Background: Alginate lyase is known to have antibiofilm activity. Toxicity tests for the alginate lyase produced by Streptomyces olivaceus from Serena Kecil Island, North Sulawesi, Indonesia, have never been reported. This research conducted an in vivo toxicity study of the alginate lyase, using male Wistar rats for its development as an oral anti-biofilm agent.
Methods: Twenty male Wistar rats (Rattus norvegicus) were divided equally into four groups of: technical control (TC), which was only given food and drink; negative control (NC), given phosphate buffer saline 1x; experimental group (E1), given alginate lyase at a dose of 0.63 g/kg BW, and (E2), given alginate lyase at a dose of 20.85 g/kg BW. The toxicity tests were carried out for 7 days by observing the following parameters: changes in the body weight and behavior; changes in AST and ALT enzyme levels; and evaluation of macroscopic and microscopic damages to the liver.
Results: After 7 days of treatment, rats in the NC, E1, and E2 groups experienced insignificant weight losses. They also had normal behavior and did not show signs of toxicity or death. The AST and ALT levels in rats, given alginate lyase (E1 and E2) decreased significantly but were still within the normal range.  Alginate lyase also caused an adaptive stress response and degeneration in the liver cells.
Conclusion: Alginate lyase at 0.63 g/kg BW and 20.85 g/kg BW were considered safe in the rats and had the prospect of being developed into an anti-biofilm agent.