RT Journal Article SR Electronic(1) A1 Lyon, G. D.YR 1978 T1 Attenuation by Divalent Cations of the Effect of the Phytoalexin Rishitin on Erwinia carotovora var. atroseptica JF Microbiology, VO 109 IS 1 SP 5 OP 10 DO https://doi.org/10.1099/00221287-109-1-5 PB Microbiology Society, SN 1465-2080, AB Rishitin at 300 μg ml–1 rapidly decreased oxygen uptake by Erwinia carotovora var. atroseptica suspended in 0·1% (w/v) peptone water. Variation in the composition of the suspending medium affected sensitivity to rishitin, with Mg2+ and, to a lesser extent, Ca2+ decreasing bacterial sensitivity. Addition of 100 μg rishitin ml–1 affected cell membrane permeability causing an increase in conductivity of the suspending medium. Inhibition of oxygen uptake by the cationic surfactant hyamine 2389 or by sodium lauryl sulphate was also alleviated by the addition of Mg2+ suggesting that rishitin may act directly on cell membranes of bacteria, possibly in a manner similar to a cationic surfactant or a membrane-active antibiotic. The results also suggest that the sensitivity of E. atroseptica to rishitin in potato tubers may be affected by variation in their Mg2+ or Ca2+ content. Phaseollin did not inhibit respiration of E. atroseptica., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-109-1-5