Physiological studies of native cyanobacterial species Lyngbya contorta and Phormidium foveolarum in sewage waste water.

A variety of Cyanobacterial species predominantly ensheathed forms occurs in sewage water receiving areas. A study was conducted to analyse the potential of using native Lyngbya contorta and Phormidium foveolarum isolated from sewage water irrigated soils, for biomass production under sewage waste water. The native Cyanobacterial strains were characterised and changes in their biochemical composition in response to different concentrations of sewage waste water were investigated. Results showed that biomass(3.5-6.6 mg 10 ml⁻¹, 2.6-5.6 mg 10 ml⁻¹) and photosynthetic pigment contents increased with incubation time (chlorophyll 1.21-3.09 µg ml⁻¹, 1.92-9.51 µg ml⁻¹; carotenoid 20.8-34.8 µg ml⁻¹, 16.4-32.8 µg ml⁻¹) and decreased thereafter as nutrients became limiting. On the other hand, soluble proteins, after showing a decline, recovered faster with maximum concentration (42.6-63.3 µg ml⁻¹ and 59-79.8 µg ml⁻¹) recorded on day 8. Total carbohydrate content also increased (19.27-31.45 µg ml⁻¹, 14.1-28.21 µg ml⁻¹) in response to various concentrations of sewage waste water. The overall response was better for 50% sewage waste water concentration which showed that these native strains were suitable candidates for cultivation after proper dilution.