Manganese Stress Adaptation Mechanisms of Bacillus safensis Strain ST7 From Mine Soil

Abstract

The mechanism of bacterial adaption to manganese-polluted environments was explored using 50 manganese-tolerant strains of bacteria isolated from soil of the largest manganese mine in China. Efficiency of manganese removal by the isolated strains was investigated using atomic absorption spectrophotometry. Bacillus safensis strain ST7 was the most effective manganese-oxidizing bacteria among the tested isolates, achieving up to 82% removal at a Mn(II) concentration of 2,200 mg/L. Bacteria-mediated manganese oxide precipitates and high motility were observed, and the growth of strain ST7 was inhibited while its biofilm formation was promoted by the presence of Mn(II). In addition, strain ST7 could grow in the presence of high concentrations of Al(III), Cr(VI), and Fe(III). Genome-wide analysis of the gene expression profile of strain ST7 using the RNA-seq method revealed that 2,580 genes were differently expressed under Mn(II) exposure, and there were more downregulated genes (n = 2,021) than upregulated genes (n = 559) induced by Mn stress. KAAS analysis indicated that these differently expressed genes were mainly enriched in material metabolisms, cellular processes, organism systems, and genetic and environmental information processing pathways. A total of twenty-six genes from the transcriptome of strain ST7 were involved in lignocellulosic degradation. Furthermore, after 15 genes were knocked out by homologous recombination technology, it was observed that the transporters, multicopper oxidase, and proteins involved in sporulation and flagellogenesis contributed to the removal of Mn(II) in strain ST7. In summary, B. safensis ST7 adapted to Mn exposure by changing its metabolism, upregulating cation transporters, inhibiting sporulation and flagellogenesis, and activating an alternative stress-related sigB pathway. This bacterial strain could potentially be used to restore soil polluted by multiple heavy metals and is a candidate to support the consolidated bioprocessing community.

Biofilm Formation by Mutant Strains of Bacilli under Different Stress Conditions

“…There is evidence that the exogenous presence of Mn 2+ ions promotes the formation of stable biofilms in bacilli by participating in the activation of phosphorel, which is necessary for phosphorylation of the global transcription factor Spo0A, presumably acting as a signaling cofactor with histidine kinase KinD and protein components of phosphorele, Spo0F and Spo0B phosphotransferases [ 28 ]. The effect of manganese ion stimulation on biofilm formation has been found for many bacilli and suggests that this signaling pathway for biofilm formation is highly conserved for this group of microorganisms [ 29 , 30 ].…”

Caracterização de bactérias resistentes a metais pesados e o potencial para biorremediação

“…Tal característica metabólica aponta a versatilidade e adaptabilidade desses microrganismos frente a agentes poluentes e contaminantes. ativo (Ran et al, 2021). Nies (1999) relata que a tolerância observada às altas concentrações de Mn pode ser atribuída à menor toxicidade deste elemento.…”

“…Outros estudos têm mostrado microrganismos com alta tolerância ao Mn, sendo importantes em oxidar e adsorver o Mn (II), podendo, alguns microrganismos, ser capazes em produzir ácido indolacético, sideróforos e potencial de solubilização de fósforo (Yan et al, 2014;Xu et al, 2019), colaborando no crescimento de plantas. Ran et al (2021) mostraram que a cepa ST7 de Bacillus safensis se adaptou à exposição ao Mn alterando o metabolismo, regulando os transportes de cátions, inibindo a esporulação e a flagelonêse e ativando uma via relacionada ao estresse (sistema sigB).…”

“…Importância -Atividade antimicrobiana; resistente a antibióticos; Wu et al, 2021;Domingos et al, 2015;Rong et al, 2020;Defalco et al, 2021;Romero-Severson et al, 2021;da Fonseca et al, 2015;Thite et al, 2020;Strahsburguer et al 2019;Chakraborty et al, 2013;Satomi et al, 2006;Ran et al, 2021 Habitat -Superfícies de naves espaciais; solos com metais pesados e salino; campos petróleo; plantas; deserto; estuário;…”

“…Observa-se que o gênero Bacillus possui diversas aplicações por apresentar resistência a metais pesados, pesticidas e antibióticos, atuarem como promotor de crescimentos de plantas e ter ação antifúngica e viral contra patógenos de interesse na agricultura (como referenciado na tabela 4). Muitas espécie de Bacillus, como B. safensis (Ran et al, 2021), B.…”