Role of organic acids in the mechanisms of biological soil disinfestation (BSD)

Proliferation of diversified clostridial species during biological soil disinfestation incorporated with plant biomass under various conditions

“…It has been pointed out that accumulation of VFAs such as acetate and butyrate would be the important factors for killing the plant pathogens during the process of disinfestation (Momma et al 2006). In our study, rather high amounts of acetate were detected from all BSD soil samples together with butyrate especially for the wheat bran-treated soils, while no VFAs was detected from the control soils.…”

“…The members in the class Clostridia are known to produce some harmful compounds to pathogens, such as skatole, indole, cresol or some phenolic compounds, by the fermentation of amino acids such as tryptophan and tyrosine under anaerobic conditions (Macfarlane and Macfarlane 1995). Besides, fatty acids like acetate or butyrate produced by these bacterial groups were supposed to contribute to pathogen inactivation (Momma et al 2006). These acids were actually detected in the BSD soil (Mowlick et al 2012), and it was strongly suggested that acetate, butyrate or other substances could be the products of the clostridial groups responsible for the suppression of some soil borne pathogens.…”

Biological Soil Disinfestation (BSD) of Soilborne Pathogens and Its Possible Mechanisms

“…When the soil without wheat bran was irrigated and the pots were sealed, the pathogen decreased to 8.0 × 10 4 CUF/g dry soil. In the case of Ralstonia solanacearum EK1-2 (biovar 4, race 1), the causal agent of bacterial wilt of tomato, when 250 g of infested soil in a glass bottle was treated with BSD using 4 g of wheat bran, population of the pathogen decreased below the detection limit 14 days after treatment 9 . No colony was formed even when a portion of BSD-treated soil was directly spread onto selective media in both cases.…”

“…Acetic acid and n-butyric acid were detected in BSDtreated soil by HPLC analysis 9 . Acetic acid accumulated at 2,100 mg/kg dry soil and butyric acid at 1,800 mg/kg dry soil, 15 and 6 days after treatment, respectively.…”

Nematicidal activity of volatile fatty acids generated from wheat bran in reductive soil disinfestation

“…Therefore, VFAs generation is suggested to be a factor in the mechanism of RSD in practice. Momma et al (2006) also showed that VFAs are factors contributing to suppression of soil-borne pathogens by RSD. Volatile fatty acids have long been known for their nematicidal effects (Stephenson, 1945;Johnston, 1959;Banage and Visser, 1965;Nagase et al, 1982;Bansal and Bajaj, 2003;Browning et al, 2004;McElderry et al, 2005) and noted as a group of naturally occurring chemicals during decomposition (Sayre et al, 1965;Hollis and RodriguezKabana, 1966;Elmiligy and Norton, 1973;Lynch, 1978;Badra et al, 1979;Djian et al, 1991;McBride et al, 2000;Chitwood, 2002).…”