細菌芽胞の発芽におよぼすソルビン酸とアラボン酸の影響

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It is sometimes preferable to keep food products in a lower range of pH in order to in-crease antibacterial action of certain food preservatives, since the effectiveness of most chemi-cals to microorganisms can be enhanced much more in acidic than non-acidic medium. According to BELL et al.13) and OKA12) the growth inhibitory action of sorbic acid depends much upon the concentration of undissociated molecules. The higher in the concentration of undissociated molecules the more active in the inhibitory effect. OKADA1) recently proposed the use of arabono-gamma-lactone as a safe pH-adjusting agent to the fish jelly products such as fish sausage to prolong the shelf life of the products, without any appreciable effect on its resiliency even after heat processing. His method is based on the fact that arabonic acid, a heat degradation product from arabono-gamma-lactone, will be able to provide the product with acidic condition which may serve a longer shelf life. The present report deals with the effect of sorbic acid on the germination and outgrowth of the spores of Bacillus subtilis MARBURG strain in the medium, pH of which has been adjusted with arabonic acid. As seen in Fig. 1, arabonic acid alone was not effective, even at pH value of 5.0, to prevent the spores from germination that was estimated by the reading of optical density of nutrient broth, to which inoculum of methylen blue stainable spores appeared in the broth would indicate a high synchrony of the germination. And, a subsequent increase in the optical density after this period can be interpreted the convertion of outgrown spores to vegetative cells. To the contrary, the presence of 0.1% of sorbic acid in the same medium with pH 5.5 was enough to suppress the outgrowth of the spores after being incubated for 5 hours, though the rate of germination was almost the same degree as observed in the experiment mentioned above (Fig. 2). In addition, there observed a retard in the reduction of optical density in the liqueid medium at pH 5.0 during 5 hours of incubation and the proportion in number of unstainable spores to total spores was kept nearly constant in the same incubation period, resulting no spore germination. Since the mixture of NFS (nitrofurazone) and NFA (2-nitro-2-furylacrylamide) showed no remarkable effect on both germination and outgrowth of the spores, the nature of inhibition on bacteria by these nitrofuran derivatives might differ from that of sorbic acid. As seen in Figs. 2 and 4, sorbic acid at pH 7.0 was no more inhibitive for germination and outgrowth of the spores.

細菌芽胞の発芽におよぼすソルビン酸とアラボン酸の影響

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