Antibacterial Activity of Faloak (<i>Sterculia quadrifida</i> R.Br.) Bark Extract in Inhibiting <i>Streptococcus agalactiae</i> Bacteria Isolated from Mastitis Cow’s Milk

Abstract Mastitis is an infection of the mammary glands of dairy cows caused by bacteria. It can reduce milk yield and quality. This research aimed to determine the antibacterial ability of faloak bark in inhibiting Streptococcus agalactiae isolated from mastitis cow’s milk. Bacterial isolation was performed on milk from cows infected with mastitis. Successfully isolated bacterial isolates were tested by Gram stain, haemolytic test, catalase test, motility test, and PCR to confirm that the bacteria were Streptococcus agalactiae . In vitro antibacterial test using disk diffusion method with treatment of faloak bark extract compared with commercial antibacterials and distilled water. The data analysis used was Analysis of variance and Duncan multiple range test. After obtaining Streptococcus agalactiae isolates, the isolates were rejuvenated and then tested for antibacterial activity in vitro. Streptococcus agalactiae could be inhibited by faloak bark extract. The 5% concentration of faloak bark extract had the same ability as commercial antibacterials. The higher the concentration of faloak bark extract, the larger the diameter of the inhibition zone produced.