Study On The Growth Inhibition Of Cyanobacteria By The Bacteria From Eutrophic Water After Being Enhanced By Photosynthetic Bacteria

At present,the eutrophication of water bodies is becoming more and more serious,and the problem of cyanobacteria blooms is endless.In aquaculture,the photosynthetic bacteria are used to inhibit algal blooms.However,it is found that the photosynthetic bacteria itself has no obvious effect on algae inhibition.There are many bacteria with algae-reducing potential in eutrophic water.This paper conjectures and studies that photosynthetic bacteria indirectly control cyanobacterial blooms by enhancing the algae-inhibiting effect of eutrophic water bacteria.This study investigated the algicidal effect of photosynthetic bacteria in the presence or absence of eutrophic water bacteria,isolated eutrophic water bacteria and explored the phenomenon that photosynthetic bacteria can enhance the inhibition of algae with bacteria from the eutrophic water.The main contents and results of this study are as follows:1.One photosynthetic bacteria PSB-JS was screened and purified,and 16S rDNA sequencing and strain phylogenetic tree indicated that they are homologous to Rhodopseudomonas faecalis.2.Rhodopseudomonas JS had no significant effect on the growth of cyanobacteria algae at a final concentration of 10~6 CFU/mL.When the Anabaena cylindrica contains natural eutrophic water bacteria,the same addition of photosynthetic bacteria can reach 65.41%algae inhibition rate after 6 days,indicating that photosynthetic bacteria may have a certain coupling effect to inhibit the growth of Anabaena combined with bacteria in natural eutrophic water.3.38 strains of bacteria were isolated from eutrophic water,and combined with photosynthetic bacteria Rhodopseudomonas JS to do experiment which inhibit Anabaena cylindrica.One of them had great algae-inhibiting effect,and 5 strains could be enhanced by photosynthetic bacteria to inhibit Anabaena cylindrica.Finally,a strain Pseudomonas AB-31was chosen because the effect is most obvious.The inhibition rate of Pseudomonas AB-31 to Anabaena cylindrica at a final concentration of 10~6 CFU/mL was only 15.61%.However,Pseudomonas AB-31 combined Rhodopseudomonas JS with a final concentration of 10~5 CFU/mL can reached inhibition rate of 87.40%,and the greater the initial concentration of the two,the more obvious the algae inhibition effect.When the Rhodopseudomonas JS is in stable growth phase,and the Anabaena cylindrica is in the case of the lack of nutrients,the better algae-inhibiting effect;the combination of Pseudomonas AB-31 and Rhodopseudomonas JS inhibit cyanobacteria but has no obvious effect on the growth of chlorophyta.The algae-inhibiting substances secreted by Pseudomonas show different in cyanobacteria and chlorophyta.4.Through the algae inhibition experiment of the two different components,it is determined that the main body of algae inhibition is Pseudomonas AB-31,and Rhodopseudomonas JS has no algae-inhibiting effect,but the supernatant can be strengthened the algae inhibition effect of Pseudomonas AB-31.The inhibition rate against Anabaena cylindrica increased from 27.61%to 86.88%.There are interspecific quorum sensing signal molecules in the photosynthetic bacteria fermentation supernatant,which can induce Pseudomonas to transform physiological characteristics and produce algae-inhibiting substances to inhibit the growth of Anabaena cylindrica.5.Through some physical and chemical properties to preliminarily judge the nature of the induced substances produced by Rhodopseudomonas JS,the induced substances have the ability to resist strong acid and strong alkali,high temperature resistance,less than 1 kD,can be dissolved in ethanol,and have strong water solubility.In summary,the results show that photosynthetic bacteria can enhance the algae-inhibiting effect of eutrophic water bacteria.In practice,the mechanism of photosynthetic bacteria inhibiting algae is likely to be that photosynthetic bacteria enhance the algicidal efficacy of environmental bacteria.