生物化学与分析生物化学

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2015 年生物技术大会：生长条件（温度和氧气供应）对活菌和高压灭菌乳酸乳球菌 (Lactococcuslactisvar.lactis) 吸附锰 (II) 的影响 NCIMB 6681 - Sandra BorkowskaHeurtaux - 格拉斯哥卡利多尼亚大学

桑德拉·博科斯卡-赫托、科林·亨特和阿利斯泰尔·萨瑟兰

锰 (II) 是人类、动物和植物正常生长发育所必需的元素，但它有在某些生物体内积累的趋势，导致食物链中锰含量升高，具有潜在毒性。研究了乳酸乳球菌 (Lactococcuslactisvar.lactis) 对锰 2+ 的吸附特性，该菌是一种广泛用于乳制品行业的非致病性细菌，研究了四种生长条件下的锰 2+ 吸附特性：细胞在 30°C 和 37°C 下进行有氧和低氧培养。此外，还比较了活细胞和高压灭菌细胞的生物吸附特性。乳酸乳球菌在 5 天内表现出非常有竞争力的锰 2+ 吸附能力，实验悬浮液中的 pH 漂移表明离子交换机制参与了锰 2+ 吸附。通过连续稀释和平板计数法研究了乳酸乳球菌在吸附实验中的活力，在接触时间 24 小时和 72 小时时观察到细胞数量的最大减少。在四种不同条件下培养的活乳酸菌对 Mn(II) 的吸附能力为 34-50 mg/gdw。高压灭菌生物质表现出低得多的吸附能力（20-39 mg/gdw），但这一范围是以前使用各种（非活）生物质的研究中观察到的对 Mn2+ 的最高去除能力之一。所得结果是第一份报告，显示了 L. lactis 的活细胞和高压灭菌细胞对 Mn2+ 的吸附与不同的生长条件和金属负荷的关系。这也是首批研究活细胞和死细胞之间差异的研究之一。 细菌素 ST34BR 是一种由乳酸乳球菌亚种提供的 2.9 kDa 小多肽。 lactis ST34BR 可抑制粪肠球菌、大肠杆菌、植物乳杆菌、干酪乳杆菌、铜绿假单胞菌和金黄色葡萄球菌的生长。MRS 原液，pH 值调整至 6.0，产生 6,400 AU/ml，而 BHI 原液、M17 原液、10% (w/v) 豆奶和 8% 和 10% (w/v) 糖蜜中记录的 400 AU/ml。pH 值为 4.5 时，仅产生 800 AU/ml。根据对不含天然氮、用胰蛋白胨、肉浓缩物和酵母分离物的各种混合物增强的 MRS 原液进行的类似研究，胰蛋白胨被确定为活跃的氮化合物。在 20 g/l 葡萄糖、麦芽糖、甘露糖或蔗糖浓度下培养可产生 6,400 AU/ml 的细菌素水平，而乳糖和果糖浓度相同时分别产生 3,200 AU/ml 和 1,600 AU/ml。在用 2 g/l K2HPO4 和 2 g/l、5 g/l、10 g/l 或 50 g/l KH2PO4 增强的 MRS 原液中，细菌素 ST34BR 活性没有差异。然而，20 g/l KH2PO4 可将细菌素 ST34BR 的产生量增加至 12,800 AU/ml。 MRS 原液中 1g/l 至 10 g/l 的甘油使细菌素迁移率降低至 3,200 AU/ml，而 20 g/l 和 50 g/l 的甘油仅产生 1,600 AU/ml。氰钴胺素、L �? � 抗坏血酸、硫胺素和 dl �? � 6,8 �? � 的接近性thioctic corrosive in MRS stock at 1.0 ppm, individually, didn't bring about expanded action levels. (© 2004 WILEY�?�VCH Verlag GmbH and Co. KGaA, Weinheim)Oxygen is a significant determinant of both endurance and mortality of oxygen consuming life forms. For the facultative anaerobe Lactococcus lactis, oxygen effectsly affects both development and endurance. We appear here that oxygen can be helpful to L. lactis if heme is available during circulated air through development. The development time frame is broadened and long haul endurance is particularly improved contrasted with results acquired under the standard aging conditions. We thought about that improved development and endurance could be because of the limit of L. lactis to experience breath. To test this thought, we affirmed that the metabolic conduct of lactococci within the sight of oxygen and hemin is reliable with breath and is most articulated late in development. We at that point utilized a hereditary way to deal with show the accompanying. (I) The cydA quality, encoding cytochrome d oxidase, is required for breath and assumes an immediate job in oxygen usage. cydA articulation is incited late in development under breath conditions. (ii) The hemZ quality, encoding ferrochelatase, which changes over protoporphyrin IX to heme, is required for breath if the forerunner, as opposed to the last heme item, is available in the medium. Shockingly, endurance improved by breath is seen in a superoxide dismutase-inadequate strain, an outcome which underlines the physiological contrasts among maturing and breathing lactococci. These examinations affirm respiratory digestion in L. lactis and propose that this living being might be preferable adjusted to breath over to customary fermentative digestion. The poisonous cell impacts of oxygen are a central point in maturing and mortality. Oxygen poisonousness is ascribed to the action of receptive oxygen species that assault proteins, lipids, and nucleic acids. Impacts of oxygen have been widely concentrated by utilization of bacterial models, chiefly with the facultatively breathing bacterium Escherichia coli.

