The effect of hydrogen peroxide on spores of Clostridium bifermentans.

The effect of hydrogen peroxide on the germination, colony formation and structure of spores of Clostridium bifermentans was examined. Treatment with 0.35 M-hydrogen peroxide increased the germination rate at 25 degrees C but increasing the temperature or concentration of hydrogen peroxide decreased both the germination rate and colony formation. The presence of Cu2+ increased the lethal effect of hydrogen peroxide on colony formation as much as 3000-fold. Pre-incubation of spores with Cu2+ before treatment with hydrogen peroxide produced a similar increase, but this could be eliminated by washing the spores with dilute spores--apparently from the coat--and treatment with dithiothreitol, which also removes spore-coat protein, increased the lethal effect of hydrogen peroxide 500-fold, suggesting that spore-coat protein has a protective effect against hydrogen peroxide.     

Appendages of Clostridium bifermentans Spores

Four distinct spore appendage types were detected in an electron microscope survey of 12 strains of Clostridium bifermentans. A smooth tubular appendage and a feather-like appendage are described in detail. In addition, hirsute tubular appendages and small pin-like appendages are depicted. Spores of four strains apparently lack appendages.     

Purification and amino acid sequence of two small, acid-soluble proteins from Clostridium bifermentans spores

Clostridium bifermentans spores contain two major small, acid-soluble, proteins (SASP) termed SASP-alpha and beta. The amino acid sequences of SASP-alpha and beta are almost identical, and are very similar to those of alpha/beta-type SASP from spores of C. perfringens and various Bacillus species. However, the C. bifermentans proteins contain an extra five amino acids in the middle of their sequence. Surprisingly, no gamma-type SASP were found in C. bifermentans or C. perfringens spores, although these are the most prominent SASP in spores of Bacillus species.     

Appendage Development in Clostridium bifermentans

The appendages of Clostridium bifermentans UK-A 1003 spores were shown to originate from a substance located just exterior to the outer forespore membrane. The dense spore coat develops along the periphery of this material, and, as the appendages develop in the cytoplasm, the coalescing spore coat intervenes between the appendages and their origin. Freeze etching revealed that the appendages are in the form of distinct fibers in proximity to the mature spore body. These fibers form a network around the spore, seemingly encasing it and insuring that the appendages remain attached to the mature, free spore. The inner wall of each appendage tubule is lined with fibers whereas the outer surface is smooth. The developing exosporium contained several layers consisting of small (3 nm) globular subunits; the outer exosporial surface is composed of relatively unstructured material.     

Transformation of cholic acid by Clostridium bifermentans

Suspensions of washed, resting-stage cells of Clostridium bifermentans were incubated with cholic acid under a variety of conditions in an attempt to manipulate the competing 7α-dehydroxylation and 7α-dehydrogenation reactions. Important variables thus identified were then tested in batch fermentation. Sodium thioglycollate was observed to inhibit dehydrogenation and to delay dehydroxylation. Zinc ion inhibited both dehydrogenation and dehydroxylation. In the presence of EDTA, near quantitative 7α-dehydrogenation was achieved with no associated dehydroxylation. Finally, the presence of air in the fermenter headspace enhanced both transformations, possibly through an effect on the redox potential of the medium.     

Biochemical properties of a beta-xylosidase from Clostridium cellulolyticum.

A 43-kDa beta-xylosidase from Clostridium cellulolyticum was purified to homogeneity. The enzyme releases xylose from p-nitrophenylxylose and xylodextrins with a degree of polymerization ranging between 2 and 5. The N-terminal amino acid sequence of the enzyme showed homologies with three other bacterial beta-xylosidases. By proton nuclear magnetic resonance spectroscopy, the enzyme was found to act by inverting the beta-anomeric configuration.     

Biohydrogenation of linoleic acid by Clostridium sporogenes, Clostridium bifermentans, Clostridium sordellii and Bacteroides sp.

Abstract Several strains of Clostridium bifermentans, Clostridium sporogenes and Clostridium sordellit and one strain of Bacteroides sp. hydrogenate linoleic acid into transvaccenic acid in vitro following the same pathway. Linoleic acid (18:2; 9- cis , 12- cis ) was first isomerised into 9- cis , 11- trans -octadecadienoic acid, after which the 9- cis double bond was reduced. These species also hydrogenated linoleic acid into an octadecenoic acid in vivo when mono-associated with gnotobiotic rats. Several other species of Clostridium and Bacteroides did not hydrogenate linoleic acid.     

Hydrolysis of bile acid conjugates by Clostridium bifermentans

Summary Two strains of Clostridium bifermentans have been investigated for their ability to hydrolyse bile acid conjugates under conditions suited to further transformation of the free acids liberated. In batch fermentation at 0.5 g/l substrate concentration, growing cells effected the near-quantitative hydrolysis of glycodeoxycholate, taurodeoxycholate and taurocholate within 48 h; glycocholate was 88% hydrolysed. At substrate concentration greater than 1.0 g/l however, taurine conjugates were less well hydrolysed. Further transformation of the liberated cholic acid to deoxycholic acid and/or 7-ketodeoxycholic acid was achieved, but quantitative conversion was not observed.