Growth pattern of Bacillus sp. (NrLtF5) isolated from the gastrointestinal tract of the nypa worm (Namalycatis rhodochorde) at different pH and salinity values
By: Ari Hepi Yanti, Eka Karunia, Rikhsan Kurniatuhadi, Tri Rima Setyawati, Novik Nurhidayat
Bacterial isolates of the genus Bacillus (code NrLtF5) have been isolated from the gastrointestinal tract of nypa worms (Namalycastis rhodochorde). This isolate is known to have probiotic potential and is cellulolytic, so it can be developed in nypa worm feed formulas. This study aims to determine the optimal salinity and pH for the growth of Bacillus sp. (NrLtF5). Salinity and pH are environmental factors that affect microbial growth, so optimization is necessary to obtain optimum values for cell production. The research was conducted using a microplate shaker culture method on Glucose Yeast Peptone (GYP) medium. The treatment of pH values was adjusted by the addition of 5M NaOH and 5M HCl to obtain pH values of 4, 5, 6, and 7, while the salinity value was adjusted by adding NaCl to media with salinity values of 5%, 10%, and 15%. Measurement of the growth pattern of Bacillus on salinity and pH values used the response surface methodology (RSM) with the central composite design (CCD) method at a wavelength of 585 nm. The results showed that the optimum growth value of Bacillus sp. (NrLtF5) was at a salinity of 15% with a pH value of 6. This is closely related to the growth character of nypa worm and has the potential to be developed as a probiotic for nypa worm culture.