US Department of Agriculture, Agricultural Research Service, SAA Food Science Research Unit, North Carolina State University, Raleigh, NC 27695-7624, USA.
Food Microbiol. 2013 Sep;35(2):129-35. doi: 10.1016/j.fm.2013.03.004. Epub 2013 Mar 21.
Recent evidence suggests that Lactobacillus buchneri may play an important role in spoilage-associated secondary fermentation of cucumbers. Lactic acid degradation during fermented cucumber spoilage is influenced by sodium chloride (NaCl) concentration, pH, and presence of oxygen. Objectives were to evaluate these factors on lactic acid utilization by L. buchneri, and to compare the biochemical changes to those which occur during fermented cucumber spoilage. Effects of NaCl (0, 2, 4, and 6% w/w), pH (3.8 vs 5.0), and aerobic environment were investigated using fermented cucumber media (FC) inoculated with spoilage microorganisms. At pH 3.8, L. buchneri degraded lactic acid in all NaCl concentrations. The highest rate of lactic acid utilization occurred in FC with 2% NaCl (P < 0.05). Lactic acid utilization was nearly identical under aerobic and anaerobic conditions, indicating that oxygen does not influence lactate metabolism by L. buchneri. Lactic acid utilization was accompanied by increases in acetic acid and 1,2-propanediol, and Lactobacillus rapi was able to convert 1,2-propanediol to propionic acid and propanol. L. buchneri initiated spoilage in a wide range of environmental conditions that may be present in commercial cucumber fermentations, and L. rapi may act syntrophically with L. buchneri to produce the commonly observed spoilage metabolites.
最近的证据表明，布氏乳杆菌可能在黄瓜腐败相关的二次发酵中发挥重要作用。发酵黄瓜腐败过程中乳酸的降解受氯化钠（NaCl）浓度、pH 值和氧气存在的影响。本研究旨在评估这些因素对布氏乳杆菌利用乳酸的影响，并将生化变化与发酵黄瓜腐败过程中的变化进行比较。使用接种腐败微生物的发酵黄瓜培养基（FC）研究了 NaCl（0、2、4 和 6%w/w）、pH 值（3.8 与 5.0）和有氧环境对乳酸利用的影响。在 pH 值为 3.8 时，布氏乳杆菌在所有 NaCl 浓度下都能降解乳酸。在含有 2%NaCl 的 FC 中，乳酸利用的速度最快（P<0.05）。有氧和无氧条件下乳酸利用几乎相同，表明氧气不会影响布氏乳杆菌的乳酸代谢。乳酸利用伴随着乙酸和 1,2-丙二醇的增加，并且乳杆菌 rap 能够将 1,2-丙二醇转化为丙酸和丙醇。布氏乳杆菌在商业黄瓜发酵中可能存在的广泛环境条件下引发腐败，并且乳杆菌 rap 可能与布氏乳杆菌协同作用产生常见的腐败代谢物。
