Isolation and characterization of strictly anaerobic cellulolytic rumen bacterial species from Sahiwal cattle.

Objective: To isolate and characterize cellulolytic rumen bacteria from the rumen of Sahiwal cattle using rumen bacterial inoculum to increase the nutritional value of rice bran used as broiler feed. Materials and Methods: The ruminal liquid was kept at an optimal pH of 6.9 and a redox potential of less than -300 mV while being incubated anaerobically at 39°C in a medium containing rumen fluid glucose cellobiose agar. By using the Hungate technique, the organisms were detected based on their morphological, physiological, biochemical, and molecular testing. Results: The findings revealed that the isolated Ruminococcus albus, and Ruminococcus flavifaciens were obligate anaerobic, generally Gram-positive, nonmotile cocci or rod, single or pair, occasionally short chain, producing yellow pigment when grown on cellulose, and having a clear zone around the colonies. Both isolate fermented sugars such as cellobiose, glucose, and lactose, as well as decomposed xylan. The results also showed that the isolates recognized as Ruminococcus spp., a cellulolytic rumen bacterium, were catalase-negative, indole-negative, and gelatin liquefaction-positive. Conclusion: Isolation and characterization of Ruminococcus spp. may be helpful for Bangladesh in reducing the cost of producing poultry feed and circumventing restrictions on rice bran use. We can also develop more efficient and long-lasting plans to enhance poultry performance and feed efficiency, as well as increase the nutritional value of rice bran used as broiler feed, by understanding how various Ruminococcus spp. function in this process.

Prevalence of Escherichia coli isolated from oropharynx and trachea of clinically sick poultry and antimicrobial resistance pattern of the strains isolated.

The study was carried out to investigate the isolation of Escherichia coli from tracheal and oropharyngeal swab of clinically sick chickens. The antibiotic susceptibility patterns of the isolates to several antimicrobials were determined with a striking emphasis on oxytetracycline. The PCR technique was applied to detect tetA, tetB, and tetC in the tetracycline-resistant isolates. The isolates were initially screened for their resistance patterns against 6 antimicrobials of six different groups using the disc diffusion technique. The results showed that 41% tracheal, 51% oropharyngeal, and 34% samples from both sites were E. coli positive respectively. Antimicrobial resistance profiling of the isolates revealed that all the isolates were resistant to oxytetracycline and sulphamethoxazole-trimethoprim, and also 90 %, 82.9%, 63.4%, and 39% resistant to ciprofloxacin, amoxicillin, gentamicin, and colistin respectively. Notably, 82.9% isolates (95% CI 68.4%-91.8%) showed resistance to ≥3 groups of antimicrobials that means these were multi-drug resistant. Among the tetracycline-resistant isolates, 85.4% (95% CI 71.2%-93.5%), 29.3% (7.5%-44.6%), and 7.3% (1.8% - 20.1) were positive for tetA, tetB, and tetC genes respectively. The frequency of the isolation of E. coli is greater in oropharyngeal than tracheal and both kinds of samples. Commercial poultry with E. coli strains has acquired extensive resistance to oxytetracycline. This study suggests a possible association between the tetA gene and oxytetracycline resistance in E. coli isolates, but further investigations like knockdown, whole-genome sequencing, and rescue experiments are needed to establish a direct causal relationship.