Growth and denitrifying activity of Xanthobacter autotrophicus CECT 7064 in the presence of selected pesticides

The effects of the application of nine pesticides used commonly in agriculture (aldrin, lindane, dimetoate, methylparathion, methidation, atrazine, simazine, captan and diflubenzuron) on growth, CO₂ production, denitrifying activity [as nitrous oxide (N₂O) released] and nitrite accumulation in the culture medium by Xanthobacter autotrophicus strain CECT 7064 (Spanish Type Culture Collection) (a micro-organism isolated from a submerged fixed-film) were studied. The herbicide atrazine and the insecticide dimetoate totally inhibited growth and biological activity of X. autotrophicus at 10 mg l⁻¹, while the rest of the tested pesticides delayed the growth of strain CECT 7064 but did not drastically affect the bacterial growth after 96 h of culture. The denitrifying activity of X. autotrophicus was negatively affected by the pesticides application with the exception of fungicide captan. The release of N₂O was strongly inhibited by several pesticides (aldrin, lindane, methylparathion, methidation and diflubenzuron), while dimetoate, atrazine and simazine inhibited totally the denitrifying activity of the strain. The effects of the pesticides on denitrifying submerged fixed-film reactor are discussed.     

Synthesis of 5-Alkyl-5-methyl-2-hydroxy-2-cyclopentenones

A hydrogen bacterium strain, N34, and its oxygen-resistant segregant strain, Y38, were subjected to a taxonomical study. Since both strains were capable of N₂-fixation, N₂-fixing facultative hydrogen autotrophs listed in “Bergey’s Manual of Systematic Bacteriology” were used for comparison. Both strains produced a water-insoluble carotenoid pigment, zeaxanthin dirhamnoside, indicating that both should be classified into the genus Xanthobacter. Then, the differential characteristics of the two species of the genus Xanthobacter, X. autotrophicus and X. flavus, were investigated as to both strains. The vitamin requirement, the sensitivity to oxygen under autotrophic conditions, the inducibility of hydrogenase, the substrate range of carbohydrates and N₂-fixing growth characteristics of both strains were almost completely opposite to those of X. flavus. Moreover, both strains coincided exactly with X. autotrophicus in morphological and other physiological characteristics. From these results both strains were identified as Xanthobacter autotrophicus.     

Nickel requirement for chemolithotrophic growth in hydrogen-oxidizing bacteria

In a comparative study the requirement of several strains of autotrophic hydrogen-oxidizing bacteria for nickel was examined. Autotrophic growth was studied both in liquid media, previously freed from trace metals; and on solidified media, using a plate diffusion assay. The latter assay was based on the observation that EDTA causes complete inhibition of autotrophic growth on agar medium as a result of nickel deficiency. Nickel was shown to be required as a trace element in five strains of Alcaligenes eutrophus, in two strains of Xanthobacter autotrophicus, in Pseudomonas flava, in Arthrobacter spec. 11X and in strain 12X. In these bacteria nickel was not replaceable by cobalt, copper, manganese or zinc ions. No significant nickel requirement was detected by these methods, however, for Paracoccus denitrificans and Nocardia opaca 1b.     

Population Dynamics of Two Toluene Degrading Bacterial Species in a Contaminated Stream

Toluene uptake by a benthic biofilm community was previously shown to vary seasonally from 0.03 m hr⁻¹ in winter to 0.2 m hr⁻¹ in summer in a solvent-contaminated stream of the Aberjona watershed. We used quantitative PCR to estimate the population dynamics of previously isolated species of toluene-degrading Xanthobacter autotrophicus and Mycobacterium sp. in both toluene-contaminated and uncontaminated reaches of the stream, and to estimate their relative roles in overall biodegradation rate. Quantification using specific 16S rDNA primers for X. autotrophicus and Mycobacterium sp. showed that populations of both species were much larger in the toluene-contaminated than the toluene-free reach, in agreement with earlier culture-based investigations. A relatively brief bloom of X. autotrophicus occurred in the contaminated reach in the summer, while Mycobacterium sp. populations occurred at elevated densities for more than 5 months. Calculations showed that Mycobacterium, previously thought to be less important than Xanthobacter in annual toluene degradation based on single time-point CFU estimates, appears actually more important because of this longer persistence.     

