Hydroxybenzoate, microbial inhibition

Plants contain shikimate dehydrogenase (shikimate NADP oxidoreduc-tase) which reversibly interconverts dehydroshikimate and shikimate [Fig. 2 (4)]. The enzyme has been detected in a number of plant sources (Balinsky and Davies, l%la Yoshida, 1969). Unlike the microbial enzyme which is specific for NAD, the plant enzyme is specific for NADP (Balinsky and Davies, 1961b). Anthranilic acid and hydroxybenzoic acids inhibit the reaction in the direction of shikimate dehydrogenation (Balinsky and Davies, 1961b). The significance of the inhibition in controlling the activity of the pathway is unknown. 

Eklund, T. 1985. Inhibition of microbial growth at different pH levels by benzoic and propionic acids and esters of p-hydroxybenzoic acid. International Journal of Food Microbiology 2 159-167. 

Fig. 3.19 Effects of total phenoUc acid composed of a 4-equal-molar mixture of p-coumaric acid, ferulic acid,p-hydroxybenzoic add, and vanillic acid on absolute rates of leaf expansion (cm /day r = 0.44) of 12 day-old cucumber seedlings and microbial populations (CFU/g sod F = 0.49) that can utilize phenolic acids as a sole carbon source in Cedi A soil (a). Relationships between phenolic add-utilizing microbes (CPU, colony forming units) and percent inhibition of absolute rates of leaf expansion for cucumber seedlings are presented in (b). Values for (b) were calculated from (a). Figures based on regressions from Blum et al. (2000). Plenum Publishing Corporation, regressions used with permission of Springer Science and Business Media...

Knosel indicated that a mixture of p-hydroxybenzoic, vanillic, p-coumaric and ferulic acids, added to soils at the rate of 10 yg of each acid g" soil, had little effect on the microbial population. Hov/ever in liquid culture media, soil streptomycetes were inhibited by vanillic, p-coumaric and... 

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