Olusola-Makinde, Olubukola Olayemi; Bayode, Michael Tosin, and Somefun, Ayomikun Christian
Virulence is the extent of pathogenicity displayed by majority of pathogens and yardstick that efficiently distinguishes pathogenic and non-pathogenic organisms. Effects of pH, temperature and incubation period were studied on capsule-positive bacteria isolated from Onyearugbulem stream, Akure. The molecularly identified bacteria were tested for haemolysis using blood agar (5% v/v) and for the presence of capsule using India ink. ß-haemolytic bacteria were subjected to different temperature (15 °C – 60 °C) and pH (6.0 – 9.0) ranges. pH conditions were achieved by the addition of 0.01M NaOH and 0.01M HCl to media before sterilization. The zones of clearance (mm) were measured at 24 h, 48 h and 72 h. Proteus penneri showed the highest haemolytic activity (56mm) at 28 °C after a duration of 72 h. Bacillus cereus showed the highest haemolytic activity (52mm) at pH 8.5, after 72h Dye degradation was optimum at 10 to 12 h at 37 °C which showed the haemolytic bacterial organisms were capsule-positive. The findings in this study revealed that bacteria present in Onyearugbulem stream contained virulent factors with highest activity at ambient temperature (28 °C) which indicate the poor quality of the stream and thereby constitute serious health threat to man and animals.
