The Reaction Of Reactive Oxygen Species (ROS) In Laminaria Japonica Against Infection Of Alginic Acid Decomposing Bacteria

China is one of the major countries which produce marine algae in the world. Among all marine algae, Laminaria japonica is the major cultivating species and its yield is about half of the total marine algae products in the world. However, Rot diseases of Laminaria japonica occurs uaually, especially for the sporelings, and causes huge loss. The occurrence of rot diseases in Laminaria japonica is related to the massive multiplication of alginic acid decomposing bacteria.Five alginic acid decomposing bacteria strains which exhibited highly infective activity were selected as pathogens, and the production and its reaction of reactive oxygen species (ROS) in Laminaria japonica against infection of alginic acid decomposing bacteria were investigated. The results showed as follows:1 .The infection of alginic acid decomposing bacteria resulted in massive production of reactive oxygen species, and the massive production of reactive oxygen species sustained during whole process of infection.2. The production of reactive oxygen species in Laminaria japonica during infection of alginic acid decomposing bacteria was demonstrated universally.3.On early stage of infection by alginic acid decomposing bacteria, the laminaria japonica showed higher antioxidantive activity and higher resistance against infection, and its resistance against infection had positive relationship with productive rate of reactive oxygen species.4. On later stage of infection by alginic acid decomposing bacteria, the antioxidative activity decreased obviously, and the damage of membrane lipid peroxidation and esterification intensified in Laminaria japonica. Meanwhile, the resistance of Laminaria japonica against infection by alginic acid decomposing bacteria notably declined, and its resistance against infection had negative relationship with productive rate of reactive oxygen species.5. On early stage of infection by alginic acid decomposing bacteria, the production of reactive oxygen species played a important role hi resistance against infection of alginic acid decomposing bacteria. On the contrary, the production of reactive oxygen species greatly decreased resistance against infection of alginic acid decomposing bacteria.6. The sustenance of higher antioxidative activity on early stage of infection and sharp decrease of antioxidative activity on later stage of infection by alginic acid decomposing bacteria is one of important reasons which resulted in Contradictory Reaction of Reactive Oxygen Species...