Cr (VI) being used in various activities of industries and its improper treatment lead to contamination of environment. Among different methods, biological is the most efficient method to control pollution from soils affected with metals. Present study was designed to assess the role of Paenibacillus thiaminolyticus PS5 for adsorption, Cr (VI) reduction and mechanism of reduction. Sorption of chromium (VI) by strain PS5 was obtained by batch equilibrium method. Cr (VI) reduction in both free and immobilised cells were evaluated by 1,5-Diphenyl Carbazide method. The formation of biofilm by Paenibacillus thiaminolyticus PS5 was observed for colour change as well as quantified spectrophotometrically. Analysis kits were used to measure the amount of eDNA, superoxide and malondialdehyde (MDA). Metal resistant strain PS5 was characterised as P. thiaminolyticus using 16S rRNA gene sequence. Maximum biosorption of Cr (VI) by strain PS5 was found at pH 6–8 and 100–400 µgCr/mL within 24 hours of incubation. Complete reduction of Cr (VI) by strain PS5 was achieved at pH 6–8 and100–300 µg/mL Cr (VI). Paenibacillus thiaminolyticus PS5 immmobilisation on sodium alginate and polyvinyl alcohol facilitated complete reduction of Cr (VI) within 18 hours due to the formation of more biofilm under metal stress conditions. Strain PS5 reduced almost all Cr (VI) into Cr (III) in supernatant, most of which was immobilised by cell debris. Experiments confirmed the reduction of Cr (VI) by cytosolic cell-free extracts which is a mechanism of detoxification. The release of exopolysaccharides and antioxidants by strain PS5 played a protective role against cell damage by Cr (VI) as Cr (VI) could not release the significant amount of eDNA, superoxide and MDA. The present study proved strain PS5 to be a super bioinoculant which has great capacity for adsorption, biotransformation and can activate cytosolic reductases, exopolysaccharides and antioxidants against oxidative damage.

六价铬在工业的各种活动中使用，对其处理不当会导致环境污染。在不同的方法中，生物学是控制金属污染土壤最有效的方法。本研究旨在评估解氨硫巴氏芽孢杆菌PS5在吸附，Cr（VI）还原和还原机理中的作用。通过分批平衡法获得了PS5对铬（VI）的吸附。通过1,5-二苯基咔嗪方法评估游离和固定化细胞中Cr（VI）的减少。硫解巴氏杆菌生物膜的形成观察到PS5的颜色变化以及分光光度法定量。分析试剂盒用于测量eDNA，超氧化物和丙二醛（MDA）的量。使用16S rRNA基因序列将金属抗性菌株PS5表征为解氨硫杆菌。在孵育的24小时内，在pH 6-8和100-400 µgCr / mL的条件下，菌株PS5对Cr（VI）的最大生物吸附作用。在pH 6-8和100-300 µg / mL Cr（VI）下，菌株PS5完全还原了Cr（VI）。解氨硫杆菌由于在金属应力条件下形成了更多的生物膜，PS5在藻酸钠和聚乙烯醇上的固定化促进了Cr（VI）在18小时内的完全还原。PS5菌株将上清液中的几乎所有Cr（VI）还原为Cr（III），其中大部分被细胞碎片固定。实验证实，无胞质提取物可减少Cr（VI），这是解毒的一种机制。PS5菌株释放胞外多糖和抗氧化剂起到了保护细胞免受Cr（VI）损伤的作用，因为Cr（VI）不能释放大量的eDNA，超氧化物和MDA。本研究证明PS5菌株是一种超级生物菌剂，具有强大的吸附，生物转化能力，并且可以激活胞质还原酶，胞外多糖和抗氧化剂以抵抗氧化损伤。