Petroleum hydrocarbons bioremediation by halotolerant enzymes - Progress & advances

Oil drilling activities and unintentional oil spills in saline water bodies have resulted in a substantial buildup of oil and its derivatives, leading to a critical environmental problem. Saline water bodies contain a plethora of halophilic microorganisms which show the ability to degrade petroleum hydrocarbons. However, the application of whole cells or designed microorganisms for bioremediation is difficult, because of the harsh conditions. Currently, new methods utilizing halotolerant enzymes are being suggested for cleaning up oil-polluted areas. Halotolerant enzymes exhibit effective functionality even at high salinity levels, making them suitable for degrading diverse hydrocarbons. To make enzymes more efficient and reusable for oil spill cleanup, we need to use biotechnology improvements like immobilization. Thus, the current review provides a general summary of haloenzymes, how they function as biocatalysts, and the challenges and opportunities related to the technologies implemented to clean up hydrocarbons in high-salt content environments. It was identified that there is a high potential for haloenzyme-incorporated technology to be implemented in petroleum hydrocarbon remediation of marine environments due to the higher resistance towards denaturation caused by the presence of high salinity concentration and its extensive metabolic versatility. Furthermore, a wide number of prospects and key challenges faced by haloenzymes in bioremediation were critically discussed. Likewise, this review provides an extensive analysis of the application/use of recombinant haloenzymes; bringing out the lack of understanding of pollutant metabolism under high salt stress conditions and a broad perspective on immobilization and encapsulation strategies that are needed to enhance the enzyme activity and reusability in marine environments.