Bacterial degradation of glycol ethers

Assimilation of ethyleneglycol (EG) ethers by polyethyleneglycol-utilizing bacteria was examined. Ethyleneglycol ether-utilizing bacteria were also isolated from soil and activated sludge samples by enrichment-culture techniques. Three strains (4-5-3, EC 1-2-1 and MC 2-2-1) were selected and characterized as Pseudomonas sp. 4-5-3, Xanthobacter autotrophicus, and an unidentified gram-negative, non-spore-forming rod respectively. Their growth characteristics were examined: Pseudomonas sp. 4-5-3 assimilated EG (diethyleneglycol, DEG) monomethyl, monoethyl and monobutyl ethers, DEG, propanol and butanol. X. autotrophicus EC 1-2-1 grew well on EG monoethyl and monobutyl ethers, EG and primary alcohols (C₁-C₄), and slightly on EG monomethyl ether. The strain MC 2-2-1 grew on EG monomethyl ether, EG, primary alcohols (C₁-C₄), and 1,2-propyleneglycol (PG). The mixed culture of Pseudomonas sp. 4-5-3 and X. autotrophicus EC 1-2-1 showed better growth and improved degradation than respective single cultures towards EG monomethyl, monoethyl or monobutyl ethers. Intact cells of Pseudomonas sp. 4-5-3 degraded various kinds of monoalkyl ethers, which cannot be assimilated by the strain. Metabolic products were characterized from reaction supernatants of intact cells of Pseudomonas sp. 4-5-3 with EG or DEG monoethyl ethers: they were analyzed by thin-layer chromatography and GC-MS and found to be ethoxyacetic acid and ethoxyglycoxyacetic acid. Also, PG monoalkyl ethers (C₁-C₄), dipropyleneglycol monoethyl and monomethyl ethers and tripropyleneglycol monomethyl ether were assimilated by polypropyleneglycol-utilizing Corynebacterium sp. 7.     

Cloning and expression of the genes encoding the propene monooxygenase from Xanthobacter, Py2

Xanthobacter Py2 grows on propene as sole carbon source, converting propene to propene oxide (epoxypropane) using an alkene-specific monooxygenase, as the first step in catabolism. Four mutants, NZ1–4, with a propene^– propene oxide⁺ phenotype were isolated by 1-methyl-3-nitro-1-nitrosoguanidine mutagenesis or by enrichment with the suicide substrate vinylidene chloride, and were shown to have lost the ability to convert alkenes to epoxides. All four mutants were complemented by a number of clones of Xanthobacter Py2 chromosomal DNA in the broad-host-range cosmid pLAFR5, some of which appeared to be non-overlapping. Representatives of the different clones obtained were transferred into Xanthobacter autotrophicus JW33 and one, pNY2, the most frequently isolated clone, was shown to express an inducible, fully functional propene monooxygenase. Subcloning revealed that all four mutants were complemented by a 2.4-kb EcoRI-PstI fragment situated at one end of the cosmid insert. However, activity in X. autotrophicus JW33 could only be expressed from pNY2, containing the complete insert (25 kb), suggesting a large operon or some form of long-range control. pNY2 failed to express in E. coli. In X. autotrophicus JW33 [pNY2] at least three new polypeptides were evident after induction with propene compared with a control carrying only the cosmid pLAFR5.     

Biodegradation of dichloroacetic acid by entrapped and adsorptive immobilized Xanthobacter autotrophicus GJ10

The degradation of dichloroacetic acid (DCA) by free, Ca-alginate entrapped and adsorptive immobilized cells of Xanthobacter autotrophicus GJ10 has been studied in various experimental systems. Entrapped cells tolerated increasing concentrations of DCA better than free cells. Free and adsorptive immobilized cells degraded DCA most effectively at maximum O₂ supply, 34°C and an initial pH value of 8.0. The degradation of high DCA concentrations led to a decrease in the pH value and to a stagnation of mineralization, particularly with free or entrapped cells. Due to the stabilization of pH, the supplementation of acetate or succinate resulted in a complete degradation of higher DCA concentrations. Higher degradation rates than in shake cultures were achieved in air-bubble and packed-bed fermentors. DCA was mineralized faster by free or entrapped X. autotrophicus GJ10 than by adsorptive immobilized cells, which, however, were able to remove higher DCA concentrations. The results of the recent investigations with immobilized X. autotrophicus GJ10 are an important prerequisite for the application of this bacterium in waste treatment systems. Correspondence to: U. Heinze     

