Natural Attenuation of Mn(II) in Metal Refinery Wastewater: Microbial Community Structure Analysis and Isolation of a New Mn(II)-Oxidizing Bacterium Pseudomonas sp. SK3

Abstract

Natural attenuation of Mn(II) was observed inside the metal refinery wastewater pipeline, accompanying dark brown-colored mineralization (mostly MnIVO2 with some MnIII2O3 and Fe2O3) on the inner pipe surface. The Mn-deposit hosted the bacterial community comprised of Hyphomicrobium sp. (22.1%), Magnetospirillum sp. (3.2%), Geobacter sp. (0.3%), Bacillus sp. (0.18%), Pseudomonas sp. (0.03%), and non-metal-metabolizing bacteria (74.2%). Culture enrichment of the Mn-deposit led to the isolation of a new heterotrophic Mn(II)-oxidizer Pseudomonas sp. SK3, with its closest relative Ps. resinovorans (with 98.4% 16S rRNA gene sequence identity), which was previously unknown as an Mn(II)-oxidizer. Oxidation of up to 100 mg/L Mn(II) was readily initiated and completed by isolate SK3, even in the presence of high contents of MgSO4 (a typical solute in metal refinery wastewaters). Additional Cu(II) facilitated Mn(II) oxidation by isolate SK3 (implying the involvement of multicopper oxidase enzyme), allowing a 2-fold greater Mn removal rate, compared to the well-studied Mn(II)-oxidizer Ps. putida MnB1. Poorly crystalline biogenic birnessite was formed by isolate SK3 via one-electron transfer oxidation, gradually raising the Mn AOS (average oxidation state) to 3.80 in 72 h. Together with its efficient in vitro Mn(II) oxidation behavior, a high Mn AOS level of 3.75 was observed with the pipeline Mn-deposit sample collected in situ. The overall results, including the microbial community structure analysis of the pipeline sample, suggest that the natural Mn(II) attenuation phenomenon was characterized by robust in situ activity of Mn(II) oxidizers (including strain SK3) for continuous generation of Mn(IV). This likely synergistically facilitated chemical Mn(II)/Mn(IV) synproportionation for effective Mn removal in the complex ecosystem established in this artificial pipeline structure. The potential utility of isolate SK3 is illustrated for further industrial application in metal refinery wastewater treatment processes.

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

“…MOB are ubiquitous in nature and can be isolated from different habitats. 32,40 Among the most studied genera are Leptothrix, Hyphomicrobium, Crenothrix, Siderocapsa, Siderocystic, Metallogenium, 16,18,20,32 Bacillus, 31,41 Pseudomonas 42,43 and Pedomicrobium. 44 Therefore, there is a great opportunity for the application of biofiltration for manganese removal; however, the establishment of active biofilms in biofilters can take several months.…”

Adaptive Evolution of Geobacter sulfurreducens in Coculture with Pseudomonas aeruginosa

“…are often less abundant than Geobacter spp. (33,35,37), we believe that their coculture interaction dynamics observed in this study may have ecological relevance. This study provides the first account for selection of tetR and fabI mutations in Geobacter spp.…”

“…Geobacter and Pseudomonas spp. are electrochemically active bacteria found to cohabit many of the same environments of ecological significance, including contaminated sites and wastewater streams (35,38). In this study, assessment of their adaptive evolution using serial transfers in vitro enabled observations of real-time interaction dynamics and survival strategies, something not easily acquired through in situ experiments given the complexity of their environments and the presence of other community members.…”

“…phenazines are also known for their antibiotic properties, as are a multitude of other molecules they secrete (31,32). P. aeruginosa and G. sulfurreducens have been found to coexist in many of the same environments, such as salt marsh estuaries, aquatic sediments, wastewater, and contaminated groundwater (33)(34)(35)(36)(37)(38). Their potential for interaction, however, has only recently been investigated.…”

Simultaneous Arsenic and Iron Oxidation for One-Step Scorodite Crystallization Using Mn Oxide

“…SK3 cells were able to complete the oxidation of this amount of Mn 2+ . 33) Biogenic birnessite itself could lead to autocatalytic, chemical Mn 2+ oxidation by the comproportionation of Mn 2+ and MnO 2 , especially in alkaline conditions (eq. ( 6)).…”