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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.

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Related in: MedlinePlus

GPC results for γ-PGA and levan products.(a) GPC spectrum of γ-PGA obtained from B. amyloliquefaciens NK-1 and (b) GPC spectrum of levan obtained from B. amyloliquefaciens NK-ΔLP.
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f6: GPC results for γ-PGA and levan products.(a) GPC spectrum of γ-PGA obtained from B. amyloliquefaciens NK-1 and (b) GPC spectrum of levan obtained from B. amyloliquefaciens NK-ΔLP.

Mentions: B. amyloliquefaciens NK-1 is derived from the LL3 strain, which was isolated from fermented food (Korea bibimbap paste)9, thus it is safe for human beings. In our previous work, we found that the NK-1 strain could co-produce γ-PGA and levan simultaneously (Fig. 6a). After deleting the pgsBCA cluster, the obtained NK-ΔLP strain could not produce γ-PGA, and the remaining product mainly consisted of levan, at a purity reaching 92.7% (Fig. 6b) 7. From our previously work, we determined that the bacteria could produce levan products of two different molecular weights. Higher-molecular-weight levan is produced at early timepoints and is then hydrolyzed to lower-molecular-weight levan by levanase, and the low-molecular-weight levan is dominant after 48 h of fermentation7. The levan molecular weight obtained from the NK-ΔLP strain was mostly around 5 kDa7, which is significantly lower than other reported levan products8. However, levan production needs to be improved to meet the requirements for industrial application34.


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)

GPC results for γ-PGA and levan products.(a) GPC spectrum of γ-PGA obtained from B. amyloliquefaciens NK-1 and (b) GPC spectrum of levan obtained from B. amyloliquefaciens NK-ΔLP.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f6: GPC results for γ-PGA and levan products.(a) GPC spectrum of γ-PGA obtained from B. amyloliquefaciens NK-1 and (b) GPC spectrum of levan obtained from B. amyloliquefaciens NK-ΔLP.
Mentions: B. amyloliquefaciens NK-1 is derived from the LL3 strain, which was isolated from fermented food (Korea bibimbap paste)9, thus it is safe for human beings. In our previous work, we found that the NK-1 strain could co-produce γ-PGA and levan simultaneously (Fig. 6a). After deleting the pgsBCA cluster, the obtained NK-ΔLP strain could not produce γ-PGA, and the remaining product mainly consisted of levan, at a purity reaching 92.7% (Fig. 6b) 7. From our previously work, we determined that the bacteria could produce levan products of two different molecular weights. Higher-molecular-weight levan is produced at early timepoints and is then hydrolyzed to lower-molecular-weight levan by levanase, and the low-molecular-weight levan is dominant after 48 h of fermentation7. The levan molecular weight obtained from the NK-ΔLP strain was mostly around 5 kDa7, which is significantly lower than other reported levan products8. However, levan production needs to be improved to meet the requirements for industrial application34.

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