The membrane-bound hydrogenase of Alcaligenes eutrophus: II. Localization and immunological comparison with other hydrogenase systems

Immunological comparison of the soluble and the membrane-bound hydrogenase of Alcaligenes eutrophus revealed no common antigenic determinants shared by the native proteins, however, a small amount of cross-reacting material was detected after freezing and thawing. Immune precipitation assays supported previous observations indicating the membrane-bound hydrogenase to be localized in the outer surface of the cytoplasmic membrane.The membrane-bound hydrogenases of A. eutrophus and Pseudomonas pseudoflava showed close immunological relationship, and material cross-reacting to both antisera was found in membrane extracts of all hydrogen-oxidizing strains of Pseudomonas, Alcaligenes and Aquaspirillum. Material cross-reacting to the membrane-bound hydrogenase of Xanthobacter autotrophicus GZ 29 was found only in a few hydrogen-oxidizing bacteria. Material cross-reacting to the soluble hydrogenase of A. eutrophus was detected in strains of A. eutrophus and A. ruhlandii only.Comparison of the membrane-bound hydrogenase of A. eutrophus, P. pseudoflava and X. autotrophicus with hydrogenases of other physiological bacterial groups revealed serological relationship to the membrane-bound hydrogenases of the hydrogen bacteria and of Chromatium vinosum only. The results are discussed in terms of physiological, taxonomical, and evolutionary aspects.     

不同季节艾比湖湿地盐角草根际nirS-型与nirK-型反硝化细菌群落组成分析

旨在了解艾比湖湿地盐生植物盐角草根际与非根际中不同类型反硝化细菌的分布及其随季节变化情况,为温带干旱地区荒漠盐化生态系统的代表-艾比湖湿地在生态植被恢复过程中,由微生物推动的土壤氮素循环过程提供数据支撑。采集了艾比湖湿地夏、秋、春三个季节的盐角草根际和非根际土壤样本,通过高通量测序技术,比较分析了nirS-型和nirK-型两种类型的反硝化细菌的多样性和群落结构特点;利用RDA (redundancy analysis)探究了土壤理化因素对反硝化细菌多样性及群落结构的影响。艾比湖湿地盐角草根际与非根际中,nirS-型和nirK-型反硝化细菌多样性最高的为秋季根际土壤样本;各土壤样本中的反硝化细菌多样性均呈现根际>非根际。盐角草各土壤样本中的nirS-型反硝化细菌在门分类水平上隶属于变形菌门(Proteobacteria),厚壁菌门(Firmicutes)和放线菌门(Actinobacteria),而nirK-型反硝化细菌在门水平上分类仅包括了Proteobacteria和Firmicutes。Proteobacteria在各土壤样本中的占比均较高;其中Gamma-Proteobacteria的盐单胞菌属(Halomonas)和假单胞菌属(Pseudomonas)是各土壤样本所共有的nirS-型反硝化菌的优势菌属,但它们在每个土壤样本中的相对丰度各有差异。Alpha-Proteobacteria的根瘤菌属(Rhizobium)是盐角草各土壤样本中较为广泛存在的nirK-型反硝化细菌。艾比湖湿地盐角草各土壤样本中的反硝化细菌群落结构存在着一定的差异。RDA结果显示含水量、有机质、全氮和铵态氮等对各土壤样本中的nirS-型反硝化细菌的多样性影响较大,含水量、有机质、全氮、碱解氮等是nirK-型反硝化细菌多样性的主要影响因素。土壤电导率、全磷、全钾、全氮和碱解氮协同影响nirS-型反硝化细菌的群落结构,有机质、速效钾、速效磷、pH和硝态氮是nirK-型反硝化细菌群落结构组成的主要影响因素。艾比湖湿地反硝化细菌呈现季节性变化,nirS-型和nirK-型反硝化细菌以不同的主要菌属,共同推进湿地反硝化作用。而对于湿地生态系统的保护,则需要进行长期而广泛的土壤状态评估和土壤反硝化微生物菌群的动态监测。     

Comparative Study of the Ability of Three Xanthobacter Species To Metabolize Cycloalkanes

