Screening of Lactic Acid Bacteria Having the Ability to Produce Reuterin

Abstract

Lactic acid bacteria (LAB) which produce reuterin, a low molecular weight antimicrobial substance, were screened by incubating LAB cells with glycerol in an anaerorobical system. Among the 148 strains of LAB tested, Lactobacillus coryniformis 394 displayed the highest ability to produce reuterin. This strain produced a mixture of reuterin and the corresponding hydrate form which were identified by H-NMR and C-NMR spectrum analyses. Highest amount of reuterin was produced in a glycerol solution containing 0.5% CaCO3 at 25•Ž under anaerobic conditions. Reuterin from L. coryniformis 394 strongly inhibited the growth of fungi, yeast and various strains of bacteria but showed no inhibitory effect on LAB.

Production of 3-Hydroxypropionaldehyde in Silage Inoculated withLactobacillus coryniformisPlus Glycerol

“…These strains were Lb. coryniformis 394, 6) which produces 3-HPA, and Lactobacillus rhamnosus NGRI 0110, 3) which shows no 3-HPA productivity. The LAB inoculants were prepared by individually culturing the strains in MRS broth (Difco, Detroit, MI, USA) at 37 C for 24 h. An aliquot of the broth, based on enumeration of the bacterial cells with a hemacytometer, was transferred to the water to wet the rice straw.…”

“…The NaOHtreated extract was then used as a blank with the addition of the abovedescribed coloring reagents and subsequent incubation at 40 C for 1 h. As standard for 3-HPA, the supernatant obtained by centrifugation of Lb. coryniformis 394 culture in the glycerol solution, which we described previously, 6) was used. The amount of 3-HPA in the supernatant was determined by two methods, the original colorimetric method 10) and HPLC.…”

“…HPLC estimated the amount of 3-HPA based on a peak area of a known molar amount of glycerol. 6) Tests of the modifications of the colorimetric treatment. Prior to the determination of HLC in the silage, we performed three tests to determine the influence of our modifications of the colorimetric treatment.…”

“…In a previous study, 6) we found that a strain of homofermentative LAB (Lactobacillus coryniformis 394) fermented glycerol efficiently to 3-hydroxypropionaldehyde (3-HPA), which is known as an antimicrobial component, reuterin. 7,8) Furthermore, we observed that inoculation with Lb.…”

“…Although 3-HPA in some liquid bacterial cultures has been detected using certain chromatographic and colorimetric methods, [6][7][8]10) detection of 3-HPA in more complex natural matrices in which 3-HPA is supposed to be produced by certain bacteria, e.g., human and animal feces and silage, has not been reported. In the attempt to detect 3-HPA in these complex matrices by the chromatographic or colorimetric methods, some other component tends to be confused with 3-HPA, and this makes it difficult to determine whether the complex matrices contain 3-HPA.…”