The Antialgal Activities And Mechanisms Of Straws To Control The Phaeocystis Globosa Blooms

Objetive: In order to explore the possibility of using straws to control HABs in small scale and provide more information on the screen of algaecides, the effects of finely-chopped straws and aqueous extracts from straws on the growth of Phaeocystis globosa were observed. The roles of microorganism and possible adsorption of chopped straws in the inhibition were assessed. The correlations between total phenol content, chemical composition of extracts and inhibitory activity of straw extracts were analyzed. The changes of algae in morphology induced by straw and aqueous extract were observed by SEM and AFM.Methods: The effect of finely chopped straw on the algae assessed by counting microalga cells under a CKX41 inverted microscope. The role of microorganism was discussed by comparison of inhibitory activity between autoclaved straws and fresh straw. The possible absorption of straws was assessed by the antialgal activity of straws in various sizes and the removal of P. glabosa at different height. The antialgal activities of extracts were evaluated by the fluorescence intensity of cultures. The level of polyphenols in different wood meals was determined by Prussian blue assay. Chemical composition of extracts was identified by GC-MS. Morphological and ultrastructural studies of Phaeocystis globosa were obtained by SEM and AFM.Results: Both finely chopped straws and aqueous extracts of straws exhibited algistatic activities and physical adsorption effects, and microorganisms from straw highly influenced the inhibitory activities of rice straw. There is no direct relation between total phenol content of extracts and the antialgal activities. The algistatic activities and component of extracts under various conditions were different. Except for polyphenols, fatty acids and hydroxide carboxylic acids existed in the extracts inrelatively high content, which played an important role in the algistatic activities. For algae treated with straw or extracts, large changes in morphology was observed by SEMandAFM.Conclusions: Adsorption of straws and antialgal compounds from straws might be responsible for the inhibition, and the latter is more important for the inhibition. Besides polyphenols, fatty acid and hydroxide carboxylic acid might play an important role in the algistatic effect. The straw could damage cell membrane structure, and cause algae cell to die.