Influence of fatty acids on some microorganisms

Abstract

The sntihacterial and antifungal effect of fatty acids has been recognized a long tinre ago (SALTON 1968, BYRDE 1969. Generally, fatty acids are t'osic to fungi, and the degree of toxicity depends upon the chain lengt'li, t'he coricentration of t'he acids, and the pH of t'he incubat'ion niediiim (HERTING and DRURP 1974, LIEDEBERG and 1,mr)E-BEKG 1974, SLYNSARENKO et nZ. 1974.I n this coniniiinication we deal with t'he effect of propionic acid on the growt'li arid the ac.ciiirinlation of keto compounds hy different microorganisms, naniely deiobactei uerop,tcx, *Srtcc?iaroiiiyce.s cereoi.siue, P e~i c i l b i u ?~ 'r2otatu,n/, P. chrysopnnni, P. c i t m u y -C P S , and P. oreliciim.Culture media : Aerobacter aeroyenes PRL-R, was grown in shaking rultiires a t 30 "C for 12 hrs on a synt,hetic medium prcvionsly-described by I<anIEL and A4NnERsoX (1966). 8ncchnrorqcrs cerecisine was maintained on SABOURAUD a'gar slant's. The gromt'li mediuin consisted of 104 gliieose, O.:iq/, (SH,),SO,, 0.1:; liH,PO,, O.OS(~~;, MgS0,. 7 H,O, 0.01% XaCI, 0.010; CaC'I,. 2 H,O. 0.2 pg biotin, 40 pg calcium pantothenate. 50 pg H,PO,, 4 pg CuSO, . 5 H,O. 10 pg KI, 20 pg PeC'I, . 6 H,O, 40 pg JIn80, . H,O. 20 pg Na,MoO, . 2 H20, and 40 pg ZnSO, . 7 H,O/100 1111 niediiim. The pH was adjusted to 5.0. Cells were grown in shaking cultures a t 30 "C for 36 hrs. Different Pen.iciZ/iuitL species n w e grow1 in surface cultures on CZAPEK Dox's media at, pH 5.0 and 30 "C for 8 days.Unless otherwise stated. propionate wa.s added at a conrentrabiori of 0.15$; to the above niedia. Growth was determined on t'he basis of dry weight.(:lucose was det.ermined by the arseno-molybdate method described by XELSON (1944). Total keto compounds were est'imated according t,o the method of FRIEDEMAN and HAUGEX (1943). Incliridual ket,o-acids were quantitatively determined by paper chromatography as t>lieir 2.4-dinitrophenyl hydrazine derivatives according t o the method of HARPER et al. (1962). Caprat>e and propionate were tit,rinietrically determined after steam distillation according to HORWITZ ct al.(1 970 j.Addition of propionate to A . aeiogenes cultnres affected growth and glucose disappearance to a limited extent (Fig. la). These results are in agreement with reported effects of long chain fatty acids on the other Gram-negative bacteria (GALBRB~TII et ctl. 1971, UALBRAITII and MILLER 1973). However, a n increase in the total keto coinpounds accnitinlation was ohserved (Fig. 1A).A 40% inhibition of growth and 13% increase in the accummilation of total keto conipounds without any change in glucose consulription was reported for the yeast S. ceieaisine in presence of 0.15 propionate (Fig. 1B).Propionate had a strong inhibitory effect on P. notaturn, P. chrysogenunz, and P. citioniyces in surface cultures. The growth inhibition ranged from about 86 to 929; and mas associated with a significant increase in total keto compounds. Under normal conditions and in absence of fatty acids, all Penicilliuni-species tested accuniulate small I ) Supported by a grant (KO. ...