Van't Hul J S, Gibbons W R
Biology/Microbiology Department, South Dakota State University, Brookings 57007, USA.
Biotechnol Appl Biochem. 1996 Dec;24(3):251-6.
This investigation compared various techniques to concentrate and recover nisin from Lactococcus lactis cells. Centrifugation, combined with pH manipulation, was initially investigated as it is known that nisin will adsorb to producer cells at pH 6.5 and desorb at pH < or = 3.0. Unfortunately, centrifugation stripped producer cells of nisin even at pH 6.5; therefore a milder separation process (microfiltration) was evaluated. Results using a medium (LTB) containing peptone, tryptone, yeast extract, NaCl, Na2HPO4 and glucose demonstrated that nisin could be at least partially concentrated with cells via microfiltration. However, when a filtered stillage-based medium was used, nisin production was boosted to levels which exceeded the holding capacity of producer cells, resulting in release of nisin from cells at pH 6.5. Since it appears unfeasible to use producer cells for nisin recovery, an alternative may be to separately immobilize cells/ fragments in a re-usable column to act as a "resin' to adsorb nisin. Microfiltration could then be used to release nisin from cells, with nisin recovered by passing the permeated material through the immobilized-cell columns at pH 6.5.
本研究比较了从乳酸乳球菌细胞中浓缩和回收乳酸链球菌素的各种技术。最初研究了离心结合pH调节的方法，因为已知乳酸链球菌素在pH 6.5时会吸附到生产细胞上，而在pH≤3.0时会解吸。不幸的是，即使在pH 6.5时，离心也会使生产细胞中的乳酸链球菌素脱附；因此，评估了一种更温和的分离过程（微滤）。使用含有蛋白胨、胰蛋白胨、酵母提取物、NaCl、Na2HPO4和葡萄糖的培养基（LTB）的结果表明，乳酸链球菌素可以通过微滤至少部分地与细胞一起浓缩。然而，当使用基于过滤后的釜馏物的培养基时，乳酸链球菌素的产量提高到超过生产细胞容纳能力的水平，导致在pH 6.5时乳酸链球菌素从细胞中释放出来。由于使用生产细胞回收乳酸链球菌素似乎不可行，另一种选择可能是将细胞/片段单独固定在可重复使用的柱中，作为吸附乳酸链球菌素的“树脂”。然后可以使用微滤从细胞中释放乳酸链球菌素，通过使渗透物质在pH 6.5时通过固定化细胞柱来回收乳酸链球菌素。
