Improvement of poly--glutamic acid (PGA) producing Bacillus subtilis SB-MYP-1 by N-methyl-N-nitro-N-nitrosoguanidine (NTG) mutagenesis

Mahidsanan T., . and Gasaluck P., . Improvement of poly--glutamic acid (PGA) producing Bacillus subtilis SB-MYP-1 by N-methyl-N-nitro-N-nitrosoguanidine (NTG) mutagenesis. pp. 751-755. ISSN 2231-7546

Poly--glutamic acid (PGA) found in the mucilage of fermented soybean is synthesized by Bacillus sp. Its derivatives have been used as cryoprotectants bitterness-relieving agents thickeners and humectants in the ingredient industry. The wild type of Bacillus subtilis SB-MYP-1 isolated from fermented soybean was found to have a low efficacy to synthesize PGA during fermentation. Chemical induced mutation is generally introduced to provide microbial metabolite improvements. N-methyl-N-nitro-N-nitrosoguanidine (NTG) was reported to have an ability to improve the microbial metabolite production. This mutagen induced nitrogenous base substitution at the replication point of protein syntheses. The work aimed to improve the B. subtilis SB-MYP-1 PGA production using random NTG mutagenesis. The appropriate mutation sensitivity of survival rate was selected on 0.001-10 according to 40-90 g/ml NTG of a total 147 mutant isolates. Consequently screened PGA-producing mutants were spotted on PGA agar and the slime diameter (mm.) of nine isolates was higher than that of the wild type (P0.05). Those of nine mutant isolates were quantified for PGA production in PGA broth at 37oC for 36 h. Five isolates (NTG-17 NTG-53 NTG-88 NTG-132 and NTG-146) produced the PGA higher than the wild type (P0.05). In addition the selected five NTG mutants provided the maximum PGA production and growth steadily in L-glutamic acid supplement-submerged fermentation at 37oC during 12-72 h. The characteristics of genomic DNA band of the five mutant isolates by random primer (5-AGTCAGCCAC-3) with a random amplified polymorphic DNA (RAPD) technique were similar to those of the wild type. However the PGA production profile changes of NTG mutants could be exploited for the PGA-producing strain improvement.

Full text available from: Official URL: http://www.ifrj.upm.edu.my/23%20(02)%202016/(40).p...

Abstract

Poly--glutamic acid (PGA) found in the mucilage of fermented soybean is synthesized by Bacillus sp. Its derivatives have been used as cryoprotectants bitterness-relieving agents thickeners and humectants in the ingredient industry. The wild type of Bacillus subtilis SB-MYP-1 isolated from fermented soybean was found to have a low efficacy to synthesize PGA during fermentation. Chemical induced mutation is generally introduced to provide microbial metabolite improvements. N-methyl-N-nitro-N-nitrosoguanidine (NTG) was reported to have an ability to improve the microbial metabolite production. This mutagen induced nitrogenous base substitution at the replication point of protein syntheses. The work aimed to improve the B. subtilis SB-MYP-1 PGA production using random NTG mutagenesis. The appropriate mutation sensitivity of survival rate was selected on 0.001-10 according to 40-90 g/ml NTG of a total 147 mutant isolates. Consequently screened PGA-producing mutants were spotted on PGA agar and the slime diameter (mm.) of nine isolates was higher than that of the wild type (P0.05). Those of nine mutant isolates were quantified for PGA production in PGA broth at 37oC for 36 h. Five isolates (NTG-17 NTG-53 NTG-88 NTG-132 and NTG-146) produced the PGA higher than the wild type (P0.05). In addition the selected five NTG mutants provided the maximum PGA production and growth steadily in L-glutamic acid supplement-submerged fermentation at 37oC during 12-72 h. The characteristics of genomic DNA band of the five mutant isolates by random primer (5-AGTCAGCCAC-3) with a random amplified polymorphic DNA (RAPD) technique were similar to those of the wild type. However the PGA production profile changes of NTG mutants could be exploited for the PGA-producing strain improvement.

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Item Type:	Article
AGROVOC Term:	Glutamic acid
AGROVOC Term:	Bacillus subtilis
AGROVOC Term:	Fermentation
AGROVOC Term:	Mutagenesis
AGROVOC Term:	Nitrosoguanidine
AGROVOC Term:	Mucilages
AGROVOC Term:	Cryoprotectants
Depositing User:	Ms. Suzila Mohamad Kasim
Last Modified:	24 Apr 2025 06:27
URI:	http://webagris.upm.edu.my/id/eprint/22609

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