Bhavya Gurulingaiah, De Britto Savitha, Ali Daoud, Alarifi Saud, Abdelrahman Mostafa, Geetha Nagaraja, Jogaiah Sudisha
Nanobiotechnology Laboratory, Department of Studies in Biotechnology, University of Mysore, Manasagangotri, Mysuru, Karnataka, 570006, India.
Division of Biological Sciences, School of Science and Technology, University of Goroka, Goroka, 441, Papua New Guinea.
Folia Microbiol (Praha). 2025 Aug 15. doi: 10.1007/s12223-025-01309-w.
Indigenous bacteria are very potent and useful in remediating hazardous pollutants specific to particular geographical locations. This work aimed to isolate two potent acid red dye decolorizing bacterial strains, namely Bacillus sp. strain UoMP1 and Citrobacter sp. strain UoMP2, from a textile effluent sample and aimed to optimize the conditions and explore the probable enzymatic involvement. The two isolates, namely D2 and D3, exhibited tolerance towards dye in an optimized concentration range of 2-4%. The decolourization percentage was approximately 80% for D2 and 75% for D3. The optimized conditions for decolourization were 72 h of incubation, pH 7, and a temperature of 37 °C. It is well known that the enzymes from the class reductase play a key role in the decolourization of various dyes and other xenobiotics. In this study, the azoreductase activity in D2 and D3 was found to be remarkably high under optimal conditions. The maximal intracellular azoreductase activity was 6.5 and 2.5 µg of acid dye reduced/min per mg of protein in D2 and D3 isolates, respectively. In the D2 isolate, an increased concentration of extracellular polysaccharides under dye stress suggested a possible role of extracellular decolourization and complexation mechanisms. Based on the 16 s RNA gene amplification, sequencing, and analysis, D2 and D3 were identified as Bacillus sp. strain UoMP1 and Citrobacter sp. strain UoMP2, respectively. Bacillus sp. strain UoMP1, an indigenous bacterial isolate, was found to be very efficient in decolourization of an azo dye-acid red dye used in the silk industry. This study provides valuable insights into the non-toxic tolerable dye concentration for these bacterial cells, which employ both enzyme-based decolourization mechanisms and extracellular mechanisms via extracellular polysaccharide production. Further exploration of biochemical and molecular mechanisms will help refine these isolates for field applications.
本地细菌在修复特定地理位置的有害污染物方面非常有效且实用。这项工作旨在从纺织废水样本中分离出两种高效的酸性红染料脱色细菌菌株，即芽孢杆菌属菌株UoMP1和柠檬酸杆菌属菌株UoMP2，并旨在优化条件并探索可能涉及的酶。这两种分离株，即D2和D3，在2-4%的优化浓度范围内表现出对染料的耐受性。D2的脱色率约为80%，D3为75%。脱色的优化条件是孵育72小时、pH值为7、温度为37°C。众所周知，还原酶类的酶在各种染料和其他异生素的脱色中起关键作用。在本研究中，发现D2和D3在最佳条件下的偶氮还原酶活性非常高。D2和D3分离株中最大的细胞内偶氮还原酶活性分别为每毫克蛋白质每分钟还原6.5和2.5微克酸性染料。在D2分离株中，染料胁迫下细胞外多糖浓度的增加表明细胞外脱色和络合机制可能发挥作用。基于16s RNA基因扩增、测序和分析，D2和D3分别被鉴定为芽孢杆菌属菌株UoMP1和柠檬酸杆菌属菌株UoMP2。芽孢杆菌属菌株UoMP1是一种本地细菌分离株，被发现对偶氮染料——丝绸工业中使用的酸性红染料具有非常高效的脱色能力。这项研究为这些细菌细胞的无毒可耐受染料浓度提供了有价值的见解，这些细菌细胞采用基于酶的脱色机制和通过细胞外多糖产生的细胞外机制。对生化和分子机制的进一步探索将有助于优化这些分离株以用于实际应用。
