Isolation, Identification and Biological Characteristics Of Bacillus Subtilis  With High Cellulase Production From Sheep Intestine

Abstract

In recent years, microbial fermentation feed has played a vital role in animal production by improving the nutritional and functional properties of feed through the transformation of substrates and formation of bioactive or bioavailable end-products. The reasonable selection of strain is the key to improve fermentation efficiency. The primary indicator to screen for fermenting strains is the size of the cellulase production capacity, because the extracellular enzymes produced during probiotic fermentation can degrade the cell walls of plant cells, thereby releasing large amounts of nutrients in the feed. In this study, a total of eight strains were isolated from sheep intestines and one strain with high cellulase production was selected. Bacillus subtilis ECL1.2 was identified through morphology observation, Gram stain microscopy, biochemical tests, 16S rRNA PCR amplification and homology analysis. The strain showed the high ability to produce cellulase, proteases, α-amylase, and was sensitive to Escherichia coli, Salmonella and Staphylococcus aureus. Besides, ECL1.2 was sensitive to most antibiotics and resistant to Lincomycin. The addition of ECL 1.2 had no visible effect on intestinal and organ safety and increased daily weight gain and feed intake. In conclusion, the isolated strain ECL1.2 can be used as a potential strain for fermentation. In the future, its fermentation efficiency will be determined by detecting the active ingredient indicators fermented feed.

Keywords: Key words：Probiotics fermentation, cellulase, isolation and identification, biological characteristics, Bacillus subtilis