Bacterial Manganese Oxidation Research Articles

Phenol and 17β-estradiol removal by Zoogloea sp. MFQ7 and in-situ generated biogenic manganese oxides: Performance, kinetics and mechanism

The pollution of multifarious pollutants such as heavy metal, organic compounds, and nitrate are a hot research topic at present. In this study, the functions of Zoogloea sp. MFQ7 and its biological precipitation formed during bacterial manganese oxidation on the removal of phenol and 17β-estradiol (E2) were investigated. Strain MFQ7, a manganese-oxidizing bacteria, can remove 98.34% of phenol under pH of 7.1, a temperature of 30 ℃ and Mn2+ concentration of 24.34 mg L−1, additionally, the optimum E2 removal by strain MFQ7 was 100.00% at pH of 7.1, temperature of 28 ℃ and Mn2+ concentration of 28.45 mg L−1 by using response surface methodology (RSM) based on Box-Behnken design (BBD) model. The maximum adsorption capacity of bio-precipitation for phenol and E2 was 201.15 mg g−1 and 65.90 mg g−1, respectively. Furthermore, adsorption kinetics and isotherms analysis, XPS, FTIR spectra, Mn(III) trapping experiments elucidated chemical adsorption and Mn(III) oxidation contribute to the removal of phenol and E2 by biogenic manganese oxides. These findings indicated that the adsorption and oxidation of manganese are expected to be one of the effective means to remove these typical organic pollutants containing phenol and E2.

Analysis of in situ manganese(II) oxidation in the Columbia River and offshore plume: linking Aurantimonas and the associated microbial community to an active biogeochemical cycle

The Columbia River is a major source of dissolved nutrients and trace metals for the west coast of North America. A large proportion of these nutrients are sourced from the Columbia River Estuary, where coastal and terrestrial waters mix and resuspend particulate matter within the water column. As estuarine water is discharged off the coast, it transports the particulate matter, dissolved nutrients and microorganisms forming nutrient-rich and metabolically dynamic plumes. In this study, bacterial manganese oxidation within the plume and estuary was investigated during spring and neap tides. The microbial community proteome was fractionated and assayed for Mn oxidation activity. Proteins from the outer membrane and the loosely bound outer membrane fractions were separated using size exclusion chromatography and Mn(II)-oxidizing eluates were analysed with tandem mass spectrometry to identify potential Mn oxidase protein targets. Multi-copper oxidase (MCO) and haem-peroxidase enzymes were identified in active fractions. T-RFLP profiles and cluster analysis indicates that organisms and bacterial communities capable of oxidizing Mn(II) can be sourced from the Columbia River estuary and nearshore coastal ocean. These organisms are producing up to 10 fM MnO₂ cell⁻¹ day⁻¹. Evidence for the presence of Mn(II)-oxidizing bacterial isolates from the genera Aurantimonas, Rhodobacter, Bacillus and Shewanella was found in T-RFLP profiles. Specific Q-PCR probes were designed to target potential homologues of the Aurantimonas manganese oxidizing peroxidase (Mop). By comparing total Mop homologues, Aurantimonas SSU rRNA and total bacterial SSU rRNA gene copies, it appears that Aurantimonas can only account for ~1.7% of the peroxidase genes quantified. Under the broad assumption that at least some of the peroxidase homologues quantified are involved in manganese oxidation, it is possible that other organisms oxidize manganese via peroxidases.

Microalgal-facilitated bacterial oxidation of manganese

In the presence of unicellular microalgae, bacterial manganese oxidation was increased by up to ten times the rate produced by bacterial oxidation alone. Azide-poisoned controls demonstrated that the manganese-oxidizing bacteria were active in the algal-bacterial oxidation of manganese. Scanning electron microscopy showed that oxide formation occurred in a number of structurally different deposits on the surface of the alga. Studies involving algal cell fractionation showed that bacterial manganese oxidation was facilitated by the algal cell wall, possibly via Mn2+ adsorption. Variations in growth conditions had an effect on algal-bacterial oxide formation and composition. High nutrient (yeast extract, peptone and/or sucrose) levels favored microbial growth but lowered oxide formation, whereas optimal levels of manganese oxide formation required minimal media. High concentrations of either organic nutrients or mineral salts promoted manganese carbonate precipitation.

Genetic analysis of the marine manganese-oxidizing Bacillus sp. strain SG-1: protoplast transformation, Tn917 mutagenesis, and identification of chromosomal loci involved in manganese oxidation.

