ABSTRACT
This work aimed to obtain an ideal mutant strain with higher lipase yield using hydrazine hydrate (HZH) as a novel additive to treat Flavobacterium sp. strain YY25 by supercritical CO2. The survival rate and the positive mutation rate of the tested strain were strongly dependent on the dose of HZH. The treatment by 0.5% HZH in supercritical CO2 (8 MPa, 35°C) for 30 min provided 58.3% of positive mutation rate and an expected mutant strain with about 76.7% increase in lipase yield compared with the wild strain. Possible mutagenesis mechanisms were further explored. The analysis on pH drop of the treated seed liquid was performed to better understand the interaction. Results proved that the induced mutation with enhanced yield of lipase could be achieved by co-mutagenesis of supercritical CO2 and HZH.
ABSTRACT
Objective To study on algicidal bioactive substances from mangrove bacteria and its algicidal effect on red tide algae Alexandriam tamarense.Methods A red algicidal bioactive substance in Guangxi mangrove bacteria was isolated and purified by Silica-gel Column Chromatography,and its structure was determined on the basis of UV,IR,1H NMR,13C NMR and HREIMS spectroscopic analyses and comparison with the literatures.Its algicidal affect was primarily studied in this paper.Results and Conelusion The results showed that the red algicidal bioactive substance was prodigiosin,which had an inhibitory effect on the cells growth of Alexandrium tamarense,and the inhibitory effect increased with the increase of prodigiosin concentration.The prodigiosin stimulated the production of MDA and reduced the content of sulfhydryl group.In addition,plasma membrane permeability of leaked cell solution was increased.These indicated the extinguishing mechanism: the cell membrane was damaged followed by the inhibition of the cell growth.