Isolation, characterization, and interaction of lignin-degrading bacteria from rumen of buffalo (Bubalus bubalis).

The purpose of this study was to isolate lignin-degrading bacteria from buffalo rumen and to explore their interactions further. Using lignin as the carbon source, three bacteria, B-04 (Ochrobactrum pseudintermedium), B-11 (Klebsiella pneumoniae), and B-45 (Bacillus sonorensis), which have shown lignin degradation potential, were successfully isolated and identified from the rumen fluid of buffalo by colony morphology, 16S ribosomal RNA gene sequencing, and biochemical and physiological analyses. The degradation rates of lignin were determined, and the maximum values were 4.86%, 11.1%, and 7.68% for B-04, B-11, and B-45, respectively. The maximum laccase activities were 0.65, 0.93, and 1.15 U/ml, while the maximum lignin peroxidase activities were 5.72, 8.29, and 18.69 U/ml, respectively. Pairwise interaction studies showed inhibitory interaction between B-04 and B-45, inhibitory interaction between B-04 and B-11, and symbiotic interaction between B-11 and B-45. This is the first report on the lignin degradation ability of bacteria isolated from the buffalo's rumen, which provides a new understanding for revealing the mechanism of roughage tolerance of buffalo.

Evaluation and mining the applicable methods of roughage digestibility determination for buffalo (Bubalus bubalis).

Buffalo is an amazing ruminant with high tolerance to low-quality roughage. Due to the special breeding environment, there are few reports on the digestibility of roughage in buffalo because it is difficult to quantify ingestion and egestion. To find more applicable method to determine the digestibility of low-quality roughage in buffalo, this study was conducted to compare total feces collection (TFC) method with the following three indirect techniques: Cr2O3 (chromic oxide), AIA (acid-insoluble ash), and ADL (acid detergent lignin), to determine rice straw digestibility in buffalo. Six non-pregnant, non-lactating female buffaloes were used in this experiment and the nutritional compositions of the rice straw and feces were measured. Using Cr2O3 and AIA methods, the digestibility of dry matter (DM), ash, organic matter (OM), nitrogen free extract (NFE), crude protein (CP), ether extract (EE), crude fiber (CF), neutral detergent fiber (NDF), acid detergent fiber (ADF), cellulose (CEL), hemicellulose (HC), and ADL did not have statistically significant differences compared with TFC (P > 0.05). However, the digestibility of DM, ash, OM, NFE, EE, CF, NDF, ADF, and ADL determined using ADL method were significantly lower than those using the TFC (P < 0.05). The feces recovery of Cr2O3 and AIA was 95.89% and 97.14%, which were higher than that of ADL (88.90%). In summary, compare with ADL method, TFC, Cr2O3, and AIA methods are more accurate to determine the roughage digestibility of buffalo. Furthermore, Cr2O3 and AIA methods are applicable and convenient to evaluate the roughage digestibility of buffalo under extensive feeding system.