Impact of protozoan Vahlkampfia sp. on the growth of algae Chlorella vulgaris glamtr

Maintenance of high-density microalgal culture forms the basic feature of algal biofuel technology. Algal biomass cultures explore few microalgal species over the other exposing these to grazers, pathogens and predators. So there is an urgent need to explore technologies that will permit early detection and control of these parasites. The present study reports a predatory microbe which hampered Chlorella vulgaris glamtr (Accession no. KX363808.1) biomass productivity. Growth conditions for alga Chlorella vulgaris glamtr were optimized by varying temperature (24-25°C; 27-28°C; 31-32°C), pH (6.4-6.8; 6.8-7.2; 7.2-7.6), light intensity (1900; 2400; 2700 lux) and CO2 concentration (1-5%). Growth kinetics was recorded at 750 nm. Algal biomass was cultivated in RW 1-170P-photobioreactor system and aquarium. The purity of culture was assessed by microscopic examination at 45X. Contaminating protozoan was identified using universal primer (ITS-1 & ITS-4) based amplification of 18S rRNA sequence and its subsequent phylogenetic analysis using MEGA7. Chlorella exhibited optimum growth at 27-28°C, pH 6.8-7.2, light intensity 2700 lux at 5% CO2 concentration. Microscopic examination revealed predatory nature of contaminating protozoan. ITS-based PCR amplification and subsequent phylogenetic analysis revealed the protozoan to be Vahlkampfia sp. Effective subculturing and prevention of protozoan contamination was found to enhance biomass production by 42%. The study reveals that the protozoan Vahlkampfia sp. is a potential predator of microalgae. Prevention of amoebic contaminant and maintenance of optimum environmental conditions could enhance biomass productivity, facilitating algal cultivation.