Nisin production in realkalized fed-batch cultures in whey with feeding with lactose- or glucose-containing substrates
Nisin production in realkalized fed-batch cultures in whey with feeding with lactose- or glucose-containing substrates
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DOI：
10.1007/s00253-016-7558-9
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发表时间：
2016-09-01
影响因子：
5
通讯作者：
Perez Guerra, Nelson
中科院分区：
文献类型：
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作者：
Costas Malvido, Monica;Alonso Gonzalez, Elisa;Perez Guerra, Nelson
乳酸乳球菌CECT 539生产乳酸链球菌素的后续分批培养物中的乳清补充不同浓度的葡萄糖和两个realkalized补料分批发酵中未补充的乳清，这是美联储，分别与乳糖和葡萄糖的浓缩溶液。在分批发酵中，补充乳清与葡萄糖抑制生长和细菌素的生产。然而，补料分批培养物的特征在于与未补充乳清（0.48 g l（-1）和22.5 BU ml（-1））和MRS肉汤（1.59 g l（-1）和50.0 BU ml（-1））中的分批发酵相比，生物质（1.34和1.51 g l（-1））和乳链菌肽（50.6和60.3 BU ml（-1））的高产量。在两个再碱化补料分批发酵中，细菌素产量的增加与每个再碱化和补料循环中产生的生物量产量和pH下降平行，表明乳链菌肽是作为pH依赖性初级代谢产物合成的。在孵育108 h时观察到从同型乳酸发酵到异型乳酸发酵的转变，除乳酸外，培养基中还积累了其他代谢产物（乙酸和丁烷-2，3-二醇）。另一方面，与分批培养相比，用葡萄糖补料提高了葡萄糖、氮和磷消耗的效率。再碱化补料分批发酵是提高乳链菌肽生产的有效策略，通过使用适当的补料策略，以避免底物抑制。
Nisin production by Lactococcus lactis CECT 539 was followed in batch cultures in whey supplemented with different concentrations of glucose and in two realkalized fed-batch fermentations in unsupplemented whey, which were fed, respectively, with concentrated solutions of lactose and glucose. In the batch fermentations, supplementation of whey with glucose inhibited both the growth and bacteriocin production. However, fed-batch cultures were characterized with high productions of biomass (1.34 and 1.51 g l(-1)) and nisin (50.6 and 60.3 BU ml(-1)) in comparison to the batch fermentations in unsupplemented whey (0.48 g l(-1) and 22.5 BU ml(-1)) and MRS broth (1.59 g l(-1) and 50.0 BU ml(-1)). In the two realkalized fed-batch fermentations, the increase in bacteriocin production parallels both the biomass production and pH drop generated in each realkalization and feeding cycle, suggesting that nisin was synthesized as a pH-dependent primary metabolite. A shift from homolactic to heterolactic fermentation was observed at the 108 h of incubation, and other metabolites (acetic acid and butane-2,3-diol) in addition to lactic acid accumulated in the medium. On the other hand, the feeding with glucose improved the efficiencies in glucose, nitrogen, and phosphorus consumption as compared to the batch cultures. The realkalized fed-batch fermentations showed to be an effective strategy to enhance nisin production in whey by using an appropriate feeding strategy to avoid the substrate inhibition.