Initial growth responses of the green microalgae Botryosphaerella sudetica (Lemmermann) P.C. Silva and Tetradesmus obliquus (Turpin) M.J. Wynne under varied light intensity, temperature and nutrient conditions

• Main Author: Yunson, Christian Edgar C.
• Format: text
• Language: English
• Published: Animo Repository 2016
• Subjects: Biology
• Online Access: https://animorepository.dlsu.edu.ph/etd_bachelors/18556
• Institution: De La Salle University

This study was carried out to determine the initial growth responses of two green freshwater microalgae that were successfully isolated from Carmona River, Binan, Laguna. These include Botryosphaerella sudetica (Lemmerman) P.C. Silva and Tetradesmus obliquus (Turpin) M.J. Wynne, both potential sources of biofuel and high value bio-products. These microalgae were grown under varied conditions of light intensity (3000, 6000, and 9000 lx), temperature (30°C and 22°C), and culture media (BRSP, TMRL, and Miller & Fogg). Their growth responses in terms of optical densities were monitored for fourteen days on a two-day interval by spectrophotometry at 680 nm & 750 nm for B. sudetica and 750 nm for T. obliquus. Results showed that B. sudetica and T. obliquus exhibited steady growth under all examined conditions. However, significant differences in growth responses were shown by B. sudetica in different culture media, growing best in the more nutrient-deficient TMRL, and by T. obliquus under varied temperatures, growing best at 22°C. B. sudetica exhibited a per cent growth increase close to 3 x 103 (680 nm) and 17 x 103 (750 nm) after 14 days in TMRL under 3000 lx light intensity at 30°C. Percent growth increase in T obliquus was computed to be almost 4 x 102 (750 nm) in TMRL under 9000 lx at 22°C, although initial good growth was generally obtained in all culture media under all light and temperature conditions. Results indicate that B. sudetica can grow initially well in oligotrophic medium at low light intensity and high temperature. T. obliquus strongly demonstrated its ability to grow under wide conditions of light, temperature and nutrient conditions, but attaining initial optimum growth in the combination of low-nutrient, low temperature but high light intensity.