Glycine betaine enhances biodegradation of phenol in high saline environments by the halophilic strainOceanobacillussp. PT-20

Abstract

The halophilic bacterial strain PT-20, isolated from saline alkali soil samples and identified as a member of the genus Oceanobacillus, exhibited a robust ability to degrade phenol under high salt conditions. It was determined that strain PT-20 was capable of degrading 1000 mg L À1 phenol completely in the presence of 10% NaCl within 120 h. Under the optimal degradation conditions, pH 8.0, 3% NaCl and 30 C, 1000 mg L À1 phenol could be completely degraded in 48 h. Interestingly, the biodegradation rate of phenol was dramatically improved in the presence of glycine betaine. When glycine betaine was added, the time required to degrade 1000 mg L À1 phenol completely was significantly reduced from 120 h to 72 h, and the corresponding average degradation rate increased from 8.43 to 14.28 mg L À1 h À1 with 10% NaCl. Furthermore, transcriptome analysis was performed to investigate the effects of phenol and glycine betaine on the transcriptional levels of strain PT-20. The results indicated that the addition of glycine betaine enhanced the resistance of cells to phenol, increased the growth rate of strain PT-20 and upregulated the expression of related enzyme genes. In addition, the results of enzyme activity assays indicated that strain PT-20 degraded phenol mainly through a meta-fission pathway.

A study of highly efficient phenol biodegradation by a versatile Bacillus cereus ZWB3 on aerobic condition

“…At neutral or slightly alkaline environment, the degraded efficiency is high, especially at pH 9. Compared with the reported strains (Wu et al 2018;Long et al 2019;Lee et al 2020), the degraded pH range of strain ZWB3 is wider, which can better adapt to the change of acid and alkali environment, while the degradation efficiency under neutral and slightly alkaline conditions is better. The reason is that phenol is transformed to organic acids through ring opening in the process of microbial degradation, which leads to the decrease of pH in the environment.…”

“…In addition to phenol, the industrial wastewater often contains phenol derivatives and heavy metal ions, which bring great challenge for efficient biodegradation associated with tolerance of microorganisms in the harsh environment. At present, most microbial degradation of phenol concentration range of about 1,000-1,200 mg/L, and the time required for complete degradation ranges from about 32-75 h (Shahryari et al 2018; Gomes e Silva et al 2019;Long et al 2019;Nouri et al 2020;Wen et al 2020;Gong et al 2021). Therefore, many known phenol degrading microorganisms still have limitations in biodegradation ability and rate.…”

Comparing transcriptome expression profiles to reveal the mechanisms of salt tolerance and exogenous glycine betaine mitigation in maize seedlings

“…Under 10% NaCl, PT-20 completely degrades 1000 mg�L -1 phenol within 120 h. After adding GB, the time was shortened to 72 h, and the corresponding average degradation rate was increased from 8.43 to 14.28 mg�L -1 �h -1 . The results of transcriptome analysis showed that the addition of GB enhanced the resistance of cells to phenol; furthermore, GB increased the growth rate of strain PT-20 and up-regulated the expression of related enzyme genes [20]. Although researchers have conducted many studies on the effect of exogenous GB on plant responses to stress, there have been few transcriptome studies aimed at revealing the mechanism by which GB mitigates the effects of salt stress in maize.…”