The ability of three species of Xanthobacter to metabolize cyclohexane and its derivatives has been compared. Xanthobacter flavus was unable to utilize any of the cycloalkanes under investigation. X. autotrophicus was unable to utilize cyclohexane but was able to grow with a limited range of substituted cycloalkanes, including cyclohexanol and cyclohexanone. Comparison of a previously isolated cyclohexane growing Xanthobacter sp. with X. flavus and X. autotrophicus indicated it to be closely related to X. autotrophicus. Studies with cell-free extracts have indicated that the route of metabolism for cyclohexanol by X. autotrophicus is the same as that shown for the cyclohexane growing Xanthobacter sp., proceeding via cyclohexanol→cyclohexanone→ ε-caprolactone→→ adipic acid. A comparison of the cyclohexanol dehydrogenase found in X. autotrophicus with that found in the cyclohexane-growing Xanthobacter sp. indicated these enzymes to be distinctly different from one another on the basis of substrate specificity, molecular weight, and pH optima. The cyclohexanone monooxygenase enzymes found in the two bacteria were also found to be different when the pH optima and cofactor specificity of the two enzymes were compared. Preliminary genetic studies on the cyclohexane-growing Xanthobacter sp. have indicated that there are no plasmids present in this bacterium. The presence of RP4 in the Xanthobacter sp. can be detected following its conjugation with an RP4-carrying Escherichia coli strain.     

Denitrification in lucerne nodules is not involved in nitrite detoxification

Dissimilatory reduction of ionic nitrogen oxides to gaseous forms such as nitrous oxide or nitrogen can be carried out by free living or symbiotic forms of some strains of Rhizobium meliloti. In this paper we investigate whether bacteroid denitrification plays a role in the alleviation of the inhibitory effects of nitrate on nitrogen fixation both in bacteroid incubations as in whole nodules. The presence of a constitutive nitrate reductase (NR) activity in isolated bacteroids caused nitrite accumulation in the incubation medium, and acetylene reduction activity in these bacteroids was progressively inhibited, since nitrite reductase (NiR) activity was unable to reduce all the nitrite produced by NR and denitrification occurred slowly. Even nodules infiltrated with nitrate and nitrite failed to increase gaseous forms of nitrogen substantially, indicating that nitrite availability was not limiting denitrification by bacteroids. In spite of the low rates of bacteroidal denitrification, the effect of nodule denitrification on the inhibition of nitrogen fixation by nitrate in whole plants was tested. For that purpose, lucerne plants (Medicago sativa L. cv. Aragon) were inoculated with two Rhizobium meliloti strains: 102-F-65 (non denitrifying) and 102-F-51 (a highly denitrifying strain). After a seven days nitrate treatment, both strains showed the same pattern of inhibition, and it occurred before any nitrate or nitrite accumulation within the nodules could be detected. This observation, together with the lack of alleviation of the ARA inhibition in the denitrifying strain, and the limited activity of dissimilatory nitrogen reduction present in these bacteroids, indicate a role other than nitrite detoxification for denitrification in nodules under natural conditions.     

Rhodopseudomonas sphaeroides forma sp. denitrificans,a denitrifying strain as a subspecies of Rhodopseudomonas sphaeroides

From polluted water of a lagoon pond a new type of denitrifying photosynthetic purple bacteria was isolated. With respect to morphology, fine structure, photopigments, requirement for growth factors, the range of utilization of organic substrates for phototrophic growth and DNA base ratio, the denitrifying strains show the closest resemblance to Rhodopseudomonas sphaeroides and were therefore described as a subspecies named R. sphaeroides forma sp. denitrificans. The new isolates grow well with nitrate anaerobically in the dark accompanying the evolution of nitrogen gas. They cannot assimilate nitrate as the nitrogen source for growth.     

干湿交替对生物滞留系统中氮素功能微生物群落的影响

【目的】为探究生物滞留系统干湿交替下环境因子对氮素功能微生物群落的影响。【方法】应用高通量测序技术(Illumina MiSeq PE300),并以amoA和nirS功能基因为分子标记,对无植物型和植物型生物滞留系统在干湿交替下不同土壤空间位置(种植层、淹没层)的硝化和反硝化细菌的多样性和群落结构进行研究,并对微生物群落与环境因子的相互关系进行相关性分析。【结果】微生物种群的功能基因存在显著的空间差异,相比淹没层,种植层的功能细菌更丰富。种植层的OTUs高于淹没层,而进水再湿润促使两种功能基因在种植层和淹没层的OTUs占比差异性增大。群落组成分析表明,amoA型硝化细菌和nirS型反硝化细菌的优势细菌门均为变形菌门(Proteobacteria)。虽然植物根系对氮素功能微生物的多样性指数影响不显著,但在属水平上,植物系统种植层的反硝化菌群种类高于淹没层,而无植物系统则刚好相反。CCA/RDA分析表明,土壤空间位置是影响硝化和反硝化菌群结构的最重要环境因子。【结论】本研究证实干湿交替运行下生物滞留系统中的氮素功能微生物群落受土壤空间位置、水分含量和植物根系的共同调控,其机制有待进一步研究。     

