Tuli Shanjana Rahman, Ali Md Firoz, Jamal Tabassum Binte, Khan Md Abu Sayem, Fatima Nigar, Ahmed Irfan, Khatun Masuma, Sharmin Shamima Akhtar
Environmental Biotechnology Division, National Institute of Biotechnology, Ganakbari, Ashulia, Savar, Dhaka 1349, Bangladesh.
Department of Biotechnology and Genetic Engineering, Mawlana Bhashani Science and Technology University, Santosh, Tangail 1902, Bangladesh.
Microorganisms. 2024 Dec 19;12(12):2633. doi: 10.3390/microorganisms12122633.
Environmental pollution from metal toxicity is a widespread concern. Certain bacteria hold promise for bioremediation via the conversion of toxic chromium compounds into less harmful forms, promoting environmental cleanup. In this study, we report the isolation and detailed characterization of a highly chromium-tolerant bacterium, CRB14. The isolate is capable of growing on 5000 mg/L Cr (VI) in an LB (Luria Bertani) agar plate while on 900 mg/L Cr (VI) in LB broth. It shows an 86.57% reduction ability in 96 h of culture. It can also tolerate high levels of As, Cd, Co, Fe, Zn, and Pb. The isolate also shows plant growth-promoting potential as demonstrated by a significant activity of nitrogen fixation, phosphate solubilization, IAA (indole acetic acid), and siderophore production. Whole-genome sequencing revealed that the isolate lacks Cr resistance genes in their plasmids and are located on its chromosome. The presence of the gene points towards Cr(VI) transport, while the absence of suggests alternative reduction pathways. The genome harbors features like genomic islands and CRISPR-Cas systems, potentially aiding adaptation and defense. Analysis suggests robust metabolic pathways, potentially involved in Cr detoxification. Notably, genes for siderophore and NRP-metallophore production were identified. Whole-genome sequencing data also provides the basis for molecular validation of various genes. Findings from this study highlight the potential application of CRB14 for bioremediation while plant growth promotion can be utilized as an added benefit.
金属毒性造成的环境污染是一个广泛关注的问题。某些细菌有望通过将有毒的铬化合物转化为危害较小的形式来进行生物修复，从而促进环境清理。在本研究中，我们报告了一种高度耐铬细菌CRB14的分离和详细表征。该分离株能够在LB（Luria Bertani）琼脂平板上的5000 mg/L Cr（VI）以及LB肉汤中的900 mg/L Cr（VI）上生长。在培养96小时后，它显示出86.57%的还原能力。它还能耐受高水平的砷、镉、钴、铁、锌和铅。该分离株还表现出促进植物生长的潜力，如固氮、解磷、产生吲哚乙酸（IAA）和铁载体的显著活性所示。全基因组测序表明，该分离株在其质粒中缺乏抗铬基因，这些基因位于其染色体上。该基因的存在指向Cr（VI）的转运，而该基因的缺失表明存在其他还原途径。该基因组具有基因组岛和CRISPR-Cas系统等特征，可能有助于适应和防御。分析表明存在强大的代谢途径，可能参与铬的解毒。值得注意的是，已鉴定出铁载体和NRP-金属载体产生的基因。全基因组测序数据也为各种基因的分子验证提供了基础。本研究的结果突出了CRB14在生物修复方面的潜在应用，同时促进植物生长可作为一项附加益处加以利用。
