Enhancement of ε-polylysine production by Streptomyces albulus strain 410 using pH control

Mechanism of ε-Poly- l -Lysine Production and Accumulation Revealed by Identification and Analysis of an ε-Poly- l -Lysine-Degrading Enzyme

“…After incubation with shaking at 30°C for 20 h, the ε-PL concentrations were measured. ε-PL fermentation in a 3-liter bench-scale jar fermentor with strict pH control was performed according to the method reported by Kahar and coworkers (9). S. albulus NBRC14147 was inoculated into 5 ml of SLB medium and cultivated until the stationary phase was reached (for 20 h at 30°C).…”

“…In vitro, Pls produced ε-PL with chain lengths ranging from 3 to 17 residues, demonstrating that the chain length diversity of ε-PL is directly generated by the synthetase rather than via the differential degradation of a uniform polymer by ε-PLdegrading enzymes (22). However, in vivo, it is still unclear whether the 25 to 35 L-lysine residues of ε-PL represent the original chain length of the polymer product synthesized by Pls as strain NBRC14147 produces ε-PL-degrading enzymes (9).…”

“…During ε-PL fermentation, its production and accumulation are detected when the pH value of the fermentation broth decreases from approximately 7.0 to the self-stabilized final value of approximately 3.2 (9). After fermentation is complete, ε-PL is enzymatically degraded by increasing the pH value to approximately 7.0 (9).…”

Recent advances in the biotechnological production of microbial poly(ɛ-l-lysine) and understanding of its biosynthetic mechanism

“…Since the screening of the first ɛ-PL-producing strain, several fermentation strategies have been persistently pursued for high ɛ-PL productivity. The most classic fermentation strategy for ɛ-PL production is the two-phase pH control approach, and the ɛ-PL production titer reported with this approach was 48.3 g/L by Streptomyces albulus S410 (Kahar et al 2001). Surprisingly, this work was from 15 years ago, which might suggest that enhancing ɛ-PL at the current level is very difficult because of the toxicity of ɛ-PL on its own producing strain and the limited metabolic ability of the producers.…”

“…Further research suggested that the optimum pH for ɛ-PL accumulation was 4.0 and for cell growth was 6.0. Based on these results, Kahar et al improved the overall efficiency of ɛ-PL production from 5.7 to 40.3 g/L using S. albulus S410 with two distinct phases; in the first phase, the pH of the culture broth was maintained above 5.0 for cell growth, whereas the pH was maintained at pH 4.0 for ɛ-PL accumulation in the second phase (Kahar et al 2001).…”