Publications by authors named "Larissa B Folman"

5 Publications

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Mechanism of antibacterial activity of the white-rot fungus Hypholoma fasciculare colonizing wood.

Can J Microbiol 2010 May;56(5):380-8

Netherlands Institute of Ecology (NIOO-KNAW), Department of Microbial Ecology, Boterhoeksestraat 48, Heteren 6666 GA, Netherlands.

In a previous study it was shown that the number of wood-inhabiting bacteria was drastically reduced after colonization of beech (Fagus sylvatica) wood blocks by the white-rot fungus Hypholoma fasciculare, or sulfur tuft (Folman et al. 2008). Here we report on the mechanisms of this fungal-induced antibacterial activity. Hypholoma fasciculare was allowed to invade beech and pine (Pinus sylvestris) wood blocks that had been precolonized by microorganisms from forest soil. The changes in the number of bacteria, fungal biomass, and fungal-related wood properties were followed for 23 weeks. Colonization by the fungus resulted in a rapid and large reduction in the number of bacteria (colony-forming units), which was already apparent after 4 weeks of incubation. The reduction in the number of bacteria coincided with fungal-induced acidification in both beech and pine wood blocks. No evidence was found for the involvement of toxic secondary metabolites or reactive oxygen species in the reduction of the number of bacteria. Additional experiments showed that the dominant bacteria present in the wood blocks were not able to grow under the acidic conditions (pH 3.5) created by the fungus. Hence our research pointed at rapid acidification as the major factor causing reduction of wood-inhabiting bacteria upon colonization of wood by H. fasciculare.
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http://dx.doi.org/10.1139/w10-023DOI Listing
May 2010

Methylovirgula ligni gen. nov., sp. nov., an obligately acidophilic, facultatively methylotrophic bacterium with a highly divergent mxaF gene.

Int J Syst Evol Microbiol 2009 Oct 21;59(Pt 10):2538-45. Epub 2009 Jul 21.

S. N. Winogradsky Institute of Microbiology, Russian Academy of Sciences, Moscow 117312, Russia.

Two strains of Gram-negative, aerobic, non-pigmented, non-motile, rod-shaped bacteria were isolated from beechwood blocks during decay by the white-rot fungus Hypholoma fasciculare and were designated strains BW863(T) and BW872. They are capable of methylotrophic growth and assimilate carbon via the ribulose-bisphosphate pathway. In addition to methanol, the novel isolates utilized ethanol, pyruvate and malate. Strains BW863(T) and BW872 are obligately acidophilic, mesophilic organisms capable of growth at pH 3.1-6.5 (with an optimum at pH 4.5-5.0) and at 4-30 degrees C. Phospholipid fatty acid profiles of these bacteria contain unusually large amounts (about 90 %) of C(18 : 1)omega7c, thereby resembling the profiles of Methylobacterium strains. The predominant quinone is Q-10. The DNA G+C content of the novel isolates is 61.8-62.8 mol%. On the basis of 16S rRNA gene sequence similarity, strains BW863(T) and BW872 are most closely related to the acidophilic methanotroph Methylocapsa acidiphila B2(T) (96.5-97 %). Comparative sequence analysis of mxaF, the gene encoding the large subunit of methanol dehydrogenase, placed the MxaF sequences of the two novel strains in a cluster that is distinct from all previously described MxaF sequences of cultivated methylotrophs. The identity between the MxaF sequences of the acidophilic isolates and those from known alpha-, beta- and gammaproteobacterial methylotrophs was respectively 69-75, 61-63 and 64-67 %. The data therefore suggest that strains BW863(T) and BW872 represent a novel genus and species of methylotrophic bacteria, for which the name Methylovirgula ligni gen. nov., sp. nov. is proposed. Strain BW863(T) (=DSM 19998(T) =NCIMB 14408(T)) is the type strain of Methylovirgula ligni.
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http://dx.doi.org/10.1099/ijs.0.010074-0DOI Listing
October 2009

Impact of white-rot fungi on numbers and community composition of bacteria colonizing beech wood from forest soil.

FEMS Microbiol Ecol 2008 Feb;63(2):181-91

Department of Plant Microorganism Interactions, NIOO-Centre for Terrestrial Ecology, ZG Heteren, The Netherlands.

