ABSTRACT

This work investigated the growth characteristics of six yeast strains isolated from palm wine and were subjected to aerobic and anaerobic condition at different temperatures of 20°C, 25°C, 30°C, 35°C and 40°c. They were also exposed to osmotic stress using 5%, 10%, 15%, 20% and 25% concentrations of NaCi, CuSO4and Na2S204solutions. A viability measurement of the yeast strains was earned out to determine the viable and non viable strains after they had been subjected to stress using slide culture and methylene blue technique. The results obtained showed that growth was obtained showed that growth was rapid during aerobic condition for all the temperature and decline under anaerobic condition where scanty growth was observed at 20°C and 25°C while at 30°C, 25°C and 40°C, there was no growth. The result obtained during exposure to osmotic stress showed that at 5% NaCI all the six yeast strains had scanty growth while at higher concentration of same solution there was no growth. NaS2O4treatment resulted in scanty growth at 5% concentration while at higher concentration there was no growth. CuSO4treatment had no growth at any of the concentrations used (between 5-25%). The results of viability measurement showed that the strains which had growth produced micro colonies on the slide culture and did not strained blue with methylene blue. Conclusively, the result of this work indicate that osmotic and thermic stress are two main adverse conditions that could hamper the growth performance of yeast strains under laboratory and industrial processes.