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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

Levan and α-amylase fermentation results in the B. amyloliquefaciens NK-ΔLP and mutant NK-Q-X strains.(a) Comparison of levan production and dry cell weights between NK-ΔLP and the mutant strains after 48 h of cultivation. (b) Comparison of α-amylase production and dry cell weights between NK-ΔLP and the mutant strains after 48 h of cultivation. Values represent the means ± SD. Asterisks indicate significant difference from the NK-ΔLP strain (P < 0.05). All cultures were repeated at least five times.
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f5: Levan and α-amylase fermentation results in the B. amyloliquefaciens NK-ΔLP and mutant NK-Q-X strains.(a) Comparison of levan production and dry cell weights between NK-ΔLP and the mutant strains after 48 h of cultivation. (b) Comparison of α-amylase production and dry cell weights between NK-ΔLP and the mutant strains after 48 h of cultivation. Values represent the means ± SD. Asterisks indicate significant difference from the NK-ΔLP strain (P < 0.05). All cultures were repeated at least five times.

Mentions: To evaluate the effect of the accumulation of gene-targeted B. amyloliquefaciens mutants on levan production, flask culture of B. amyloliquefaciens NK-ΔLP and the mutant strains was undertaken under identical conditions. We sought to delete the tasA gene for two reasons: (1) disruption of tasA can conserve energy and favor the production of levan via the metabolic flux; (2) Cells in biofilms are embedded in the extracellular matrix, which contains TasA, the major matrix protein. We speculated that by removing TasA, which is known to be bound to cells17, we may influence the export of extracellular levansucrase. Therefore it might have been possible that lack of TasA increases the production of levan. The fermentation results shown in Fig. 5a indicated that the deletion of tasA gene did affect levan production. The NK-Q-1 strain showed a slight 14.4% increase in levan production (17.5 g/L) compared with the NK-ΔLP strain (15.3 g/L).


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)

Levan and α-amylase fermentation results in the B. amyloliquefaciens NK-ΔLP and mutant NK-Q-X strains.(a) Comparison of levan production and dry cell weights between NK-ΔLP and the mutant strains after 48 h of cultivation. (b) Comparison of α-amylase production and dry cell weights between NK-ΔLP and the mutant strains after 48 h of cultivation. Values represent the means ± SD. Asterisks indicate significant difference from the NK-ΔLP 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

f5: Levan and α-amylase fermentation results in the B. amyloliquefaciens NK-ΔLP and mutant NK-Q-X strains.(a) Comparison of levan production and dry cell weights between NK-ΔLP and the mutant strains after 48 h of cultivation. (b) Comparison of α-amylase production and dry cell weights between NK-ΔLP and the mutant strains after 48 h of cultivation. Values represent the means ± SD. Asterisks indicate significant difference from the NK-ΔLP strain (P < 0.05). All cultures were repeated at least five times.
Mentions: To evaluate the effect of the accumulation of gene-targeted B. amyloliquefaciens mutants on levan production, flask culture of B. amyloliquefaciens NK-ΔLP and the mutant strains was undertaken under identical conditions. We sought to delete the tasA gene for two reasons: (1) disruption of tasA can conserve energy and favor the production of levan via the metabolic flux; (2) Cells in biofilms are embedded in the extracellular matrix, which contains TasA, the major matrix protein. We speculated that by removing TasA, which is known to be bound to cells17, we may influence the export of extracellular levansucrase. Therefore it might have been possible that lack of TasA increases the production of levan. The fermentation results shown in Fig. 5a indicated that the deletion of tasA gene did affect levan production. The NK-Q-1 strain showed a slight 14.4% increase in levan production (17.5 g/L) compared with the NK-ΔLP strain (15.3 g/L).

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