Biodegradation of dichloroacetic acid by freely suspended and adsorptive immobilized Xanthobacter autotrophicus GJ10 in soil

Xanthobacter autotrophicus GJ10 was applied in a packed-bed fermentor to degrade dichloroacetic acid (DCA) in batch-, semicontinuous and continuous culture. Degradation has been studied with freely suspended and adsorptive immobilized cells. To imitate natural soil systems, the fermentor was filled with sand. Concentrations of up to 20 mm DCA were degraded completely. If higher initial concentrations were used, the decrease in pH value inhibited further growth and degradation. In continuous culture the fermentor was inoculated additionally with activated sludge. Over a period of 2 weeks the specialized strain could be retained and no decrease in metabolic activity was observed. A decrease in degradation of DCA was observed when succinate was added as a second substrate. The haloacid dehalogenase was found to be induced by DCA. Non-induced cells showed typical repression of catabolites and diauxic growth with succinate as co-substrate. The results demonstrate that X. autotrophicus GJ10 might be suitable for applications in biological waste treatment systems. Correspondence to: H.-J. Rehm     

Shotgun proteomics of Xanthobacter autotrophicus Py2 reveals proteins specific to growth on propylene

Coenzyme M (CoM, 2-mercaptoethanesulfonate), once thought to be exclusively produced by methanogens, is now known to be the central cofactor in the metabolism of short-chain alkenes by a variety of aerobic bacteria. There is little evidence to suggest how, and under what conditions, CoM is biosynthesized by these organisms. A shotgun proteomics approach was used to investigate CoM-dependent propylene metabolism in the Gram-negative bacterium Xanthobacter autotrophicus Py2. Cells were grown on either glucose or propylene, and the soluble proteomes were analyzed. An average of 395 proteins was identified from glucose-grown replicates, with an average of 419 identified from propylene-grown replicates. A number of linear megaplasmid (pXAUT01)-encoded proteins were found to be specifically produced by growth on propylene. These included all known to be crucial to propylene metabolism, in addition to an aldehyde dehydrogenase, a DNA-binding protein, and five putative CoM biosynthetic enzymes. This work has provided fresh insight into bacterial alkene metabolism and has generated new targets for future studies in X. autotrophicus Py2 and related CoM-dependent alkene-oxidizing bacteria.     

Identification of Efficient Denitrifying Bacteria from Tannery Wastewaters in Ethiopia and a Study of the Effects of Chromium III and Sulphide on Their Denitrification Rate

In order to identify potential microorganisms with high denitrifying capacity from tannery wastewaters, 1000 pure cultures of bacterial isolates from Modjo Tannery Pilot and Ethio-tannery wastewater treatment plants (WWTP), in Ethiopia, were investigated. Twenty-eight isolates were selected as efficient denitrifiers. These were Gram-negative rods, oxidase and catalase positive denitrifying organisms. The 28 denitrifying strains were further classified according to their biochemical fingerprints into three different phylogenetic groups (BPT1, BPT2 and BPT3) and seven singles. Isolates B79^T, B11, B12, B15, B28 and B38 belonging to the BPT3 cluster were found to be the most efficient denitrifying bacteria. All phenotypic studies, including cellular fatty acid profiles, showed that the 6 BPT3 isolates were closely related to each other. The 16S rRNA partial sequence analysis of type strain B79^T(CCUG 45880) indicated a sequence similarity of 99% to Brachymonas denitrificans JCM9216 (D14320) in the β-subdivision of proteobacteria. Further studies of the effects of chromium III and sulphide on the six Brachymonas denitrificans strains indicated that denitrification by the isolates were inhibited 50% at concentrations of 54 and 96 mg/l, respectively. The efficient isolates characterized in this study are of great value because of their excellent denitrifying properties and relatively high tolerance to the concentrations of toxic compounds (70 mg chromium/l and 160 mg sulphide/l) prevailing in tannery wastewaters.     

