Metal polluted environments have been found to harbor acid and metal tolerant bacterial communities. Metal oxidizing bacteria in particular are industrially important microorganisms that can be utilized for potential applications in biomining and bioremediation. However, some well-characterized strains are not readily culturable as they are obligate and fastidious chemolithotrophs requiring special techniques for their cultivation. Hence, this study was aimed at isolating, identifying, and characterizing indigenous metal tolerant heterotroph(s) from abandoned mines that can potentially be used for biomining or bioremediation processes in the future. Seventeen bacteria from former mining lakes were isolated and identified using 16S rRNA. Minimal inhibition concentration (MIC) and growth study of isolated bacteria carried out in Luria-Bertani media containing three different metals ions, zinc (II), copper (II), and iron (II), showed that a particular isolate termed Enterobacter cloacae NZS was found to exhibit better growth and tolerance for copper (up to 90 mM), zinc (up to 200 mM), and iron (up to 170 mM). Growth of the strain was notably well in the presence of iron (II). Compared to all the isolates, only E. cloacae NZS was able to be enumerated at pH lower than 5 while other strains were culturable only at pH 7. Its capability in iron (II) oxidation was preliminary assessed based on the pH, cell count, glucose consumption, and amount of iron oxidized throughout incubation in 9K media. E. cloacae NZS strain was found to be capable of oxidizing iron (II) supplied in 9K media to iron (III). As preliminary investigation showed that E. cloacae NZS was able to oxidize iron (II) in 9K media at pH2, further optimization on the strain, medium, and culture conditions in future may be able to provide a better insight on this strain to be possibly used as an iron oxidizer for various applications.

中文翻译：

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来自马来西亚雪兰莪州前采矿湖的耐酸和耐金属阴沟肠杆菌 NZS 菌株的分离和表征

已发现金属污染的环境中存在耐酸和耐金属的细菌群落。特别是金属氧化细菌是工业上重要的微生物，可用于生物采矿和生物修复的潜在应用。然而，一些特征明确的菌株不容易培养，因为它们是专性和挑剔的化能生物，需要特殊的培养技术。因此，本研究旨在从废弃矿山中分离、鉴定和表征可用于未来生物采矿或生物修复过程的本地耐金属异养生物。使用 16S rRNA 分离并鉴定了来自前采矿湖的 17 种细菌。在含有三种不同金属离子锌 (II)、铜 (II) 和铁 (II) 的 Luria-Bertani 培养基中进行的分离细菌的最小抑制浓度 (MIC) 和生长研究表明，一种称为阴沟肠杆菌 NZS 的特定分离物发现对铜（高达 90 mM）、锌（高达 200 mM）和铁（高达 170 mM）表现出更好的生长和耐受性。在铁 (II) 的存在下，菌株的生长非常好。与所有分离株相比，只有阴沟肠杆菌 NZS 能够在 pH 低于 5 时计数，而其他菌株只能在 pH 7 下培养。 根据 pH、细胞计数、葡萄糖消耗量，以及在 9K 培养基中孵育过程中氧化的铁量。E. 发现 cloacae NZS 菌株能够将 9K 培养基中提供的铁 (II) 氧化为铁 (III)。由于初步调查表明阴沟肠杆菌 NZS 能够在 pH2 的 9K 培养基中氧化铁 (II)，未来进一步优化菌株、培养基和培养条件可能能够更好地了解该菌株，可能用作各种应用的铁氧化剂。