Metal reduction at cold temperatures by Shewanella isolates from various marine environments

Abstract

Members of the genus Shewanella capable of reducing metals and forming minerals under cold-temperature conditions were isolated from 3 distinct marine habitats (the coast of Washington State, the Puget Sound, and an iron-rich microbial mat off Hawaii). Cultures of microorganisms were isolated at 8°C on nutrient agar medium prepared in artificial seawater. Isolates in this study could use a wide variety of electron acceptors such as oxygen, nitrate, and metals, and reduce various metals coupled to the oxidation of several organic acids, glucose or hydrogen at temperatures down to 0°C. Akaganeite was reduced to either magnetite or siderite, depending on the test conditions. The geochemical profiles at the sample sites from which these strains were isolated spanned a temperature range of 1.8 to 11°C, and all showed active oxygen and nitrate reduction as well as metal reduction. This confirms previous reports that sediment microorganisms participating in biogeochemical cycles remain active at low temperatures. KEY WORDS: Biogeochemistry · Geomicrobiology · Iron reduction · Cobalt reduction · Magneite Resale or republication not permitted without written consent of the publisherAquat Microb Ecol 38: [81][82][83][84][85][86][87][88][89][90][91] 2005 While their quantitative importance in marine sediments and water columns is not well understood, members of the genus Shewanella are commonly encountered in marine environments (Perry et al. 1993, Thamdrup et al. 2000, Brettar et al. 2002. These isolates have provided useful models for laboratory investigations on metal reduction (Nealson & Saffarini 1994, Kostka & Nealson 1995, food spoilage, barophilic growth (Kato & Nogi 2001) and, more recently, psychrophilic enzymes (Irwin et al. 2001a,b). The present study describes the isolation of members of the genus Shewanella from 3 marine environments. Specifically, strains W3-6-1 and PS-7 were used as models to investigate microbial metal reduction and mineral formation at low temperatures. MATERIALS AND METHODSSite description and sampling. Marine sediment samples were collected from a transect off the coast of Washington State (USA), at 2 locations in Puget Sound (USA) and from an iron-rich microbial mat associated with the Naha Vents on the South Rift of Loihi Seamount near Hawaii. With the exception of the vent sites, sediments were collected by box core sampling. The microbial mat sample was collected during DSRV Pisces V dive number 342 (Emerson & Moyer 2002). Each box core was sub-cored for sectioning using 7.5 and 10 cm cast-acrylic core tubes. Core sectioning took place within approximately 1 h of coring in a glove-box at ~5°C in a N 2 atmosphere. Cores were stored at ~5°C to minimize effects due to warming. Details of sample location, including geographic coordinates, are listed in Table 1.The geochemistry of the sediments was inferred from sediment pore-water distributions. Pore-water was separated from the sediments by centrifugation at 7000 rpm (>10 000 × g) for 20 min; supernatants were filtered thr...

Extracellular respiration of dimethyl sulfoxide by Shewanella oneidensis strain MR-1

“…S. oneidensis was isolated from Oneida Lake in upstate New York (30), which completely freezes over during the winter months (31). Moreover, S. oneidensis has recently been shown to have the capacity to grow aerobically at low temperatures (32), similar to many other Shewanella species (2,33,34). We determined that S. oneidensis could grow anaerobically at 4°C with DMSO, showing only residual growth with no electron acceptor added (Fig.…”

Metal Reduction and Iron Biomineralization by a Psychrotolerant Fe(III)-Reducing Bacterium, Shewanella sp. Strain PV-4

“…When the microbial mat samples were collected, the in situ water temperature at the vent was 11°C, and the ambient seawater temperature was 4°C. Sample collection, handling, bacterial enrichments, and isolation were described previously (33). The small-subunit rRNA gene of strain PV-4 was sequenced to determine phylogeny (33).…”

“…We have previously isolated more than 10 Shewanella strains from a variety of marine environments (33). Strain PV-4, isolated from iron-rich microbial mats at an active, deep-sea, hydrothermal Naha vent of Loihi Seamount, Hawaii, is the first Shewanella strain capable of reducing metals in a wide range of temperatures, from 0 to 37°C.…”

Shewanella loihica sp. nov., isolated from iron-rich microbial mats in the Pacific Ocean

“…In a previous study, several Shewanella strains were isolated from marine-sediment samples at a variety of locations in the Pacific Ocean (Stapleton et al, 2005). Among these…”

“…shewanella.org). Some Shewanella strains are also able to degrade pollutants such as chlorinated solvents (Petrovskis et al, 1994), petroleum (Semple & Westlake, 1987) and RDX (1,3,5-trinitroperhydro-1,3,5-triazine) (Zhao et al, 2004), some can produce polyunsaturated fatty acids (Bowman et al, 1997;Russell & Nichols, 1999;Satomi et al, 2003) and some are able to grow under extreme conditions (Bozal et al, 2002;Kato et al, 1998;Nogi et al, 1998;Stapleton et al, 2005).…”