Comparative physiological response of filamentous cyanobacteria Phormidium tenue and Leptolyngbya lignicola under chromium (VI) stress

Abstract

AbstractNumerous technologies for cleaning the environment without producing hazardous waste products have arisen in response to the rise in environmental pollution. Industrialization and the growing population have put society to a hard test. Continuous discharge of heavy metals (chromium, nickel, copper, mercury etc.) in water bodies is increasing by anthropogenic activities; these cause bio accumulation and shift towards a resistant microbial community. These hazardous metals enter the human body through water and food, creating a slew of health issues. Chromium (VI) is one such toxic pollutant and is more toxic than chromium (III). Several environment‐friendly technologies have been developed for decontaminating wastewater by using microorganisms. Microalgae, cyanobacteria, bacteria and fungi are used for heavy metals eradication from the water due to their metal tolerance, bioaccumulation and biotransformation capacity. In this study two cyanobacteria strains were compared for their physiological response and metal tolerance for Cr (VI) stress. Leptolyngbya lignicola and Phormidium tenue were grown in a medium containing various concentrations of chromium (1 ppm, 2 ppm, 3 ppm, 4 ppm, 5 ppm, and 10 ppm), and biochemical parameters (chlorophyll, carotenoids, protein, proline, amino acid, carbohydrate, reducing sugar and lipid content) were measured. The findings revealed that P. tenue was more sensitive to metal stress than L. lignicola. P. tenue showed a decreasing trend for all biochemical parameters except proline at higher ad lower doses of Cr (VI) stress. However L. lignicola showed an increase in biomass (6.09%) and other biochemical parameters over control at lower metal stress concentration (1 ppm), whereas, a gradual decrease in all parameters except proline was observed at higher concentrations. Further L. lignicola showing high tolerance index can be preferred for metal remediation from the water bodies of heavy metal contaminated area.