Bacterial Genetic Bioaugmentation in the Bioremediation of Soil Pollutants: A Mini Review

Abstract

The rate of pollution due to population growth and anthropogenic activities has become a threat to the global environment, food security, and public health safety. This is why soil health was the main emphasis at the FAO science policy symposium on ‘Soil and Water: A Source of Life’ (GSOWA23) held in October 2023. Advocacy for strategies to preserve the soil’s ecological services to different life forms and its healthy conservation for resolving global food security challenges is now attracting research interest. Soil health has become a component in management, socioeconomic, and political studies. Hence, bioaugmentation proved to be a safe bioremediation technique that is constantly improved by enrichment with selected nonindigenous strains of pollutant-scavenging microbes, nutrients, and gene factors to restore polluted soils to their natural state. The unpredictable influence of climate factors may limit the field application of enrichment bioaugmentation techniques leading to the recent paradigm shift to genetic bioaugmentation for more stable outcomes. This influence may impact bacterial viability, abundance, and dispersal in the soil matrix after the inoculation of a virile non-indigenous bioremediant. Genetic limitations of indigenous soil bacteria with weak degradative potential might be surmounted by genetic bioaugmentation. Therefore, genetic bioaugmentation introduces genetically engineered microorganisms (GEM), and non-indigenous bacteria with the innate virility to fix target pollutants into an ecosystem to improve the biological process. Weak degradative indigenous bacteria in polluted soils are bio-augmented through exposure to degradative genes of other nonindigenous microorganisms, loose plasmids, and mutagens to boost viability, proliferation, and environmental stress resilience responses. These genes, which may be specific or broad-action degradative genes spread through the soil biomass by horizontal gene transfer. Therefore, this review studied the biological agents popular in genetic bioremediation, mobile elements used in the horizontal gene transfer among bacteria, and the limitations of the bioaugmentation process. It also aims to identify research gaps, project future direction in the improvement of genetic bioaugmentation, and suggest solutions to the limitations of the process.