摘要:

Manganese is oxidized by a wide variety of bacteria. The current state of knowledge on mechanisms and functions of Mn2+oxidation in two strains ofPseudomonas putida, inLeptothrix discophoraSS-1, and inBacillussp. strain SG-1 is reviewed. In all three species, proteins bearing resemblance to multicopper oxidases appear to be involved in the oxidation process. A short description of the classification of Cu centers is followed by a more detailed review of properties and postulated functions of some well-known multicopper oxidases. Finally, suggestions are made for future research to assess the potential role of multicopper oxidases in bacterial Mn2+oxidation.

ISSN:0149-0451    

DOI:10.1080/014904500270459

出版商:Informa UK Ltd    

年代:2000

数据来源: Taylor

摘要:

The effect of Cu2+on the Mn2+-oxidizing activity secreted byLeptothrix discophorastrain SS-1 was studied. Cu2+stimulated the activity of spent medium from stationary cultures when added during growth of the bacteria, although cell yield decreased with increasing Cu2+concentrations. The stimulation was tentatively explained by involvement of the putative multicopper oxidase MofA in Mn2+oxidation. Cu2+did not enhance the activity when added directly to spent medium, possibly because the ions had to be incorporated during synthesis of the oxidizing factor. Sequence analysis of the region downstream from themofAgene resulted in identification ofmofB, which encodes a protein with a potential peptidyl-prolyl-cis-transisomerase site, andmofC, which encodes a protein with a potential heme-binding site. The possibility thatmofA,mofB, andmofCbelong to one operon, and the possible functions of MofB and MofC, are discussed.

ISSN:0149-0451    

DOI:10.1080/014904500270468

出版商:Informa UK Ltd    

年代:2000

数据来源: Taylor

摘要:

Copper dissolution from a sulfide ore (with covellite as the main copper phase) was investigated in cultures ofThiobacillus ferrooxidansorThiobacillus thiooxidansand in abiotic controls. In unsupplemented media,T. ferrooxidanswas more efficient thanT. thiooxidans. In the presence of ferric iron, the dissolution of covellite was not significantly different in cultures inoculated withT. ferrooxidansorT. thiooxidans. However, the most extraction was found inT. thiooxidanscultures supplemented with ferrous sulfate. The first results were explained by the mechanism proposed by Schippers and Sand (Appl Envir Microbiol 65:319-321, 1999), which involves polysulfides and sulfur as intermediates. This mechanism was extended to explain the behavior ofT. thiooxidansculture supplemented with ferrous iron.

ISSN:0149-0451    

DOI:10.1080/014904500270477

出版商:Informa UK Ltd    

年代:2000

数据来源: Taylor

摘要:

Secondary minerals near and within fractures in Columbia River basalts contain objects the size and shape of bacteria. These bacteriomorphs are most commonly rods or ellipses but also include cocci and diplococci forms, vibrioids and club-shaped rods, and associated pairs of objects that suggest cellular division by binary fission. Secondary minerals associated with, enclosing, and making up bacteriomorphs include iron oxyhydroxides, sulfides, and smectites containing ferrous iron. The secondary minerals are intimately intermixed with kerogen. Moreover, bacteriomorphs in the pyrite consist of kerogen. Careful consideration of mineral associations, the occurrence of organic carbon, and the spatial context of bacteriomorphs indicate that they are microfossils. The association of microfossils with minerals formed in reducing environments suggests an ancient ecosystem dominated at least in part by sulfate-reducing bacteria, similar to communities within these basalts today.

ISSN:0149-0451    

DOI:10.1080/014904500270486

出版商:Informa UK Ltd    

年代:2000

数据来源: Taylor

摘要:

The biodeterioration of granite byLecidea fuscoatra(L.) Ach.,Porpidia cinereoatra(Ach.) Hertel & Knoph, andP. macrocarpa(DC.) Hertel & Schwab growing in the same environmental conditions has been studied by using Fourier transform-Raman spectroscopy. Results were significantly different for the three species, withP. cinereoatrabeing the most active biodeteriorative lichen. This lichen was also the only one in which calcium oxalate and gypsum were identified spectroscopically. Physical disturbances to the substratum were evidenced in all lichens studied by the incoporation of material, such as quartz and feldspar, into their thalli, but this phenomenon varied considerably from species to species. The results indicate that lichen species can adopt different strategies and can have different biodeteriorative effects on granite, independently of environmental conditions and substrate.

ISSN:0149-0451    

DOI:10.1080/014904500270495

出版商:Informa UK Ltd    

年代:2000

数据来源: Taylor

摘要:

We examined controls on mineralization of carbon to methane (CH4) and carbon dioxide (CO2) inSphagnum(moss)-dominated peatland ecosystems by transplanting surface (5 cm deep) and subsurface (40 cm deep) peat samples reciprocally among three sites for periods ranging from 4 to 25 months. The sites were Big Run Bog in West Virginia, USA, Bog Lake Bog in Minnesota, USA, and Bog 307 in Ontario, Canada. Immediately upon retrieval, we incubated the peat samples in the laboratory at 12 and 22°C under both anoxic and oxic conditions to estimate rates of carbon mineralization. Transplanting affected surface peat more than subsurface peat. Peat incubated within Bog Lake Bog in Minnesota had the highest rates of CH4production, regardless of origin, whereas transplanting did not affect rates of CO2production measured concomitantly. Peat that originated in Big Run Bog in West Virginia generally maintained higher rates of CH4production and CO2production than peat from the other two sites after incubation in the field. The temperature dependence (Q10) of CH4production and CO2production varied among transplant sites, but not among peat origins, suggesting physiological adaptations of microbial communities to local environmental conditions. Differences in organic matter quality of the peat, particularly lignin chemistry, helped explain the results: (a) CH4production correlated with fresher lignin derived fromCarexsedges, and (b) CO2production correlated with woody lignin. We concluded that, although both site conditions (climate, nutrient status, and microbial communities) and organic matter quality influence carbon mineralization in peat, interactive effects occur and may differ depending on peat temperature. Moreover, CH4production and CO2production respond differently to environmental regulators.

ISSN:0149-0451    

DOI:10.1080/014904500270503

出版商:Informa UK Ltd    

年代:2000

数据来源: Taylor

ISSN:0149-0451    

DOI:10.1080/014904500270512

出版商:Informa UK Ltd    

年代:2000

数据来源: Taylor