Department of Biotechnology, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, 22100 Lund, Sweden.
J Food Prot. 2010 May;73(5):960-6. doi: 10.4315/0362-028x-73.5.960.
Pediococcus parvulus 2.6 (previously Pediococcus damnosus 2.6, here confirmed as P. parvulus by 16S DNA sequencing) displayed antibacterial activity toward several bacterial species, including isolates found as contaminants in oats, herein genetically identified as Bacillus cereus. No inhibition of Listeria monocytogenes was found under the conditions used. Antibacterial activity was retrieved after ammonium sulfate or acetone precipitation showed it to be peptide mediated. P. parvulus 2.6 has previously shown good technological properties in oat-based products. This, together with the currently found inhibition of food spoilage microorganisms like B. cereus, makes it suitable as a food protective culture. Survival trials of P. parvulus 2.6 at conditions mimicking the gastrointestinal tract were prompted by previously found cholesterol-lowering effects in humans after consumption of oat products cofermented by using P. parvulus 2.6 and Bifidobacterium spp. Viability was measured with in vitro, gutlike simulations at 37 degrees C. High survival was shown under two of three conditions (gastric juice, bile, and small intestine juice), defined as main obstacles of the gastrointestinal tract. The critical step was bile exposure. At a concentration of 20%, viability was low, but 0.3% bile (mean concentration in the intestine) did not have a major influence on growth. Viability of P. parvulus 2.6 was significantly decreased in gastric juice at pH 1.5 (with pepsin), but it was not significantly affected at pH 2.5, and was also improved at a lower pH in 20% oat milk. Viability was judged sufficient for colonization at gutlike conditions, qualifying the strain for further probiotic studies.
小葡萄球菌 2.6（以前称为腐败亚种 2.6，通过 16S DNA 测序，这里被确认为小葡萄球菌）对几种细菌表现出抗菌活性，包括在燕麦中发现的作为污染物的分离物，在此被鉴定为蜡样芽孢杆菌。在所使用的条件下，没有发现对单核细胞增生李斯特菌的抑制作用。硫酸铵或丙酮沉淀后回收抗菌活性，表明其由肽介导。小葡萄球菌 2.6 先前在燕麦基产品中表现出良好的技术特性。这一点，再加上目前发现的对食品腐败微生物如蜡样芽孢杆菌的抑制作用，使它适合作为一种食品保护培养物。在模拟胃肠道条件的生存试验是由先前发现的人类在食用由小葡萄球菌 2.6 和双歧杆菌属共同发酵的燕麦产品后降低胆固醇的效果所引发的。使用体外、模拟肠道条件在 37°C 下测量了存活率。在三种条件中的两种（胃液、胆汁和小肠液）下显示出高存活率，被定义为胃肠道的主要障碍。关键步骤是胆汁暴露。在 20%的浓度下，存活率较低，但 0.3%的胆汁（肠道中的平均浓度）对生长没有重大影响。在 pH 值为 1.5（有胃蛋白酶）的胃液中小葡萄球菌 2.6 的存活率显著降低，但在 pH 值为 2.5 时没有显著影响，在 20%的燕麦乳中较低的 pH 值也能提高存活率。在模拟肠道条件下的存活率被判断为足以定植，使该菌株有资格进行进一步的益生菌研究。
