Microplastics in the environment: Interactions with microbes and chemical contaminants

Microplastics (MPs) are contaminants of emerging concern that have gained considerable attention during the last few decades due to their adverse impact on living organisms and the environment. Recent studies have shown their ubiquitous presence in the environment including the atmosphere, soil, and water. Though several reviews have focused on the occurrence of microplastics in different habitats, little attention has been paid to their interaction with biological and chemical pollutants in the environment. This review therefore presents the state of knowledge on the interaction of MPs with chemicals and microbes in different environments. The distribution of MPs, the association of toxic chemicals with MPs, microbial association with MPs and the microbial-induced fate of MPs in the environment are discussed. The biodegradation and bioaccumulation of MPs by and in microbes and its potential impact on the food chain are also reviewed. The mechanisms driving these interactions and how these, in turn, affect living organisms however are not yet fully understood and require further attention.

Nutrient sequestration, biomass production by microalgae and phytoremediation of sewage water

The present work was aimed at analysing the role of inoculated microalgae in nutrient dynamics, bioremediation and biomass production of sewage water. Preliminary microscopic analyses of sewage water revealed the presence of different algal groups, with predominance of Cyanophyta. Among the inoculated strains, Calothrix showed highest dry cell weight (916.67 mg L(-1)), chlorophyll and carotenoid content in tap water + sewage water (1:1) treatment. Significant removal of NO3-N ranging from 57-78% and PO4-P (44-91%) was recorded in microalgae inoculated tap water + sewage water. The total dissolved solids and electrical conductivity of tap water + sewage water after incubation with Calothrix sp. decreased by 28.5 and 28.0%, accompanied by an increase in dissolved oxygen from 4.4 to 6.4 mg L(-1) on the 20th day. Our investigation revealed the robustness of Calothrix sp. in sequestering nutrients (N and P), improving water quality and proliferating in sewage water.

Bioprospecting microalgae as potential sources of "green energy"--challenges and perspectives (review)

Microalgae and cyanobacteria are potential foods, feeds, sources of high-value bioactive molecules and biofuels, and find tremendous applications in bioremediation and agriculture. Although few efforts have been undertaken to index the microalgal germplasm available in terms of lipid content, information on suitability of strains for mass multiplication and advances in development of methods for extraction and generating biofuel are scarce. Our review summarizes the potential of microalgae, latest developments in the field and analyzes the "pitfalls" in oversimplification of their promise in the years to come. Microalgae represent "green gold mines" for generating energy; however, the path to success is long and winding and needs tremendous and concerted efforts from science and industry, besides political will and social acceptance for overcoming the limitations. The major advantages of second generation biofuels based on microalgal systems, include their higher photon conversion efficiency, growth all around the year, even in wastewaters, and production of environment friendly biodegradable biofuels.