ε-聚赖氨酸(ε-poly-L-lysine,ε-PL)是Streptomyces albulus分泌产生的1种抗菌肽,主要用作生物食品防腐剂。为了进一步了解S. albulus积累ε-PL的影响因素,该文探究了恒化培养体系下不同pH值和菌体比生长速率对S. albulus M-Z18合成ε-PL的影响。结果发现,随着pH降低(D=0.04 h-1),细胞得率(YX/S)逐渐减小,葡萄糖比消耗速率(qS)、ε-PL比合成速率(qP)和胞内ATP浓度逐渐增加。与此相一致,随着菌体比生长速率增加(pH 4.0),qS、qP和胞内ATP浓度均呈逐渐增加趋势。因此,低pH和高菌体比生长速率都有助于S. albulus M-Z18高效积累ε-PL。该研究一方面为S. albulus在低pH环境积累ε-PL的原因提供了新的认识,另一方面也为后续通过提高细胞比生长速率而增加ε-PL产量的发酵优化提供了理论指导。
ε-Poly-L-lysine (ε-PL) is an antimicrobial peptide secreted by Streptomyces albulus and is mainly used as a biological food preservative. In order to further understand factors that affecting ε-PL production efficiency, different pH values and specific growth rates of S. albulus M-Z18 on the biosynthesis of ε-PL were investigated in this study. The results showed that the cell yield (YX/S) gradually reduced with the decrease of pH (D=0.04 h-1), while the specific glucose uptake rate (qS), specific ε-PL formation rate (qP), and intracellular ATP concentration gradually increased. Similarly, with the increase of specific growth rate (pH 4.0), qS, qP, and intracellular ATP concentration increased gradually. Therefore, both low pH environment and high specific cell growth rate contributed to efficient accumulation of ε-PL. These results provide a new insight for understanding why S. albulus accumulated ε-PL in low pH environment, and also provide a guidance for subsequent bioprocess optimization to increase ε-PL production.
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