Cometabolic biodegradation of quizalofop-p-ethyl by Methylobacterium populi YC-XJ1 and identification of QPEH1 esterase

BACKGROUND: Quizalofop-p-ethyl (QPE), a unitary R configuration aromatic oxyphenoxypropionic acid ester (AOPP) herbicide, was widely used and had led to detrimental environmental effects. For finding the QPEdegrading bacteria and promoting the biodegradation of QPE, a series of studies were carried out. RESULTS: A QPE-degrading bacterial strain YC-XJ1 was isolated from desert soil and identified as Methylobacterium populi, which could degrade QPE with methanol by cometabolism. Ninety-seven percent of QPE (50 mg/L) could be degraded within 72 h under optimum biodegradation condition of 35°C and pH 8.0. The maximum degradation rate of QPE was 1.4 mg/L/h, and the strain YC-XJ1 exhibited some certain salinity tolerance. Two novel metabolites, 2-hydroxy-6-chloroquinoxaline and quinoxaline, were found by high-performance liquid chromatography/mass spectroscopy analysis. The metabolic pathway of QPE was predicted. The catalytic efficiency of strain YC-XJ1 toward different AOPPs herbicides in descending order was as follows: haloxyfop-pmethyl ≈ diclofop-methyl ≈ fluazifop-p-butyl N clodinafop-propargyl N cyhalofop-butyl N quizalofop-p-ethyl N fenoxaprop-p-ethyl N propaquizafop N quizalofop-p-tefuryl. The genome of strain YC-XJ1 was sequenced using a combination of PacBio RS II and Illumina platforms. According to the annotation result, one α/ß hydrolase gene was selected and named qpeh1, for which QPE-degrading function has obtained validation. Based on the phylogenetic analysis and multiple sequence alignment with other QPE-degrading esterases reported previously, the QPEH1 was clustered with esterase family V. CONCLUSION: M. populi YC-XJ1 could degrade QPE with a novel pathway, and the qpeh1 gene was identified as one of QPE-degrading esterase gene.

Biotechnological and agronomic potential of endophytic pink-pigmented methylotrophic Methylobacterium spp.

The genus Methylobacterium is composed of pink-pigmented facultative methylotrophic (PPFM) bacteria, which are able to synthesize carotenoids and grow on reduced organic compounds containing one carbon (C1), such as methanol and methylamine. Due to their high phenotypic plasticity, these bacteria are able to colonize different habitats, such as soil, water, and sediment, and different host plants as both endophytes and epiphytes. In plant colonization, the frequency and distribution may be influenced by plant genotype or by interactions with other associated microorganisms, which may result in increasing plant fitness. In this review, different aspects of interactions with the host plant are discussed, including their capacity to fix nitrogen, nodule the host plant, produce cytokinins, auxin and enzymes involved in the induction of systemic resistance, such as pectinase and cellulase, and therefore plant growth promotion. In addition, bacteria belonging to this group can be used to reduce environmental contamination because they are able to degrade toxic compounds, tolerate high heavy metal concentrations, and increase plant tolerance to these compounds. Moreover, genome sequencing and omics approaches have revealed genes related to plant-bacteria interactions that may be important for developing strains able to promote plant growth and protection against phytopathogens.

Polyhydroxyalkanoates accumulation by Methylobacterium organophilum CZ-2 during methane degradation using citrate or propionate as cosubstrates.

Methylobacterium organophilum CZ-2 synthesized polyhydroxyalkanoates (PHAs) under nitrogen limitation with CH4 as carbon source and when either citrate or propionate was added as cosubstrates. The highest PHAs content (yPHA) in closed flasks was obtained in the CH4-citrate and CH4-propionate experiments attaining values of 0.82 and 0.68, respectively. M. organophilum CZ-2 cultivated in bioreactors with citrate and continuous CH4 addition yielded a final PHAs concentration of 143 gm(-3) containing hydroxybutyrate (HB), hydroxyvalerate (HV) and hydroxyoctanoate (HO), in a 55:35:10 ratio, with, yPHA of 0.88 and a CH4 elimination capacity (EC) of 20 gm(-3) h(-1). With propionate, the yPHA was 0.3 and the EC around 8 gm(-3) h(-1). From 1H and 13C NMR experiments it was found that the polymer produced with CH4-citrate contained six different monomers: 3HB, 3HV, 4HV, 4-hydroxyheptanoate (4HH), 3HO and 4HO, showing the great versatility of this PHAs producing bacterium.

Production of poly-ß-hydroxybutyrate (PHB) by Methylobacterium organophilum isolated from a methanotrophic consortium in a two-phase partition bioreactor.

The biodegradation of methane, a greenhouse gas, and the accumulation of poly-ß-hydroxybutyrate (PHB) were studied using a methanotrophic consortium and an isolated strain thereof. The specific rates for methane consumption were 100 and [Formula: see text] for the isolate and the consortium, respectively. Also the effect of including 10% (vv(-1)) of silicone oil in a two-phase partitioning bioreactor (TPPB) was assayed for the elimination of 1% methane in air stream. TPPB allowed a 33-45% increase of methane elimination under growing conditions. Nitrogen limitation was assayed in bioreactors to promote PHB production. Under this condition, the specific methane degradation rate remained unchanged for the consortium and decreased to [Formula: see text] for the isolated strain. The accumulated PHB in the reactor was 34% and 38% (ww(-1)) for the consortium and the isolate, respectively. The highest productivity was obtained in the TPPB and was 1.61 mg(PHB)g(x)(-1) h(-1). The CZ-2 isolate was identified as Methylobacterium organophilum, this is the first study that reports this species as being able to grow on methane and accumulate up to 57% (ww(-1)) of PHB under nitrogen limitation in microcosm experiments.

Genetic and metabolic diversity of pink-pigmented facultative methylotrophs in phyllosphere of tropical plants

Diversity of Pink-Pigmented Facultative Methylotrophs (PPFMs) in phyllosphere of cotton, maize and sunflower was determined based on differential carbon-substrate utilization profile and Random Amplified Polymorphic DNA data. Results indicate that six diversified groups of PPFMs are found in these crops. Sunflower and maize phyllosphere harbor four different groups of methylobacteria while cotton has only two groups.

A diversidade de microrganismos metilotróficos facultativos pigmentados (PPFMs) na filosfera de algodão, milho e girassol foi determinada baseada no perfil diferencial de utilização de substratos de carbono e em dados de RAPD. Os resultados indicaram a existência de seis grupos diferentes de PPFMs nessas plantas. As filosferas de girassol e milho apresentaram quatro grupos diferentes de metilobactérias enquanto a de algodão apresentou apenas dois grupos.

Capillary electrophoresis-mass spectrometry of citrus endophytic bacteria siderophores.

CE-ESI-MS with a liquid sheath interface and IT mass analyzer was used for analysis of siderophores from different strains of Methylobacterium spp. citrus endophyte extracts. Three Methylobacterium strains were investigated according to positive bioassay tests. Bacteria cultures were grown under Fe(III) absence (siderophore producing cultures) and under Fe(III) presence (control cultures). Siderophores were extracted from culture supernatant with polystyrene resins. BGE and sheath-liquid composition were optimized, respectively, in order to assure both, best peak resolution and ESI-MS sensitivity. The best analysis conditions were obtained with 100 mmol/L ammonium bicarbonate at pH 8 as BGE and methanol:H(2)O 25:75 + 0.05% formic acid as sheath liquid. CZE-ESI-MS analysis revealed two possible siderophores, according to bacterium species, presenting M(r) of 1004.3 and 798.3 Da.