The bacterial population of a blanket peat

Abstract

The number of aerobic bacteria in a blanket peat decreased with depth from 26 times 106/g dry peat in the surface layers to 0.5 times 106/g dry peat at 30–40 cm down the profile, thereafter remaining roughly constant. Obligate psychrophiles comprised <2.5% of this population. Anaerobes were most numerous, 9 times 106/g dry peat at 6–10 cm depth, decreasing to 0.5 times 106/g at 20–30 cm. Calculations indicated that these counts, 103–104‐fold lower than the direct counts, substantially underestimated the active microbial population. Gram negative rods, the predominant aerobes in the surface layers, were replaced by unidentified Bacillus strains at 10–20 cm depth but became increasingly more numerous further down the profile. The Gram negative rods were the most numerous organisms/m2 but the Bacillus strains, one third of which were present as spores, made the largest contribution to the biomass/m2. Gram positive cocci, Arthrobacter and, infrequently, Nocardia were also isolated. Actinomyces‐like forms were the predominant obligate anaerobes and were approximately three times more numerous than clostridia and a curved Gram negative rod.

Differences in Microbial Activity and Microbial Populations of Peat Associated with Suppression of Damping-Off Disease Caused by Pythium sylvaticum

“…The mean level of bacterial counts recovered by plating from these samples was lower than that previously reported (16,17,35); however, bacterial counts were positively correlated with the moisture contents of the peats, and the low levels may reflect the low moisture contents of some peats. The fact that neither bacterial nor fungal counts were correlated with the level of damping-off suggests that changes in the composition of microbial populations may be more important in disease suppression than gross changes in the number of microorganisms present.…”

Vacuum-extraction of peatlands disturbs bacterial population and microbial biomass carbon

“…The aerobic bacterial population of all peatland sites and types confounded were similar to those observed by Waksman and Stevens (1929), Waksman and Purvis (1932), Collins et al (1978) and Martin et al (1982) in natural ombrotrophic peatlands. Bacterial counts between log 10 5.5 to 7.7 g −1 (dw) are common in peatland surface of bogs (Given and Dickinson, 1975).…”

“…Similarly, Dooley and Dickinson (1970) obtained no increase in microflora species in a complex of ombrotrophic peatlands exploited and abandoned for 10 years. Most microorganisms isolated in this study are ubiquitous in peatland (Ivarson, 1977;Collins et al, 1978;Martin et al, 1982;Tahvonen, 1982). Also, they are related to the carbon cycle such as pectinic substances, cellulose, hemicellulose or lignin decomposition.…”

“…Also, among the isolated actinomycetes, only Micrococcus luteus was exclusive to the natural peatland. However, M. luteus has been isolated from several habitats such as skin, soil, plants and water (Balows et al, 1992), and peatlands (Martin et al, 1982;Collins et al, 1978). Again, this microorganism was not considered as potential bio-indicator.…”

The molecular diversity of the methanogenic community in a hypereutrophic freshwater lake determined by PCR-RFLP

“…Development of methods for analysing methanogenic Archaea, within complex environments such as freshwater lakes is therefore of fundamental importance. Ecological studies of methanogens have previously used traditional culture-based techniques such as anaerobic cell culture, electron microscopy and autofluorescence microscopy (Martin et al 1982;Dolfing et al 1985;Franklin et al 1988). More recently, molecular biological methods involving 16S rRNA gene sequence analysis have been applied to investigate methanogen communities in a wide range of environments from rice paddy fields (Kudo et al 1997;Grosskopf et al 1998;Weber et al 2001), anaerobic digestors (Raskin et al 1994a,b), extreme environments (DeLong 1998;Marchesi et al 2001), marine sediments (DeLong 1992) and the digestive tracts of living organisms (Stahl et al 1988;Finlay et al 1994;Sharp et al 1998;Tajima et al 2001).…”