Biodegradation of malodorous mercaptans by a novel Staphylococcus capitis strain isolated from gas-washing wastewaters of the Tunisian Chemical Group

Abstract

There are increasing concerns over the harmful effects of the phosphate industry on human health and quality of life worldwide, including the Tunisian Chemical Group (GCT) in Sfax, which generates various malodorous gas fractions, such as hydrogen sulfide (H 2 S) and fetid mercaptans, causing nuisance to employees and local residents. Accordingly, the present study aimed to investigate the ability of an adapted microbial consortium isolated from the gas-washing wastewaters (GWWs) generated from GCT to degrade hazardous and malodorous mercaptans. A novel mesophilic bacterial strain (SH6), which was noted to display particularly high mercaptan degradation potential, was isolated from the adapted consortium growing on those GWWs and several malodorous mercaptans after enrichment on 1-dodecanethiol. The results from 16 rRNA gene sequencing and identity analysis revealed that the SH6 isolate belonged to Staphylococcus genus, with a high sequence similarity to Staphylococcus capitis (99.7 %). The SH6 strain was able to completely degrade 1-dodecanethiol, used as the sole carbon and energy source, after 72 h of incubation at 37°C and 180 rpm. A decrease in the surface tension of cell-free culture supernatants was observed during the oxidation of dodecanethiol, suggesting the production of surface-active compounds. The stain was also able to grow on other mercaptans, such as 1,8-octanedithiol and 2,3-butanedithiol, which further supports its potential candidacy for application in the bioremediation of mercaptan-contaminated sites. Overall, the findings of the present study indicate that the SH6 strain might offer promising opportunities for the development of more adapted, efficient and cost-effective bio-disodoration strategies.

Purification and biochemical characterization of an organic solvent‐tolerant and detergent‐stable lipase from Staphylococcus capitis

“…The strain is a non‐spore‐forming, nonmotile, and aerobic. It is a mesophilic bacterium that grows at 25–55°C and pH 5–10, where it can grow optimally in neutral media . It is a halotolerant strain that grew optimally with or without NaCl.…”

“…It was identified by morphological, physiological, chemotaxonomic, and molecular assays as reported by Chebbi et al 18 The 16S ribosomal RNA gene sequencing, (c. 1452 b) was determined and deposited in the GenBank nucleotide database under accession number KP455742. 18 Lipase producing bacteria was carried out by plating 1% olive oil, 0.1% rhodamin B, 2 mM CaCl 2 , 1 mM NaTDC on LB agar plates containing: 1% tryptone, 0.5% yeast extract, 1% NaCl, and 1.8% agar, pH 7. After incubation overnight at 37 C of the culture plates, the lipolytic activity was confirmed by the observation of a clear zone around the colony.…”

Promising abilities of mercapto‐degrading Staphylococcus capitis strain SH6 in both crude oil and waste motor oil as sole carbon and energy sources: its biosurfactant production and preliminary characterization

“…olive oil) have been shown to be effective in biosurfactant synthesis, such as the case of biosurfactants produced by Pseudomonas sp. W10 . A probable reason for this tendency is that Staphycocclocus spp.…”

“…During the growth of strain C450R on crude oil, the emulsifying activity (E24) and glycoside content increased and reached values of 77% and 1.33 g L ‐1 , respectively . However, polycyclic aromatic hydrocarbons, such as pyrene, fluoranthene, phenanthrene and naphthalene, are recognized to be highly toxic for bacterial cells …”

“…Strain SH6 was capable of degrading dodecanethiol, used as the sole source of carbon and energy. The reduction of surface tension was also observed suggesting the production of surface‐active compound(s) or biosurfactant(s) . To the best of our knowledge, no studies have been reported on Staphylococcus capitis species for hydrocarbon degradation and biosurfactant production.…”