Alterations in the Cell Wall of Rhodococcus biphenylivorans Under Norfloxacin Stress

Abstract

Many microorganisms can enter a viable but non-culturable (VBNC) state under various environmental stresses, while they can also resuscitate when the surroundings turn to suitable conditions. Cell walls play a vital role in maintaining cellular integrity and protecting cells from ambient threats. Here, we investigated the alterations in the cell wall of Rhodococcus biphenylivorans TG9 at VBNC state under norfloxacin stress and then at resuscitated state in fresh lysogeny broth medium. Electron microscopy analyses presented that TG9 in the VBNC state had a thicker and rougher cell wall than that in exponential phase or resuscitated state. Meanwhile, the results from infrared spectroscopy also showed that its VBNC state has different peptidoglycan structures in the cell wall. Moreover, in the VBNC cells the gene expressions related to cell wall synthesis and remodeling maintain a relatively high level. It indicates that the morphological variations of TG9 at the VBNC state might result from kinetic changes in the cell wall synthesis and remodeling. As a consequence, the alterations in the cell wall of VBNC TG9 may somewhat account for its tolerance mechanisms to antibiotic treatment.

Human gut-derived B. longum subsp. longum strains protect against aging in a d-galactose-induced aging mouse model

“…For example, significant SNP variations in cell wall biosynthesis-related genes and biofilm formation pathway in the core genomes of different B. longum populations might be a reflection of different degree of antibiotic exposure among subjects from different countries. Antibiotic stress has been reported to be able to induce bacterial biofilm formation [ 73 ] and alter expression of their cell wall biosynthesis-related genes [ 74 ]. Meanwhile, it has been confirmed that deletion of bacterial genes involved in cell wall biosynthesis [ 75 ] or overexpression bacterial genes that influence biofilm formation [ 76 ] led to significant changes of bacterial resistance against specific antibiotics.…”

Responses to Ecopollutants and Pathogenization Risks of Saprotrophic Rhodococcus Species

“…Third, the increased cell roughness is a result of extracellular polymer secretion and changes in the lipid composition of the cell wall, which increases the Van der Waals forces, and thus promoting better adhesion of cells to each other and to substrates [ 146 ]. The study of viable but nonculturable R. biphenylivorans T9 cells in the presence of the antibiotic norfloxacin revealed an increase in the cell wall roughness proportional to the increase in biofilm formation [ 147 ].…”

Rhodococcus strains as a good biotool for neutralizing pharmaceutical pollutants and obtaining therapeutically valuable products: Through the past into the future

“…Rhodococci are known for a set of antibiotic resistance mechanisms, whether efflux pumps, antibiotic-resistance genes encoding drug/metabolite transporters, beta-lactamase related proteins, penicillin-binding proteins, proteins involved in folate biosynthesis, and unique cell wall containing α-alkyl-β-hydroxy fatty acids named mycolic acids ( de Carvalho et al, 2014 ; Orro et al, 2015 ; Jia et al, 2020b ). Moreover, when exposed to antibiotics, Rhodococcus spp.…”

“…Thus, for example, norfloxacin-exposed rhodococci entered the dormant state accompanied by a thickened cell wall and an increased roughness at the morphometric level. While at the metabolic and functional levels, errors during DNA replication, subsequent homologous DNA repair (as evidenced by the increased content of repair proteins RecA, uvrA, UvrB, and UvrC in dormant forms), suppression of transporter proteins, ATP production, and the tricarboxylic acid cycle were observed ( Jia et al, 2020b ; Yu et al, 2022a ). Given the simultaneous presence of many pollutants in the environment, bacterial adaptation to antibiotics reduces the degradation efficiency of other priority pollutants.…”