Biodegradation kinetics of trichloroethylene and1,2-dichloroethane by Burkholderia (Pseudomonas)cepacia PR131 and Xanthobacter autotrophicus GJ10.

The biodegradation kinetics for chlorinated aliphatic hydrocarbons trichloroethylene (TCE) by Burkholderia (Pseudomonas) cepacia PR1₃₁ and for1,2-dichloethane (1,2-DCA) by Xanthobacter autotrophicus GJ10 were determinedusing an initial rate method to determine the applicable rate law and relevant kinetic parametersunder aerobic conditions. A first order linear rate law applied to 1,2-DCA biodegradation by X. autotrophicus GJ10. The first order rate constant was determined to be 0.014 ml/min/mg.A non-linear rate law applied to TCE biodegradation by B. cepacia PR1₃₁.The maximum specific degradation rate constant was determined to be 0.8 nmol/min/mg protein,and the half saturation constant was determined to be 0.026 mM (3.47 ppm). Error analysisperformed on our analytical methods and computations, using a logarithmic differentiationmethod, indicated the relative error of our reported rate constants to be approximately 17%.Knowledge of the kinetic rate laws and kinetic parameters governing the biodegradation of TCEand 1,2-DCA by these strains will further the application of these strains in the environmental fieldand in waste treatment applications.     

Vigorous denitrification by a heterotrophic nitrifier of the genusAlcaligenes

A heterotrophic nitrifyingAlcaligenes sp., previously isolated from soil and shown to be very active in the aerobic oxidation of pyruvic oxime (and hydroxylamine) to nitrite, is now shown to be quite active as a denitrifier. The bacterium synthesized nitrite, nitrous oxide, and nitrogen gas from nitrate when grown anaerobically and could individually reduce nitrate, nitrite, nitric oxide, and nitrous oxide to nitrogen gas when these nitrogen-oxides were added to dense cell suspensions. No evidence was obtained for the release of nitric oxide during reduction of nitrate and nitrite. The specific rates of reduction of the nitrogen-oxide were similar to those of well-known laboratory strains of denitrifying bacteria. The induction of an entire set of denitrifying enzymes at normal levels in a heterotrophic nitrifier is novel. The nitrification-denitrification capability ofAlcaligenes sp. may confer certain advantages to this and analogous organisms in the environment.     

Oxygen tolerance of strictly aerobic hydrogen-oxidizing bacteria

Growth of various bacteria, especially aerobic hydrogen-oxidizing bacteria, in the presence of 2 to 100% (v/v) oxygen in the gas atmosphere was evaluated. The bacterial strains included Alcaligenes eutrophus, A. paradoxus, Aquaspirillum autotrophicum, Arthrobacter spec. strain 11X, Escherichia coli, Arthrobacter globiformis, Nocardia opaca, N. autotrophica, Paracoccus denitrificans, Pseudomonas facilis, P. putida, and Xanthobacter autotrophicus. Under heterotrophic conditions with fructose or gluconate as substrates neither colony formation on solid medium nor the growth rates in liquid media were drastically impaired by up to 100% oxygen. In contrast, autotrophic growth — with hydrogen, carbon dioxide and up to 80% oxygen in the gas atmosphere — was strongly depressed by high oxygen concentrations. However, only the growth rate, not the viability of the cells, was decreased. Growth retardation was accompanied by a decrease of hydrogenase activity.The work was supported by the Deutsche Forschungsgemeinschaft.     

Plant growth-promoting rhizobacteria isolation from rhizosphere of submerged macrophytes and their growth-promoting effect on Vallisneria natans under high sediment organic matter load

Sediment organic matter is a key stressor for submerged macrophyte growth, which negatively impacts the ecological restoration of lakes. Plant growth-promoting rhizobacteria (PGPR) were screened from the rhizosphere of submerged macrophytes and used due to their promoting effect on Vallisneria natans under a high sediment organic matter load. Root exudates were used as the sole carbon source to obtain the root affinity strains. Eight isolates were selected from the 61 isolated strains, based on the P solubilization, IAA production, cytokinins production and ACC deaminase activity. The analysis of the 16S rDNA indicated that one strain was Staphylococcus sp., while the other seven bacterial strains were Bacillus sp. They were all listed in low-risk groups for safety use in agricultural practices. The plant height significantly increased after inoculation with PGPR strains, with the highest rate of increase reaching 96%. This study provides an innovative technique for recovering submerged macrophytes under sediment organic matter stress.