Effects Of Temperature On Nitrogen Uptake And Phyllosphere Culturable Bacteria Of Zostera Japonica

Nutrition salt plays an important role in sustaining metabolism of sea grasses.Poor nutrient environment and eutrophic environment have different effects on growth of marine submerged plants.There are differences in the extent of absorption nutrient on different temperature.Phyllosphere microorganisms have important significance on physiological metabolism and ecological function of sea grass.Little is known about the effects of global temperature rising on phyllosphere culturable bacteria of Zostera japonica..The effect of temperature stress on seagrass phyllospheric microorganism bacteria is also investigated.By using the technology of the nitrogen stable isotope tracer,absorption rate changes of Zostera japonica by temperature stress(26?,28?,30 ?and 32?)for four kinds of 15 N nutrient have been studied through indoor experiment simulation of the four temperature level growth environment.And through the gradient heating stress test,the effect of temperature rise on the the cultivation of bacteria to Zostera japonica has been explored by using the isolation and culture of RFLP type,sequencing and phylogenetic analysis methods.The main results are summarized as follows: after different temperature levels on cultured Zostera japonica,the ground and underground parts were conducted four kinds of nitrogen nutrient isotopic absorption experiment.The results showed that:(1)Zostera japonica biomass and morphological indexes were not significant differences at different temperature levels before and after culture.The total biomass,the underground biomass,leaf length,leaf width,stem length,stem diameter,root length in temperature stress after culture showed no significant difference.Only the aboveground biomass index at different temperature levels after training showed significant differences,only at 32? and 26?,30?.(2)?15N‰ values of the ground and underground part of Zostera japonica had significant differences after the experiment of different temperature simulation.After treatment on four nutrient 15 N,on the group part of the Zostera japonica ?15N‰ values was higher than control group,ammonium chloride treatment group was significantly higher than the control group.There was significant difference between 26? and 28?,32?.There was a significant difference between 30? and 28?,32? of ?15N‰ value,indicating Zostera japonica the absorption of ammonium chloride nutrient of the ground part could be seriously affected by temperature change.The urea treatment group ?15N‰ value between 26? and the other three groups are significant difference,between 28? and 30?,32? are significantly different;the underground part of seagrasses ?15N‰ value were higher than the control group,the treatment group of ammonium chloride ?15N‰ value was significantly higher than the control group,between 26? and 28?,30? exist significant differences,there are significant differences between the 32? and 28?,30?,and 28? ?15N‰ value was the highest,32?was the lowest.?15N‰ value of urea treatment group had significant differences between 26?and the other three groups.There are significant differences between the 26? and 28?,30?,there are significant differences between the 28? and 30?,32?,and there are significant differences between 30? and 32?.?15N‰ value of Glu group,there were significantly different between 26? and 28?,32?.28? and 30? were significantly different also,30? and 32? were significantly different.(3)In ammonium chloride treatment group and glutamate treatment group,15 N nutrition absorption rate of ground and underground parts was the highest at 26?.The other three groups had no obvious difference.Nitrate treatment group was the lowest.(4)In four temperature level,ammonium chloride treatment group 15 N nutrient absorption rate on the group part of Zostera japonica was significantly higher than that of Glu group,sodium nitrate treatment group and the urea treatment group.On the underground part of Zostera japonica 15 N nutrient absorption rate,ammonium chloride treatment group and Glu treatment group were higher.Among other two groups,the urea treatment group was higher than sodium nitrate treatment group.(5)The abundance of bacteria increased and then decreased with temperature increasing,but was highest in 32?.A total of 363 strains was isolated,which were divided into 24 OTUs,and no common OTU was found across all temperatures.All strains derived from ? and ?-proteobacteria,and Marinomonas were the most dominant phyla,which accounted for 86.8% of strains in 28?.Pseudomonas and Thalassospira sharply decreased with temperature rising;Marinobacter and Vibrio were enriched in 30?,while Rhodobacteraceae and Ruegeria strongly increased in 32?.The diversities of phyllosphere culturable bacteria were much higher in 26? and 32?,while the lowest was in 28?.