White-rot fungi are important wood-decomposing organisms in forest ecosystems. Their ability to colonize and decompose woody resources may be strongly influenced by wood-inhabiting bacteria that grow on easily utilizable compounds e.g. oligomers of wood-polymers released by fungal enzymes. However, so far, it is not known how white-rot fungi deal with the presence of potential competing bacteria. Here, the effects of two white-rot fungi, Hypholoma fasciculare and Resinicium bicolor, on the numbers and composition of bacteria colonizing sterile beech wood blocks from forest soil are reported. Both total numbers (microscopic counts) and the numbers of cultivable wood-inhabiting bacteria were considerably lower in wood blocks that became colonized by the white-rot fungi than in control blocks. This points to the fungi out-competing the opportunistic bacteria. The presence of white-rot fungi resulted in a change in the relative abundance of families of cultivable bacteria in wood and also in a change of denaturing gradient gel electrophoresis patterns of directly amplified 16S rRNA gene fragments. Analysis of the bacterial community structure in soil adhering to exploratory mycelium (cords) indicated that fungal species-specific effects on bacterial community composition were also apparent in this fungal growth phase.
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http://dx.doi.org/10.1111/j.1574-6941.2007.00425.xDOI Listing
February 2008

Living in a fungal world: impact of fungi on soil bacterial niche development.

FEMS Microbiol Rev 2005 Sep 16;29(4):795-811. Epub 2004 Dec 16.

NIOO-Centre for Terrestrial Ecology, Department of Plant Microorganism Interactions, Heteren, The Netherlands.

The colonization of land by plants appears to have coincided with the appearance of mycorrhiza-like fungi. Over evolutionary time, fungi have maintained their prominent role in the formation of mycorrhizal associations. In addition, however, they have been able to occupy other terrestrial niches of which the decomposition of recalcitrant organic matter is perhaps the most remarkable. This implies that, in contrast to that of aquatic organic matter decomposition, bacteria have not been able to monopolize decomposition processes in terrestrial ecosystems. The emergence of fungi in terrestrial ecosystems must have had a strong impact on the evolution of terrestrial bacteria. On the one hand, potential decomposition niches, e.g. lignin degradation, have been lost for bacteria, whereas on the other hand the presence of fungi has itself created new bacterial niches. Confrontation between bacteria and fungi is ongoing, and from studying contemporary interactions, we can learn about the impact that fungi presently have, and have had in the past, on the ecology and evolution of terrestrial bacteria. In the first part of this review, the focus is on niche differentiation between soil bacteria and fungi involved in the decomposition of plant-derived organic matter. Bacteria and fungi are seen to compete for simple plant-derived substrates and have developed antagonistic strategies. For more recalcitrant organic substrates, e.g. cellulose and lignin, both competitive and mutualistic strategies appear to have evolved. In the second part of the review, bacterial niches with respect to the utilization of fungal-derived substrates are considered. Here, several lines of development can be recognized, ranging from mutualistic exudate-consuming bacteria that are associated with fungal surfaces to endosymbiotic and mycophagous bacteria. In some cases, there are indications of fungal specific selection in fungus-associated bacteria, and possible mechanisms for such selection are discussed.
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http://dx.doi.org/10.1016/j.femsre.2004.11.005DOI Listing
September 2005

Characterisation of Lysobacter enzymogenes (Christensen and Cook 1978) strain 3.1T8, a powerful antagonist of fungal diseases of cucumber.

Microbiol Res 2003 ;158(2):107-15

Institute of Evolutionary and Ecological Sciences, University of Leiden, P.O. Box 9516, 2300 RA Leiden, The Netherlands.

Isolate 3.1T8 of Lysobacter enzymogenes (Christensen and Cook 1978), originating from the rhizosphere of cucumber and shown to have the potential to control Pythium aphanidermatum, is described. The strain produces extracellular proteases and lipases and shows high levels of resistance against streptomycin, kanamycin and tetracycline, but not to chloramphenicol. It shows strong in vitro antibiosis against P. aphanidermatum and several other phytopathogenic fungi. In order to identify the isolate, a carbon substrate oxidation profile (Biolog) was generated, and fatty acid methyl ester (FAME) analysis was performed. Also, the 16S rRNA gene was cloned and sequenced. With Biolog and FAME analysis, no assignment to species level was possible, because the species was not in the respective databases. BLAST analysis of the obtained sequence, followed by phylogenetic analysis, using a number of related and unrelated sequences, showed that the isolate was most closely related to Lysobacter enzymogenes (Christensen and Cook 1978).
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http://dx.doi.org/10.1078/0944-5013-00185DOI Listing
September 2003