleotide Identity (ANI), and Average Amino Acid Identity (AAI) values of 22%, 80%, and 63%, respectively, with nearest phylogenetic affiliates. Based on the detailed analyses, we propose a new genus and species, Sporanaerobium hydrogeniformans gen. nov., sp. nov., for strain XHS1971T (= MCC3498T = KCTC15729T = JCM32657T) within family Lachnospiraceae.

Actinomyces ruminis sp. nov., an obligately anaerobic bacterium isolated from the rumen of cattle

An obligately anaerobic, rod-shaped, Gram-stain-positive, non-spore-forming, non-motile bacterial strain; designated as CtC72^T was isolated from the rumen of cattle. The 16S rRNA gene sequence similarity of less than 98.65% revealed the strain as a member of the genus Actinomyces, nearest to but distinct from Actinomyces qiguomingii DSM 106201^T, Actinomyces ruminicola DSM 27982^T, Actinomyces procaprae JCM 33484^T, Actinomyces succiniciruminis TISTR 2317, Actinomyces glycerinitolerans TISTR 2318. The low values of digital DNA-DNA hybridization (< 70%) and average nucleotide identity (< 95%) further highlighted the distinctive nature of strain CtC72^T from its closest relatives. The strain CtC72^T could grow at temperatures between 30 and 50 °C (optimum 40 °C), pH between 6.0 and 9.0 (optimum 7.5-8.0), and NaCl between 0 and 1.5% (optimum 0%). The strain hydrolysed cellulose and xylan and utilised a range of mono-, di-, and oligo-saccharides as a source of carbon and energy. Glucose fermentation resulted in acetic acid and formic acid as major metabolic products, while propionic acid, lactic acid, and ethanol as minor products along with CO₂ production. The DNA G + C content of strain CtC72^T was 68.40 (mol%, T_m) and 68.05 (%, digital). Major cellular fatty acids (> 10%) were C_16:0, C_18:1 ω9c_, and C_18:1 ω9c DMA. Based on these data, we propose that strain CtC72^T be classified as a novel species, Actinomyces ruminis sp. nov., under the genus Actinomyces. The type strain is CtC72^T (= KCTC 15726^T = JCM 32641^T = MCC 3500^T).

A preliminary study on the possibility of fermented pineapple peel residue partially replacing whole corn silage in feeding Chuanzhong black goats

This study aims to assess the effects of the partial replacement of whole corn silage (WCS) with fermented pineapple peel residue (FPPR) on growth, serological parameters, muscle quality, rumen microorganisms, and fecal microorganisms. A total of 24 Chuanzhong black goats weighing 10.23 ± 1.42 kg were evaluated in a randomized complete trial design in accordance with the following treatments: (1) 0% FPPR in the diet, (2) 25% FPPR in the diet, and (3) 50% FPPR in the diet. In goats, the partial substitution of FPPR for WCS increased the abundance of probiotics, such as Blautia, Butyrivibrio fibrisolvens, and Ruminococcus albus, and did not exert significant effects on overall serological parameters and muscle quality. In conclusion, the partial substitution of FPPR for WCS in the diet did not impair or affect the productive performance of goats.