2.2. Preparation of probiotic cell suspension
A local probiotic referred to as probiotic A was obtained from Dr. Nimrat Laboratory, Burapha University. Probiotic bacteria in the Probiotic A were isolated and identified. Non pathogenic bacteria were found in Probiotic A and Bacillus sp. was the main bacteria in this product. Following the distribution instruction, the probiotic was increased in number by addition of 1 g probiotic to a 500-mL flask containing 200 mL of Trypticase Soy Broth (TSB; Difco, Detroit, MI, USA). The flask was shaken at 200 rpm, and incubated at 30 °C. Cells were harvested by centrifugation after 24 h, prior to suspension in 5 mL of phosphate buffer at an O.D.580 of 1.5. The mixture was freshly prepared and adjusted to a final concentration of approximately 1010 CFU/mL.