Isolation of Clostridium absonum and Its Cultural and Biochemical Properties

Abstract

A new procedure for isolation of Clostridium absonum was devised. Sixtyseven strains of C. absonum were isolated from 135 soil samples, but no strain of C. absonum could be found from human fecal samples. The lecithinase, hemolysin, and lethal toxin in the culture filtrates of this species exhibited low avidity for C. perfringens type A antitoxin. The three activities were inseparable by the present method of purification. A reinvestigation of biochemical properties revealed that incomplete suppression of lecithinase reaction by C. perfringens type A antitoxin and no fermentation of raffinose, melibiose, and starch are useful criteria to differentiate C. absonum from C. perfringens, and that positive, although weak, gelatin liquefaction and fermentation of trehalose are useful to differentiate it from C. paraperfringens.

Epimerization of chenodeoxycholic acid to ursodeoxycholic acid by Clostridium baratii isolated from human feces

“…C. baratii belongs to the Clostridium 16S rDNA phylogenic cluster I, and is most closely related to C. absonum [33]. Interestingly, under our test conditions, the ability of the new C. baratii strains to epimerize CDCA to UDCA was as efficient as that of C. absonum, a soil isolate which could never be found in human feces [19,20,34]. Members of the Clostridium cluster I have been found in the predominant human microbiota using 16S rDNA sequence analysis [36,37], whereas in another study including nine healthy human volunteers, counts of the Clostridium histolyticum group (Clostridium clusters I and II) with the Chis150 probe, were estimated to be in the range of 1 · 10 7 to 7 · 10 8 organisms g À1 dry feces [38], i.e., 0.3 · 10 7 to 2.3 · 10 8 organisms g À1 wet feces.…”

“…Knowledge of bacteria which generate UDCA in the gut is clinically relevant, due to the multiple beneficial effects of this bile acid on human health. We chose 8H agar for the isolation procedure since clostridia were the only anaerobic 7-epimerizing bacteria known hitherto [19,20,27], and previous attempts to isolate epimerizing organisms from the intestinal microbiota of healthy individuals using other media have failed [19,20,34]. Using this medium, we were able to isolate for the first time five strains capable of epimerizing CDCA to UDCA, from the stool of a healthy volunteer.…”

Epimerization of chenodeoxycholic acid to ursodeoxycholic acid byClostridium baratiiisolated from human feces

“…C. baratii belongs to the Clostridium 16S rDNA phylogenic cluster I, and is most closely related to C. absonum [33]. Interestingly, under our test conditions, the ability of the new C. baratii strains to epimerize CDCA to UDCA was as efficient as that of C. absonum , a soil isolate which could never be found in human feces [19,20,34]. Members of the Clostridium cluster I have been found in the predominant human microbiota using 16S rDNA sequence analysis [36,37], whereas in another study including nine healthy human volunteers, counts of the Clostridium histolyticum group ( Clostridium clusters I and II) with the Chis150 probe, were estimated to be in the range of 1 × 10 7 to 7 × 10 8 organisms g −1 dry feces [38], i.e., 0.3 × 10 7 to 2.3 × 10 8 organisms g −1 wet feces.…”

“…Knowledge of bacteria which generate UDCA in the gut is clinically relevant, due to the multiple beneficial effects of this bile acid on human health. We chose 8H agar for the isolation procedure since clostridia were the only anaerobic 7‐epimerizing bacteria known hitherto [19,20,27], and previous attempts to isolate epimerizing organisms from the intestinal microbiota of healthy individuals using other media have failed [19,20,34]. Using this medium, we were able to isolate for the first time five strains capable of epimerizing CDCA to UDCA, from the stool of a healthy volunteer.…”

The Suitability of Tórtora's Medium for the Production of Enterotoxin in Clostridium perfringens Strains

“…The inoculated SCMM tubes were heated at 100 C for 60 min in a water bath, cooled, and incubated at 37 C until gas was produced (27). All the cultures producing gas were plated on 1 % glucose blood agar plates (13) and incubated anaerobically at 37 C in an 80% N2, 10% CO2, and 10% H2 atmosphere for 24 to 48 hr. One (or exceptionally two) colony suspected of being C. perfringen s was picked from each plate and transferred to CMM without starch.…”