Background: The Tibetan pig is a pig breedwith excellent grazing
characteristics indigenous to the Qinghai\u2013Tibet plateau in China.
Under conditions of barn feeding, 90% of its diet consists of forage
grass, which helps meet its nutritional needs. The present study aimed
to isolate and identify a cellulolytic bacterium from the Tibetan pig's
intestine and investigate cellulase production by this bacterium. The
study purpose is to provide a basic theory for the research and
development of herbivore characteristics and to identify a source of
probiotics from the Tibetan pig. Results: A cellulolytic bacterium was
isolated from a Tibetan pig's intestine and identified based on
morphological, physiological, and biochemical characteristics as well
as 16S rRNA analysis; it was designated Bacillus subtilis BY-2.
Examination of its growth characteristics showed that its growth curve
entered the logarithmic phase after 8\u201312 h and the stable growth
phase being between 20 and 40 h. The best carbon source for
fermentation was 1% corn flour, while 2% peptone and yeast powder
compound were the best nitrogen sources. The initial pH during
fermentation was 5.5, with 4% inoculum, resulting in a high and stable
amount of enzyme in 24\u201348 h. Conclusions: The isolated BY-2
strain rapidly grew and produced cellulase.We believe that BY-2
cellulase can help overcome the shortage of endogenous animal
cellulase, improve the utilization rate of roughage, and provide strain
sources for research on porcine probiotics