Untangling the adaptive strategies of thermophilic bacterium Anoxybacillus rupiensis TPH1 under low temperature.

The present study investigates the low temperature tolerance strategies of thermophilic bacterium Anoxybacillus rupiensis TPH1, which grows optimally at 55 °C , by subjecting it to a temperature down-shift of 10 °C (45 °C) for 4 and 6 h followed by studying its growth, morphophysiological, molecular and proteomic responses. Results suggested that although TPH1 experienced increased growth inhibition, ROS production, protein oxidation and membrane disruption after 4 h of incubation at 45 °C yet maintained its DNA integrity and cellular structure through the increased expression of DNA damage repair and cell envelop synthesizing proteins and also progressively alleviated growth inhibition by 20% within two hours i.e., 6 h, by inducing the expression of antioxidative enzymes, production of unsaturated fatty acids, capsular and released exopolysaccharides and forming biofilm along with chemotaxis proteins. Conclusively, the adaptation of Anoxybacillus rupiensis TPH1 to lower temperature is mainly mediated by the synthesis of large numbers of defense proteins and exopolysaccharide rich biofilm formation.

Decoding whole genome of Anoxybacillus rupiensis TPH1 isolated from tatapani hot spring, India and giving insight into bioremediation ability of TPH1 via heavy metals and azo dyes.

A moderately thermophilic, gram-positive genomospecies Anoxybacillus rupiensis TPH1 was isolated from Tatapani hot spring, Chhattisgarh, India. Genome of 3.70 Mb with 42.3% GC subsumed 4131 CDSs, 65 tRNA, 5 rRNA, 35 AMR and 19 drug target genes. Further, comparative genomics of 19 Anoxybacillus spp. exhibited an open pan genome of 13102 genes along with core (10.62%), unique (43.5%) and accessory (45.9%) genes. Moreover, phylogenomic tree displayed clustering of Anoxybacillus spp. into two distinct clades where clade A species harbored larger genomes, more unique genes, CDS and hypothetical proteins than clade B species. Further, distribution of azoreductases showed FMN-binding NADPH azoreductase (AzoRed1) presence in clade A species only and FMN-binding NADH azoreductase (AzoRed2) harboring by species of both clades. Heavy metal resistance genes distribution showed omnipresence of znuA, copZ and arsC in both clades, dispersed presence of cbiM, czcD, merA and feoB over both clades and harboring of nikA and acr3 by few species of clade A only. Additionally, molecular docking of AzoRed1, AzoRed2, ZnuA, CopZ, Acr3, CbiM, CzcD, MerA and NikA with their respective ligands indicated high affinity and stable binding. Conclusively, present study provided insight into gene repertoire of genus Anoxybacillus and a basis for the potential application of this thermophile in bioremediation of azo dyes and heavy metals.