High-altitude and low-altitude adapted chicken gut-microbes have different functional diversity.

Recently, there has been considerable interest in the functions of gut microbiota in broiler chickens in relation to their use as feed additives. However, the gut-microbiota of chickens reared at different altitudes are not well documented for their potential role in adapting to prevailing conditions and functional changes. In this context, the present study investigates the functional diversity of gut-microbes in high-altitude (HACh) and low-altitude adapted chickens (LACh), assessing their substrate utilization profile through Biolog Ecoplates technology. This will help in the identification of potential microbes or their synthesized metabolites, which could be beneficial for the host or industrial applications. Results revealed that among the 31 different types of studied substrates, only polymers, carbohydrates, carboxylic acids, and amine-based substrates utilization varied significantly (p < 0.05) among the chickens reared at two different altitudes where gut-microbes of LACh utilized a broad range of substrates than the HACh. Further, diversity indices (Shannon and MacIntosh) analysis in LACh samples showed significant (p < 0.05) higher richness and evenness of microbes as compared to the HACh samples. However, no significant difference was observed in the Simpson diversity index in gut microbes of lowversus high-altitude chickens. In addition, the Principal Component Analysis elucidated variation in substrate preferences of gut-microbes, where 13 and 8 carbon substrates were found to constitute PC1 and PC2, respectively, where γ-aminobutyric acid, D-glucosaminic acid, i-erythritol and tween 40 were the most relevant substrates that had a major effect on PC1, however, alpha-ketobutyric acid and glycyl-L-glutamic acid affected PC2. Hence, this study concludes that the gut-microbes of high and low-altitudes adapted chickens use different carbon substrates so that they could play a vital role in the health and immunity of an animal host based on their geographical location. Consequently, this study substantiates the difference in the substrate utilization and functional diversity of the microbial flora in chickens reared at high and low altitudes due to altitudinal changes.

Tackling Salmonella Persister Cells by Antibiotic-Nisin Combination via Mannitol.

Bacterial persisters (defined as dormant, non-dividing cells with globally reduced metabolism) are the major cause of recurrent infections. As they neither grow nor die in presence of antibiotics, it is difficult to eradicate these cells using antibiotics, even at higher concentrations. Reports of metabolites (which help in waking up of these inactive cells) enabled eradication of bacterial persistence by aminoglycosides, suggest the new potential strategy to improve antibiotic therapy. Here we propose, mannitol enabled elimination of Salmonella persister cells by the nisin-antibiotic combination. For this, persister cells were developed and characterized for their typical properties such as non-replicative state and metabolic dormancy. Different carbon sources viz. glucose, glycerol, and mannitol were used, each as an adjunct to ampicillin for the eradication of persister cells. The maximum (but not complete) killing was observed with mannitol-ampicillin, out of all the combinations used. However, significant elimination (about 78%) could be observed, when nisin (an antimicrobial peptide) was used with ampicillin in presence of mannitol, which might have mediated the transfer of antibiotic-nisin combination at the same time when the cells tried to grab the carbon molecule. Further, the effectiveness of the trio was confirmed by flow cytometry. Overall, our findings highlight the potential of this trio-combination for developing it as an option for tackling Salmonella persister cells.