Lactic acid bacteria in organic agricultural soils

E. Somers, A. Amke, A. Croonenborghs, L.S. van Overbeek, J. Vanderleyden

    Research output: Contribution to conferencePosterProfessional

    Abstract

    According to a concept formulated by H.P. Rusch (1906-1977), soil fertility of organic agricultural soils can be related to the presence of lactic acid bacteria. However, there is little or no evidence in literature to support this concept. We have sampled at different time points over a 2 year period (2005-2006) 15 organic farms in Flanders. Soils used for the organic production of cabbage and leak were sampled. Direct plating of soil dilutions on either MRS (with glucose as carbon source) or M17 (with lactose as carbon), commonly used growth media for lactic acid bacteria, revealed no significant numbers of lactic acid bacteria. The same results were obtained with the culture independent DGGE analysis, using nested PCR as described by Heilig et al. (2002). Identification of colonies obtained by direct plating using Lactobacillus group-specific primers for 16S rDNA sequences indicated mainly Bacillus, Paenibacillus and Staphylococcus species. In a second round, an enrichment step for lactic acid bacteria was included, by incubating diluted soil samples anaerobically in MRS or M17 medium, prior to plating or DGGE analysis, as described by Chen et al (2005). This revealed high numbers and diversity of lactic acid bacteria. Sequencing the 16S rDNA revealed the following lactic acid bacteria: Lactococcus garvieae, Lactococcus lactis, Leuconostoc mesenteroides, Weissella, Lactobacillus and Enterococcus. Some of these isolates were tested and found positive for biocontrol activity and/or direct plant growth promotion. Two Lactococcus lactis isolates showed significant plant growth promoting activity in greenhouse trials with cabbage. It can be concluded that lactic acid bacteria, although present, are not dominant in organic farming soils in Flanders. Nevertheless, if they can be enriched through agricultural practices, some of these show potential for biocontrol and/or plant growth promotion
    Original languageEnglish
    Publication statusPublished - 2007
    EventRhizosphere 2 - Montpellier, France
    Duration: 26 Aug 200731 Aug 2007

    Conference

    ConferenceRhizosphere 2
    CountryFrance
    CityMontpellier
    Period26/08/0731/08/07

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