Abstract:

With glsA1 in BJ3-2 as the homologous sequence, glutaminase gene glsA2 with high activity was targeted and
integrated into the Bacillus subtilis BJ3-2 chromosome by constructing a single-exchange integrative vector. A recombinant
strain BJ3-2A2 was obtained with good genetic stability. The results of detection showed that glutaminase activity in the
recombinant strain was 3.36 times higher than that in the original strain BJ3-2. The amino acid contents in douchi fermented
with BJ3-2A2 and the original BJ3-2 were measured, and the results showed that glutamate content in fermentation products
from the recombinant strain was increased by 12.8% as compared to that observed with the original strain. All the analyses
show that B. subtilis BJ3-2 is transformable as a RecE+ strain and that glutaminase gene glsA2 can be highly expressed in the
BJ3-2 chromosome, thus improving the flavour of douchi.

Key words: Bacillus subtilis, homologous recombinant, single-exchange, glutaminase-encoding gene