Environmental Bacteria Involved in Manganese(II) Oxidation and Removal From Groundwater

Abstract

The presence of iron (Fe) and manganese (Mn) in groundwater is an important concern in populations that use it as source of drinking water. The ingestion of high concentrations of these metals may affect human health. In addition, these metals cause aesthetic and organoleptic problems that affect water quality and also induce corrosion in distribution networks, generating operational and system maintenance problems. Biological sand filter systems are widely used to remove Fe and Mn from groundwater since they are a cost-effective technology and minimize the use of chemical oxidants. In this work, the bacterial communities of two biological water treatment plants from Argentina, exposed to long term presence of Mn(II) and with a high Mn(II) removal efficiency, were characterized using 16S rRNA gene Illumina sequencing. Several selective media were used to culture Mn-oxidizing bacteria (MOB) and a large number of known MOB and several isolates that have never been reported before as MOB were cultivated. These bacteria were characterized to select those with the highest Mn(II) oxidation and biofilm formation capacities and also those that can oxidize Mn(II) at different environmental growth conditions. In addition, studies were performed to determine if the selected MOB were able to oxidize Mn(II) present in groundwater while immobilized on sand. This work allowed the isolation of several bacterial strains adequate to develop an inoculum applicable to improve Mn(II) removal efficiency of sand filter water treatment plants.

Autochthonous tropical groundwater bacteria involved in manganese(ii) oxidation and removal

“…These results are in agreement with previous findings for different MOB than the ones reported here, suggesting that during the stationary phase biological oxidation of Mn(II) takes place. 25,35,[66][67][68][69][70][71][72] In the second group of strains (HAC-3A, HAC-3B and RUE-6A), Fig. 2A, no further Mn(II) removal took place after the second day.…”

“…30,33 Moreover, they are catalytic agents for secondary oxidation reactions of Mn(II) that depend on Mn(II) concentration, temperature and other ions, among others. 32 Furthermore, the biofilm formation capacity of Mn oxidizing bacteria (MOB) immobilizes them in the filter material, 34,35 through their EPS matrix, and thus tolerates the environmental and mechanical conditions of the biofilters 27,28 and contributes to the adsorption of metals. 26,[36][37][38][39] Biological removal of Mn can be carried out by: 7,32 (a) direct oxidation, through intracellular oxidation of Mn(II) as part of the metabolic pathway of the microorganism; (b) indirect oxidation as a result of a change of the surrounding aqueous environment (pH and redox potential) and/or by the release of metabolic end products that favour the chemical oxidation of Mn(II); (c) extracellular adsorption of Mn on negatively charged EPS, as well as on biogenic oxides formed by bacterial catalytic reactions.…”

“…9,45 For this reason, the study of MOB for the development of inoculums that contribute to reducing the start-up time of biofilters is of interest. 29,35,46,47 Examples of proactive inoculation methods, listed by Breda et al, 47 include the addition of a concentrated source of microorganisms and/or catalytic surfaces like backwash sludge, matured filter sand, mixed culture bacteria or specific bacterial species. A different approach consists of the use of the indigenous bacteria present in well water containing manganese.…”

Complete genome sequence of plant growth‐promoting and heavy metal‐tolerant Enterobacter tabaci 4M9 (CCB‐MBL 5004)

“…Mn is mainly present in reduced forms and their removal is mostly based on chemical oxidation that could be performed through induction of the oxidation of these metals to form insoluble oxides or the addition of strong oxidizing agents [39,40]. Manganese‐tolerant PGPR could be used to decrease the concentration and effects of this metal from contaminated sites in an environmental‐friendly manner, thereby improving the growth and health of the host plants.…”

Mechanism of manganese oxidization of Bacillus safensis strain ST7 isolated from the soil of mineral area

“…And manganese pollution in a low concentration need microorganism to remove thoroughly. Many kinds of bacteria can transform thoroughly the Mn(II) to its oxides [11]. It is reported that kinds of manganese-oxidizing bacteria (MOB) harbour multicopper oxidase (MCO)-type enzyme or heme peroxidase [12,13] with the capacity of oxidization the soluble Mn(II) to insoluble Mn(IV).…”