Salt-Tolerance Mechanisms of Bacteria and Potential Strategies in Wastewater Treatment

The large amounts of high-salinity wastewater discharged
by industrial
production and other activities restrict the efficiency and stability
of microbial wastewater treatment. Enhancing the salt tolerance of
microorganisms can improve biological saline wastewater treatment
performance and reduce treatment costs. Understanding the salt-tolerance
mechanisms of microbes will improve their widespread application in
treating saline wastewater. The objective of this work was to highlight
the main salt-tolerance mechanisms in microorganisms, including osmotic
regulation and Na+ extrusion, and the related metabolic
pathways. Additionally, the role of extracellular polymeric substances
and halophilic enzymes in salt tolerance was analyzed. Meanwhile,
the mechanistic differences in salt tolerance between halotolerant
and halophilic bacteria were comparatively analyzed, while providing
a critical evaluation of their effectiveness. Strategies to improve
the biological treatment efficiency of high-salinity wastewater, such
as the addition of compatible solutes, genetic engineering of halophilic
orientation for microorganisms, introduction of related proteins,
and modification of biological enzymes, were proposed. These approaches
have significant potential for the improvement of biological treatment
of high-salinity wastewater. By summarizing the salt-tolerance mechanisms
and related potential applications mapped to wastewater treatment,
this article provides effective solutions for faster and more efficient
high-salinity wastewater treatment.