Mature spores of the marine Bacillus sp. strain SG-1 bind and oxidize manganese(II), thereby becoming encrusted with a manganese(IV) oxide. Both the function and mechanism of this oxidation are unknown, although evidence suggests that spore coat proteins are involved. To further study this phenomenon, methods of genetic analysis were developed for SG-1. By a modified protoplast transformation procedure, SG-1 was transformed (approximately 100 transformants per micrograms of DNA) with several different plasmids of gram-positive origin. Transposon Tn917, delivered on the temperature-sensitive plasmid pLTV1, was used to generate mutants of SG-1. Conditions were established that allowed 98% plasmid loss and insertions to be recovered at a frequency of 10(-3). Each mutant was found to be the result of a single insertion event. Restriction analysis of 27 mutants that do not oxidize manganese but still sporulate localized 17 of the insertions within two regions of the chromosome (termed Mnx regions), and a physical map of these regions was generated. Analysis of 18 transposon integrants in which manganese oxidation was unaffected revealed random transposon integration, with none of their insertions mapping within the Mnx regions. The Mnx regions were cloned from wild-type SG-1, and the largest region, carried on the lactococcal plasmid pGK13, was used to complement in trans one of the nonoxidizing mutants. These results demonstrate that the Mnx regions encode factors that are required for the oxidation of manganese, and this represents the first report identifying genes involved in bacterial manganese oxidation.

Production of Metallogenium-like particles by heterotrophic manganese-oxidizing bacteria collected from a lake

As a model of chemically stratified structure of environment typical to the chemocline of lakes, a semi- solid gradient medium was prepared to cultivate hetero- trophic manganese-oxidizing bacteria originally collected from a lake. The bacteria growing under the conditions described produced extracellularly MetalIogenium-like particles similar to those which are often detected in the chemocline of lakes. This suggested that the naturally occurring Metallogenium-like particles originated in ac- tivities of such heterotrophic manganese-oxidizing bac- teria. The manganese oxidation activity usually appeared only at the stationary phase of bacterial growth. The oxidation of Mn 2 + and the formation of Metallogenium- like particles by the bacteria were observed at neutral or slightly acidic pH, not under alkaline conditions, which is a conspicuous difference from the inorganic oxidation of Mn 2+ by O2. Bacterial manganese oxidation was stimulated by bicarbonate (50 or 500 gM). An experiment of addition of H202 to the incubation tubes isolated from atmosphere failed to confirm the availability of externally added H202 as the electron acceptor, suggesting that the bacterial manganese oxidation required the presence of O 2 .

Role of bacterial plasmids in manganese oxidation: Evidence for plasmid‐encoded heavy metal resistance

Abstract Forty‐seven manganese‐oxidizing bacterial strains, isolated from manganese nodules, sediment, and sea‐water samples collected from the Pacific Ocean and the Mediterranean Sea, were studied to elucidate the role, if any, of plasmids in bacterial manganese oxidation in the marine environment. Twenty‐two strains of Pseudomonas and seven unidentified species were found to harbor single plasmids. Seven of the plasmid‐containing Pseudomonas spp. and one of the unidentified strains were selected for curing. Only Pseudomonas strain 57, originally isolated from a manganese nodule collected from the Pacific Ocean, was cured successfully. This strain carried a plasmid (pZPl) of about 9 Mdal, and demonstrated enzymatic oxidation of manganese. Although the function ascribable to pZPl remains cryptic, evidence obtained from the study of Pseudomonas strain 57 (carrying pZPl) and its cured derivative suggests that the plasmid encodes resistance to manganese and copper. It is hypothesized that the plasmid (pZPl) ...

Determination of bacterial manganese oxidation rates in sediments using an in-situ dialysis technique I. Laboratory studies

An in-situ dialysis technique has been developed to examine chemical and bacterial rates of manganese binding and oxidation under diffusion-limited conditions in sediments. With this method, the microbial and abiotic components of manganese binding were delineated quantitatively in laboratory sediments spiked with manganese oxidizing bacteria. The abiotic removal of manganese by the same sediments has also been determined independently to define the relative importance of adsorption, ion exchange and autocatalytic oxidation in the removal of Mn 2+ from solution. Independent measurements of both bacterial and abiotic manganese binding were in good agreement with the diffusion-controlled rate data, validating the use of this dialysis technique as a means of examining manganese oxidation in-situ.

Surface enhancement of bacterial manganese oxidation: Implications for aquatic environments

The manganese‐precipitating activities of a marine bacillus (strain SG‐1) are enhanced by interaction with solid surfaces. When not attached to surfaces, SG‐1 exhibits little or no ability to oxidize manganese. After the bacteria attach to any of a variety of surfaces (e.g., glass beads, frosted glass, sand grains; and calcite crystals), manganese is rapidly precipitated and removed from solution. Attached and manganese‐precipitating cells are morphologically distinct from free‐swimming or non‐precipitating cells.