光合细菌Rhodopseudomonas faecalis JS提升细菌抑藻能力的机制研究

Enhancement of Algaecidal Capacity of in situ Bacteria by Rhodopseudomonas faecalis JS

抑藻细菌在蓝藻水华的发展及消亡过程中起着重要的调节作用。增强抑藻细菌的抑藻能力将有助于加速蓝藻水华的消散,然而目前尚缺乏有效的原位调控手段。为了探究光合细菌Rhodopseudomonas faecalis JS对抑藻细菌抑藻作用的促进作用及其机理,本研究首先进行富营养化水体土著细菌的抑藻实验,研究光合细菌R.faecalis JS对原位菌群抑藻能力的促进作用;通过对原位菌群中纯菌的分离与鉴定,进一步研究R.faecalis JS对不同种属细菌抑藻能力的促进作用;通过乙醇提取、HPLC及液质联用技术,对R.faecalis JS促进细菌抑藻作用的活性物质进行分离鉴定,探究R.faecalis JS对抑藻细菌抑藻能力的促进机理。结果表明:①光合细菌R.faecalis JS的发酵液能够增强富营养化水体原位菌群的抑藻效果。②从原位混合菌群中分离得到38株纯菌,有6株细菌(AB-3、AB-6、AB-13、AB-26、AB-31、AB-38)的抑藻率在添加R.faecalis JS发酵液后出现显著性提升,其中P.putida AB-31菌抑藻能力的增幅最大,其抑藻率由13.59%升至81.70%。这些细菌的系统分类学鉴定结果显示,R.faecalis JS发酵液能够提升抑藻作用的抑藻细菌都属于Pseudomonadota假单胞菌门,表明R.faecalis JS提升细菌抑藻能力具有门水平上的特异性。③对R.faecalis JS发酵液中的活性物质进行分离,得到22种潜在的活性代谢物,验证发现代谢物中的N-己酰基-DL-高丝氨酸内脂和N-丁酰基-DL-高丝氨酸内脂能够显著提升AB-31菌的抑藻作用,说明光合细菌R.faecalis JS可能通过释放群体感应信号分子的方式提升抑藻细菌的抑藻作用。研究显示,光合细菌R.faecalis JS具有原位提升细菌抑藻作用的潜力,这将为蓝藻水华的治理提供新的方法和思路。

In recent years,the frequent occurrence of harmful algal blooms(HABs)has severely damaged freshwater ecosystems worldwide,while efficient in situ bloom control methods are still lacking.Microalgae-inhibiting bacteria are critical in modulating the life cycle of cyanobacterial proliferation,and their enhanced inhibitory capabilities may accelerate bloom decay.This study aims to elucidate the mechanisms by which the photosynthetic bacterium Rhodopseudomonas faecalis JS enhances the suppressive effects of these algae-restraining microorganisms.In this study,the enhancement effect of photosynthetic bacterium Rhodopseudomonas faecalis JS on the algal inhibition ability of in situ bacteria was first investigated through the algal inhibition experiments with indigenous bacteria in eutrophic water bodies.The promotion effect of R.faecalis JS on the algal inhibition ability of different bacterial species was further investigated through the isolation and identification of the pure bacteria from mixed colonies.Bioactive compounds responsible for these enhancements in R.faecalis JS were isolated and identified using ethanol extraction,HPLC and liquid-liquid chromatography.The results showed that the fermentation broth of photosynthetic bacterium R.faecalis JS enhanced the algal inhibition effect of in situ bacterial flora in eutrophic water bodies.Among the 38 isolated pure bacterial strains,six(designated AB-3,AB-6,AB-13,AB-26,AB-31 and AB-38)displayed an increased ability to suppress algal growth when synergistically combined with R.faecalis JS.Notably,strain AB-31 exhibited the most pronounced enhancement,with its algal inhibition efficacy rising from a modest 13.59%to an impressive 81.70%.The phylogenetic identification of these bacteria showed that all bacteria whose algal inhibition was enhanced by the R.faecalis JS belonged to the Pseudomonadota phylum.Given that R.faecalis JS also belongs to the Pseudomonadaceae phylum,this suggests that the enhancement of the bacterial algal inhibition ability by R.faecalis JS is specific at the phylum level.The fermentation broth of R.faecalis JS was extracted with ethanol,separated by HPLC and analyzed by liquid mass spectrometry to obtain 22 potentially active metabolites.Final validation revealed that among the metabolites,N-hexanoyl-DL-homoserine lactone and N-butanoyl-DL-homoserine lactone significantly enhanced the algal inhibitory effect of AB-31 bacterium.This suggests that the photosynthetic bacterium R.faecalis JS may enhance the algal inhibition of bacteria by releasing quorum sensing signaling molecules.The findings of this research reveal that Rhodopseudomonas faecalis JS possesses a remarkable capability to amplify the algae-suppressing properties of indigenous bacterial populations.This discovery introduces novel strategies and conceptual frameworks to address the pressing issue of cyanobacterial bloom management.