Resilience and Mitigation Strategies of Cyanobacteria under Ultraviolet Radiation Stress.

Ultraviolet radiation (UVR) tends to damage key cellular machinery. Cells may adapt by developing several defence mechanisms as a response to such damage; otherwise, their destiny is cell death. Since cyanobacteria are primary biotic components and also important biomass producers, any drastic effects caused by UVR may imbalance the entire ecosystem. Cyanobacteria are exposed to UVR in their natural habitats. This exposure can cause oxidative stress which affects cellular morphology and vital processes such as cell growth and differentiation, pigmentation, photosynthesis, nitrogen metabolism, and enzyme activity, as well as alterations in the native structure of biomolecules such as proteins and DNA. The high resilience and several mitigation strategies adopted by a cyanobacterial community in the face of UV stress are attributed to the activation of several photo/dark repair mechanisms, avoidance, scavenging, screening, antioxidant systems, and the biosynthesis of UV photoprotectants, such as mycosporine-like amino acids (MAAs), scytonemin (Scy), carotenoids, and polyamines. This knowledge can be used to develop new strategies for protecting other organisms from the harmful effects of UVR. The review critically reports the latest updates on various resilience and defence mechanisms employed by cyanobacteria to withstand UV-stressed environments. In addition, recent developments in the field of the molecular biology of UV-absorbing compounds such as mycosporine-like amino acids and scytonemin and the possible role of programmed cell death, signal perception, and transduction under UVR stress are discussed.

Purification of Lipase from Pseudomonas aeruginosa VSJK R-9 and Its Application in Combination with the Lipolytic Consortium for Bioremediation of Restaurant Wastewater.

Microorganisms are very important in biodegradation of edible oil contaminated effluents, and they find an excellent scope in restaurant wastewater bioremediation. The edible oil in such wastewater harms the environment in a number of ways. The native bacteria in the wastewater are less effective in degrading edible oil. It leads to the formation of blockage along the sewer line. This narrows the diameter of line and forms partial to complete blockage causing overflows of wastewater exposing humans and animals to diverse pathogens. A consortium of lipolytic bacteria and lipase enzyme gives a new approach for effective and environment friendly degradation of waste oil in restaurant wastewater. In the present study, the lipase produced by Pseudomonas aeruginosa VSJK-R9 isolated from restaurant wastewater was purified by ammonium sulfate precipitation, dialysis and gel exclusion chromatography-Sephadex G-100, with 11.45-fold purification to obtain a yield of 35.08%. Its molecular mass was around 50 kDa as determined by SDS-PAGE analysis. The bioremediation of restaurant wastewater supplemented with 0.5% NH4Cl and 0.8% K2HPO4 was studied with lipolytic consortium formed by the combination of lipolytic isolates Acinetobacter junii VSJK-R6, Pseudomonas composti VSJK-R8 and Pseudomonas aeruginosa VSJK-R9. Further, the impact of lipase supplementation was also evaluated, and it was found that the action of consortium was boosted by lipase. The oil and chemical oxygen demand value of the restaurant wastewater was considerably decreased. These findings have shown the application of lipase for bioremediation of restaurant wastewater and its positive impact on the performance of lipolytic consortium.