 

In this model, breath itself is embroiled as a wellspring of oxidative harm in E. coli. It has been proposed that the shutdown of breath in supplement constrained conditions may diminish responsive oxygen species levels and in this way improve E. coli endurance. Ongoing proof further recommends that endurance is supported by moving cells to anaerobic conditions during passage into fixed stage. Current data on the impacts of oxygen is predominantly founded on breathing living beings. In that capacity, the subject of what anaerobes do within the sight of oxidative pressure has been investigated close to nothing. It is assumed that these creatures adapt to worry similarly as aerobes, then again, actually their barrier frameworks, which may incorporate superoxide dismutases (SODs) and catalases, might be progressively restricted. Be that as it may, there has been no exhibition to date that reactions of anaerobes to an oxidative domain are unsurprising from the conduct of breathing microbes. The impacts of oxygen have been analyzed with Lactococcus lactis, a gram-positive facultative anaerobe with a fermentative digestion that can utilize various sugars to create essentially l-(+)- lactic corrosive. Oxygenation of societies brings about a changed redox state and more prominent NADH oxidase action; as a result, sugar aging is moved toward blended aging, and acidic corrosive, formic corrosive, CO2, ethanol, and acetoin, just as lactic corrosive, are created. Regardless of its grouping as an anaerobe and studies that have concentrated almost altogether on its fermentative digestion, results got around 30 years prior proposed that L. lactis can experience respiratory development, given that heme is added to circulated air through societies; this view was upheld by an exhibition of adjusted metabolic final results, cytochrome arrangement, and hemin-subordinate oxygen take-up. Nonetheless, later investigations of a L. lactis subsp. diacetylactis strain proposed that breath doesn't happen under these conditions, as cytochromes couldn't be recognized.

 

To date this inquiry has not been additionally investigated, and the results of respiratory development have not been examined. The harmful impacts of oxygen on L. lactis development and endurance have been uncovered by a few examinations under maturation conditions. Development is supposedly restrained by oxygen, and delayed air circulation of lactococcal societies can prompt cell passing and DNA corruption. Oxygen harmfulness might be because of development of hydrogen peroxide and hydroxyl radicals. In contrast to E. coli, L. lactis has a solitary SOD and no catalase. It was discovered that the expansion of exogenous catalase improved endurance of L. lactis cells presented to oxygen. These outcomes recommend that L. lactis may not be completely prepared to withstand the poisonous impacts of an oxidative domain.

 

我们对氧毒性的研究促使我们分析了外源过氧化氢酶的增加对乳酸乳球菌生长和耐力的积极影响。由于过氧化氢酶含有血红素核心（其中铁与卟啉原子络合），我们首先分析了血红素视野中氧气的影响。我们确认乳酸乳球菌能够进行呼吸生长，这与之前的研究一致。与正常衰老条件下的生长相比，呼吸条件导致生长加快，长期耐力显著提高。观察到的表型需要无缺陷的 cydA 基因，该基因编码细胞色素 d 氧化酶。在呼吸条件下，成熟发生在早期生长期间，而呼吸在后期指数阶段最为显著。（1999 年 9 月，在荷兰费尔德霍芬举行的乳酸会议上首次介绍了呼吸及其对乳球菌的影响的初步口腔对应关系。