[Improving heat and pH stability of nisin by site-directed mutagenesis].
OBJECTIVE
The aim of this study was to optimize the property of nisin through altering its specific amino acid by site-directed mutagenesis method.


METHODS
On the basis of M21K nisinZ, a former reported nisinZ mutant that exhibited antimicrobial activity against Gram-negative bacteria, the 29th amino acid of it was mutated from serine to lysine. The mutant M21K/S29K nisZ gene was cloned into vector pMG36e and the recombinant plasmid was introduced into Lacotococcus lactis NZ9800. The resulting M21K/S29K nisinZ was then isolated and purified, and its antibacterial activity, antibacterial spectrum and stability were analyzed and compared to those of M21K nisinZ and nisinZ.


RESULTS
Compared with wild-type nisinZ and M21K nisinZ, the M21K/S29K nisinZ displayed reduced antimicrobial activity, but showed significantly increased stabilities to heat and pH stress. Moreover, M21K/S29K nisinZ also exhibited antimicrobial activity against Gram-negative bacteria as M21K nisinZ did.


CONCLUSIONS
By changing the 29th amino acid of nisin, we can optimize the property of nisin, especially its stability to heat and pH stress.
Colleges of Life Science, Anhui Agricultural University, Hefei 230036, China. luyao_6@hotmail.com
Yao
Y
Lu
Like
L
Jiang
Meiling
M
Chen
Liandong
L
Huan
Jin
J
Zhong
D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D001419:Bacteria / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005818:Genetic Engineering; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D016297:Mutagenesis, Site-Directed; D009561:Nisin / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism
D000900:Anti-Bacterial Agents; D009561:Nisin