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Recruiting a new strategy to improve levan production in Bacillus amyloliquefaciens.

Feng J, Gu Y, Quan Y, Zhang W, Cao M, Gao W, Song C, Yang C, Wang S - Sci Rep (2015)

Bottom Line: Microbial levan is an important biopolymer with considerable potential in food and medical applications.Furthermore, the NK-Q-7 strain also showed a 94.1% increase in α-amylase production compared with NK-ΔLP strain, suggesting a positive effect of extracellular protease genes deficient on the production of endogenously secreted proteins.This is the first report of the improvement of levan production in microbes deficient in extracellular proteases and TasA, and the NK-Q-7 strain exhibits outstanding characteristics for extracellular protein production or extracellular protein related product synthesis.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Nankai University, Tianjin 300071, China.

ABSTRACT
Microbial levan is an important biopolymer with considerable potential in food and medical applications. Bacillus amyloliquefaciens NK-ΔLP strain can produce high-purity, low-molecular-weight levan, but production is relatively low. To enhance the production of levan, six extracellular protease genes (bpr, epr, mpr, vpr, nprE and aprE), together with the tasA gene (encoding the major biofilm matrix protein TasA) and the pgsBCA cluster (responsible for poly-γ-glutamic acid (γ-PGA) synthesis), were intentionally knocked out in the Bacillus amyloliquefaciens NK-1 strain. The highest levan production (31.1 g/L) was obtained from the NK-Q-7 strain (ΔtasA, Δbpr, Δepr, Δmpr, Δvpr, ΔnprE, ΔaprE and ΔpgsBCA), which was 103% higher than that of the NK-ΔLP strain (ΔpgsBCA) (15.3 g/L). Furthermore, the NK-Q-7 strain also showed a 94.1% increase in α-amylase production compared with NK-ΔLP strain, suggesting a positive effect of extracellular protease genes deficient on the production of endogenously secreted proteins. This is the first report of the improvement of levan production in microbes deficient in extracellular proteases and TasA, and the NK-Q-7 strain exhibits outstanding characteristics for extracellular protein production or extracellular protein related product synthesis.

No MeSH data available.


Related in: MedlinePlus

γ-PGA fermentation results in the B. amyloliquefaciens NK-1 and mutant NK-P-X strains after 48 h of cultivation.Values represent the means ± SD. Asterisks indicate significant difference from the NK-1 strain (P < 0.05). All cultures were repeated at least five times.
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f4: γ-PGA fermentation results in the B. amyloliquefaciens NK-1 and mutant NK-P-X strains after 48 h of cultivation.Values represent the means ± SD. Asterisks indicate significant difference from the NK-1 strain (P < 0.05). All cultures were repeated at least five times.

Mentions: The effects of the deletion of tasA and the six-extracellular protease genes on γ-PGA production were characterized in this work. The γ-PGA fermentation results obtained from B. amyloliquefaciens NK-1 and the gene deletion mutant strains are shown in Fig. 4. γ-PGA production remained unchanged after deleting the tasA, bpr, epr and mpr genes. However, the NK-P-5 strain, harboring further deletion of the vpr gene, showed increased γ-PGA production. The NK-P-5 strain exhibited the highest γ-PGA yield, which was a 24.2% increase compared with the NK-1 strain, leading to a titer of 4.62 g/L, compared with 3.72 g/L for the control. γ-PGA production was lower in the strains in which the nprE and aprE genes were deleted. γ-PGA production from the NK-P-7 strain was 2.19 g/L, which was 47.4% lower than in the NK-P-5 strain. Moreover, the dry cell weight (DCW) of the NK-P-7 strain was lower than other strains, and this strain was observed to enter the cell decline phase earlier.


Recruiting a new strategy to improve levan production in Bacillus amyloliquefaciens.

Feng J, Gu Y, Quan Y, Zhang W, Cao M, Gao W, Song C, Yang C, Wang S - Sci Rep (2015)

γ-PGA fermentation results in the B. amyloliquefaciens NK-1 and mutant NK-P-X strains after 48 h of cultivation.Values represent the means ± SD. Asterisks indicate significant difference from the NK-1 strain (P < 0.05). All cultures were repeated at least five times.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4561895&req=5

f4: γ-PGA fermentation results in the B. amyloliquefaciens NK-1 and mutant NK-P-X strains after 48 h of cultivation.Values represent the means ± SD. Asterisks indicate significant difference from the NK-1 strain (P < 0.05). All cultures were repeated at least five times.
Mentions: The effects of the deletion of tasA and the six-extracellular protease genes on γ-PGA production were characterized in this work. The γ-PGA fermentation results obtained from B. amyloliquefaciens NK-1 and the gene deletion mutant strains are shown in Fig. 4. γ-PGA production remained unchanged after deleting the tasA, bpr, epr and mpr genes. However, the NK-P-5 strain, harboring further deletion of the vpr gene, showed increased γ-PGA production. The NK-P-5 strain exhibited the highest γ-PGA yield, which was a 24.2% increase compared with the NK-1 strain, leading to a titer of 4.62 g/L, compared with 3.72 g/L for the control. γ-PGA production was lower in the strains in which the nprE and aprE genes were deleted. γ-PGA production from the NK-P-7 strain was 2.19 g/L, which was 47.4% lower than in the NK-P-5 strain. Moreover, the dry cell weight (DCW) of the NK-P-7 strain was lower than other strains, and this strain was observed to enter the cell decline phase earlier.

Bottom Line: Microbial levan is an important biopolymer with considerable potential in food and medical applications.Furthermore, the NK-Q-7 strain also showed a 94.1% increase in α-amylase production compared with NK-ΔLP strain, suggesting a positive effect of extracellular protease genes deficient on the production of endogenously secreted proteins.This is the first report of the improvement of levan production in microbes deficient in extracellular proteases and TasA, and the NK-Q-7 strain exhibits outstanding characteristics for extracellular protein production or extracellular protein related product synthesis.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Nankai University, Tianjin 300071, China.

ABSTRACT
Microbial levan is an important biopolymer with considerable potential in food and medical applications. Bacillus amyloliquefaciens NK-ΔLP strain can produce high-purity, low-molecular-weight levan, but production is relatively low. To enhance the production of levan, six extracellular protease genes (bpr, epr, mpr, vpr, nprE and aprE), together with the tasA gene (encoding the major biofilm matrix protein TasA) and the pgsBCA cluster (responsible for poly-γ-glutamic acid (γ-PGA) synthesis), were intentionally knocked out in the Bacillus amyloliquefaciens NK-1 strain. The highest levan production (31.1 g/L) was obtained from the NK-Q-7 strain (ΔtasA, Δbpr, Δepr, Δmpr, Δvpr, ΔnprE, ΔaprE and ΔpgsBCA), which was 103% higher than that of the NK-ΔLP strain (ΔpgsBCA) (15.3 g/L). Furthermore, the NK-Q-7 strain also showed a 94.1% increase in α-amylase production compared with NK-ΔLP strain, suggesting a positive effect of extracellular protease genes deficient on the production of endogenously secreted proteins. This is the first report of the improvement of levan production in microbes deficient in extracellular proteases and TasA, and the NK-Q-7 strain exhibits outstanding characteristics for extracellular protein production or extracellular protein related product synthesis.

No MeSH data available.


Related in: MedlinePlus