THE GROWTH KINETICS OF Bacillus sp. D2.2 AT DIFFERENT pH AND SALINITY

Abstract

Isolate D2.2 is a bacterial isolate with 97% homology level with Bacillus sp. This isolate is a biocontrol bacterium capable of inhibiting the growth of Gram positive bacteria and Gram negative bacteria. The use of biocontrol bacteria is one solution of disease problem in cultivation organism. Prior to being applied to the field, D2.2 isolates need to go through a series of tests, one of which is growth kinetics testing under various environmental conditions, such as different degrees of pH and salinity. This is because environmental factors can affect the rapid growth of bacteria. The purpose of this study was to study the bacterial growth kinetics of D2.2 at different pH and salinity. The growth kinetics was observed by measuring optical density (OD) through a method of turbidimetry using a spectrophotometer at a wavelength of 625 nm to the stage of death. The results showed that the fastest growth rate was found at 20 ppt salinity with 0.179 h-1 and generation time of 5,588 hours. While in all pH treatments, generation time and growth rates achieved all treatments have the same pattern.

Antagonism Pseudomonas diminuta on The Growth of Vibrio harveyi with Mix Culture Method

“…After that, co-culture was carried out by taking 1 ml of each bacterial culture to grow on TSB media using two bacterial controls, namely V. harveyi control using the resulting LD50 dose of 10 6 CFU/ml (P1) and P. diminuta control with a density 10 5 CFU/ml (P0) which according to Widanarni et al (2003) inoculated probiotic candidate bacteria to be used using a density of 10 5 CFU/ml. In addition, at a density of 10 5 CFU/ml, it is still within the safe limit in water (Hardiyani et al, 2016). After that, it was incubated at 37 o C for 48 hours.…”