Isolation and characterization of Streptococcus agalactiae inducing mass mortalities in cultured Nile tilapia (Oreochromis niloticus) with trials for disease control using zinc oxide nanoparticles and ethanolic leaf extracts of some medicinal plants.

Background: Streptococcus agalactiae (Group B streptococcus, GBS) induces a serious infection that can harm not only aquatic life but also humans and other animals. In a fish farm in southern Egypt, Nile tilapia (Oreochromis niloticus) has developed an epidemic with clinical symptoms resembling piscine streptococcosis.

Results: Initial microscopic inspection of the affected fish brain and kidney indicated the presence of Gram-positive cocci.

Antioxidant lipoxygenase inhibitors from the leaf extracts of Simmondsia chinensis.

Objective: To isolate and identify chemical constituents with antioxidant and lipoxygenase inhibitory effects of the ethanolic extract of Simmondsia chinensis (Jojoba) leaves.

Methods: The alcoholic extract was subjected to successive solvent fractionation. The antioxidant active fractions (chloroform, ethyl acetate and aqueous fractions) were subjected to a combination of different chromatographic techniques guided by the antioxidant assay with DPPH.