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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

Cell pellicle formation in the B. amyloliquefaciens NK-1, B. amyloliquefaciens NK-P-1, B. amyloliquefaciens NK-Q-1 and B. amyloliquefaciens NK-ΔLP strains.Cells were cultured at 30 °C for 72 h in MSgg broth in a six-well microtiter dish.
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f3: Cell pellicle formation in the B. amyloliquefaciens NK-1, B. amyloliquefaciens NK-P-1, B. amyloliquefaciens NK-Q-1 and B. amyloliquefaciens NK-ΔLP strains.Cells were cultured at 30 °C for 72 h in MSgg broth in a six-well microtiter dish.

Mentions: Our previous work showed that B. amyloliquefaciens NK-1 could form structurally complex biofilms30. Genetic, biochemical and cytological evidences suggested that this complex extracellular matrix is mainly composed of TasA and Eps and the absence of TasA or Eps results in a residual matrix1731. Levan and γ-PGA also contribute to bacterial biofilm formation, cross-linking with other components to make the biofilm complete3233. Biofilm formation by the NK-1, NK-P-1, NK-Q-1 and NK-ΔLP strains was observed and the results were shown in Fig. 3. As expected, the NK-1 strain was able to form a complete pellicle, whereas the tasA gene deletion NK-P-1 strain could only form a deficient, incomplete pellicle. Unexpectedly, neither of the pgsBCA genes deletion strains (NK-Q-1 and NK-ΔLP) could form a pellicle. This result indicates that γ-PGA is the main component of the biofilm formed by the γ-PGA-producing strain and that the strain with deficient γ-PGA production could not form a biofilm.


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)

Cell pellicle formation in the B. amyloliquefaciens NK-1, B. amyloliquefaciens NK-P-1, B. amyloliquefaciens NK-Q-1 and B. amyloliquefaciens NK-ΔLP strains.Cells were cultured at 30 °C for 72 h in MSgg broth in a six-well microtiter dish.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f3: Cell pellicle formation in the B. amyloliquefaciens NK-1, B. amyloliquefaciens NK-P-1, B. amyloliquefaciens NK-Q-1 and B. amyloliquefaciens NK-ΔLP strains.Cells were cultured at 30 °C for 72 h in MSgg broth in a six-well microtiter dish.
Mentions: Our previous work showed that B. amyloliquefaciens NK-1 could form structurally complex biofilms30. Genetic, biochemical and cytological evidences suggested that this complex extracellular matrix is mainly composed of TasA and Eps and the absence of TasA or Eps results in a residual matrix1731. Levan and γ-PGA also contribute to bacterial biofilm formation, cross-linking with other components to make the biofilm complete3233. Biofilm formation by the NK-1, NK-P-1, NK-Q-1 and NK-ΔLP strains was observed and the results were shown in Fig. 3. As expected, the NK-1 strain was able to form a complete pellicle, whereas the tasA gene deletion NK-P-1 strain could only form a deficient, incomplete pellicle. Unexpectedly, neither of the pgsBCA genes deletion strains (NK-Q-1 and NK-ΔLP) could form a pellicle. This result indicates that γ-PGA is the main component of the biofilm formed by the γ-PGA-producing strain and that the strain with deficient γ-PGA production could not form a biofilm.

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