Exploitation of acid-tolerant microbial species for the utilization of low-cost whey in the production of acetic acid and propylene glycol
Exploitation of acid-tolerant microbial species for the utilization of low-cost whey in the production of acetic acid and propylene glycol
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DOI：
10.1007/s00253-018-9174-3
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发表时间：
2018-06
影响因子：
5
通讯作者：
S. S. Veeravalli-S.;A. P. Mathews
中科院分区：
文献类型：
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作者：
S. S. Veeravalli-S.;A. P. Mathews
来自奶酪和酸奶生产过程的乳清含有有用的成分，例如乳清蛋白和乳糖。然而，分离和提取过程困难且成本高昂，因此，乳清的最终用户需求有限，并且通常作为废物处置。这些高生化需氧量废物的处理和处置既耗能又昂贵。然而，这些废物处置不当会污染地表和地下水资源。使用这些低成本或负成本底物生产乙酸和丙二醇（PG）等增值产品对于将管理成本转变为收入流具有重要意义。本研究的重点是用乳清乳糖和含有乳糖和蛋白质的乳清粉生物生产乙酸和PG，作为高成本营养培养基的替代品。研究发现，布氏乳杆菌是一种耐酸细菌，当以乳糖为主要碳底物时，能够在 pH ~ 4.2 的条件下将乳糖发酵为浓度为 25–30 g L−1 的低分子量化合物，例如乙酸和 PG。发酵结束时乙酸与 PG 的典型摩尔比接近 1:1。使用棉粗棉布作为固定基质的高细胞密度发酵提高了乙酸和PG的生产率。使用乳清粉和固定化发酵系统表现出与在 pH 4.2 下添加纯乳糖的培养物相似的性能，导致乳清中乳糖总共 57% 转化为乙酸盐和 PG，而化学计量最大值为 72%。
Whey from cheese and yoghurt production operations contains useful constituents such as whey protein and lactose. However, the separation and extraction processes are difficult and costly, and hence, whey has limited end user demand and is typically disposed of as waste. Treatment and disposal of these high BOD wastes are both energy intensive and expensive. However, improper disposal of these wastes can pollute surface and ground water resources. The use of these low or negative cost substrates for the production of value-added products such as acetic acid and propylene glycol (PG) is of great significance in changing overhead costs to revenue streams. The present study focuses on bioproduction of acetic acid and PG from whey lactose and whey powder containing lactose and protein as an alternative to high cost nutritive medium. It was found thatLactobacillus buchneri, an acid-tolerant bacterium, is able to ferment lactose at pH ~ 4.2 to low molecular weight compounds such as acetic acid and PG each at 25–30 g L−1concentration when using lactose as a major carbon substrate. The typical molar ratio of acetic acid to PG was close to 1:1 at the end of fermentation. The productivity of acetic acid and PG was improved using a high cell density fermentation with cotton cheesecloth as an immobilization matrix. The use of whey powder with immobilized fermentation system showed a similar performance to that of cultures fed with pure lactose at pH 4.2, resulting in a 57% conversion of lactose in whey to acetate and PG in total, against a stoichiometric maximum of 72%.