Antioxidant, antibacterial, and anti-adhesive activities of biosurfactants isolated from Bacillus strains.

Biosurfactants are surface-active compounds that display a range of physiological functions. The present study investigated the antioxidant, antimicrobial, and anti-adhesive or anti-biofilm potential of biosurfactants isolated from Bacillus subtilis VSG4 and Bacillus licheniformis VS16. The antioxidant activity of the biosurfactants was studied in vitro using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radicals. At 5 mg/mL of the biosurfactant concentration, the scavenging of DPPH and hydroxyl radicals was found to be between 69.1-73.5% and 63.3-69.8%, respectively. The biosurfactants also displayed significant antibacterial activities against both Gram-positive and Gram-negative bacteria. The anti-adhesive activities of the biosurfactants were evaluated against Staphylococcus aureus ATCC 29523, Salmonella typhimurium ATCC 19430, and Bacillus cereus ATCC 11778. The biosurfactants exhibited anti-adhesive activity, even at concentrations of 3-5 mg/mL. Moreover, both biosurfactants displayed notable anti-biofilm activities with a biofilm eradication percentage ranging from 63.9 to 80.03% for VSG4 biosurfactant, and from 61.1-68.4% for VS16 biosurfactant. Furthermore, VSG4 biosurfactant exhibited emulsification and surface tension stability over a wide range of pH (4-10) and temperature up to 100 °C. These results show that VSG4 and VS16 biosurfactants can be potentially used as natural antioxidants, antimicrobials, and/or anti-adhesive agents for food and biomedical applications.

Effect of Ovaprim doses and latency periods on induced spawning of Clarias batrachus: observation on larval deformity.

Induced spawning of C. batrachus was conducted at different Ovaprim dose and latency period combinations to observe the deformed larvae among the hatchlings. For the purpose, four doses of Ovaprim (0.5, 1.0, 1.5 and 2.0 ml/kg body weight) and five latency periods (11, 14, 17, 20 and 23 hr) were considered in 20 different combinations. There were no deformed larvae in the females injected with all four doses and stripped at 11 hr latency, as the eggs did not hatch. The percentage of deformed larvae (4-7%) did not vary significantly at 1.0-2.0 ml dose level in combination with 14-17 hr latency periods. While increasing the latency period beyond 17 hr at 1-1.5 ml dose level, the percentage of deformed larvae increased significantly and touched as high as 11%. The results indicated that 1-1.5 ml dose in combination with 14-17 hr latency are suitable to reduce the deformed larvae among the hatchlings during induced spawning of C. batrachus.

Seminoma in hybrid catfish [Clarias batrachus (Linnaeus) female x Clarias gariepinus (Burchell) male].

Spontaneous testicular tumors, seminoma, were noticed in four male hybrid catfish (C. batrachus female x C. gariepinus male) after the age of two years. The hybrids showed massive abdominal swelling with catchectic body and free lobulated, encapsulated tumors (> 325 g) within the serosanguinous fluid-filled peritoneal cavities. The tumor cells were large and polyhedral with prominent centrally located nuclei. Other vital organs appeared normal. It seems to be the first report of seminoma in hybrid catfish and possibly of genetic cause.