Heavy metal and pesticide pollution have become an inevitable part of the modern industrialized environment that find their way into all ecosystems. Because of their persistent nature, recalcitrance, high toxicity and biological enrichment, metal and pesticide pollution has threatened the stability of the environment as well as the health of living beings. Due to the environmental persistence of heavy metals and pesticides, they get accumulated in the environs and consequently lead to food chain contamination. Therefore, remediation of heavy metals and pesticide contaminations needs to be addressed as a high priority. Various physico-chemical approaches have been employed for this purpose, but they have significant drawbacks such as high expenses, high labor, alteration in soil properties, disruption of native soil microflora and generation of toxic by-products. Researchers worldwide are focusing on bioremediation strategies to overcome this multifaceted problem, i.e., the removal, immobilization and detoxification of pesticides and heavy metals, in the most efficient and cost-effective ways. For a period of millions of evolutionary years, microorganisms have become resistant to intoxicants and have developed the capability to remediate heavy metal ions and pesticides, and as a result, they have helped in the restoration of the natural state of degraded environs with long term environmental benefits. Keeping in view the environmental and health concerns imposed by heavy metals and pesticides in our society, we aimed to present a generalized picture of the bioremediation capacity of microorganisms. We explore the use of bacteria, fungi, algae and genetically engineered microbes for the remediation of both metals and pesticides. This review summarizes the major detoxification pathways and bioremediation technologies; in addition to that, a brief account is given of molecular approaches such as systemic biology, gene editing and omics that have enhanced the bioremediation process and widened its microbiological techniques toward the remediation of heavy metals and pesticides.

Basmati rice is in high demand in the world market because of its fine, soft, long and distinctive aromatic grains. Bacterial leaf blight (BLB), caused by Xanthomonas oryzae pv. oryzae, is a destructive disease, resulting in enormous yield loss in basmati rice. Chemical management against BLB is effective but not the preferred approach because of its detrimental effects on humans, environment and ecological disruption. In the present study, seed treatment, seedling treatment and foliar application with microbial antagonists, such as Trichoderma harzianum and Pseudomonas fluorescens, and a consortium encompassing both microorganisms plus Trichoderma asperellum, were assessed against BLB in basmati rice. Among all the bio-formulation treatments, seed treatment with the microbial consortium revealed significant (p<0.05) results, achieving maximum inhibition of BLB incidence, intensity and lesion length of 48.56, 52.42 and 45.41 percent respectively, compared to the untreated control. Simultaneously, the same treatment also resulted in significant (p<0.05) enhancement of growth attributes, such as panicle length (55.83%), plant fresh weight (15.55%), grains per panicle (38.23%), test weight (55.49%) and yield (47.68%). A maximum increase in superoxide dismutase and hydrogen peroxide activities by 81.58 and 84.29 percent respectively over the control was also recorded. The results of the study suggest that the effectiveness of BLB management under field conditions applying the microbial consortium (T. harzianum+T. asperellum+P. fluorescens) was similar to that of the chemical control. Further, efforts are being made to evaluate the biocontrol activity of the microbial consortium in large-scale field experiments and its commercial potential.

Trichoderma has been found to have effectiveness against a vast range of plant diseases and can be a good alternative biocontrol strategy in the modern era of plant disease management. It has been found effective against soil borne pathogens and nematodes. Trichoderma has been isolated from variable soils and has multifaceted application other than disease management. Trichoderma enhances plant growth and development by boosting the plants capacity to absorb nutrients, increasing systemic resistance to pest and/or pathogen attacks in the future, increasing tolerance to abiotic stresses (such as salinity, drought, and low temperatures). For instance, the stress on organic management in the modern cropping system, Trichoderma is a promising soil enhancer and can have handful applicability for diseases particularly those of soil borne ones. Its competitive mechanism and antagonistic approaches to compete with other pathogens makes it a good fit for future crop management strategies.