Showing papers in "Antonie Van Leeuwenhoek International Journal of General and Molecular Microbiology in 1990"

Trehalose in yeast, stress protectant rather than reserve carbohydrate

Abstract: Trehalose and glycogen are generally regarded as the two main reserve carbohydrates in yeast. However, several lines of evidence suggest that trehalose does not primarily function as a reserve but as a highly efficient protecting agent to maintain structural integrity of the cytoplasm under environmental stress conditions.

Combined heterotrophic nitrification and aerobic denitrification in Thiosphaera pantotropha and other bacteria.

Abstract: Reports of the simultaneous use of oxygen and denitrification by different species of bacteria have become more common over the past few years. Research with some strains (e.g. Thiosphaera pantotropha) has indicated that there might be a link between this 'aerobic denitrification' and a form of nitrification which requires rather than generates energy and is therefore known as heterotrophic nitrification. This paper reviews recent research into heterotrophic nitrification and aerobic denitrification, and presents a preliminary model which, if verified, will provide at least a partial explanation for the simultaneous occurrence of nitrification and denitrification in some bacteria.

The OxyR regulon.

Abstract: Treatment of Salmonella typhimurium and Escherichia coli cells with low doses of hydrogen peroxide results in the induction of thirty proteins and resistance to killing by higher doses of hydrogen peroxide. The expression of nine of the hydrogen peroxide-inducible proteins, including catalase, glutathione reductase and a novel alkyl hydroperoxide reductase is controlled by the positive regulator oxyR. OxyR is homologous to the LysR-NodD family of bacterial regulatory proteins and binds to the promoters of oxyR-regulated genes. The oxidized but not reduced form of the OxyR protein activates transcription of oxyR-regulated genes in vitro suggesting that oxidation of the OxyR protein brings about a conformational change by which OxyR both senses and transduces an oxidative stress signal to RNA polymerase.

Formation and breakdown of glycine betaine and trimethylamine in hypersaline environments

Abstract: Glycine betaine is accumulated as a compatible solute in many photosynthetic and non-photosynthetic bacteria--the last being unable to synthesize the compound--and thus large pools of betaine can be expected to be present in hypersaline environments. A variety of aerobic and anaerobic microorganisms degrade betaine to among other products trimethylamine and methylamine, in a number of different pathways. Curiously, very few of these betaine breakdown processes have yet been identified in hypersaline environments. Trimethylamine can also be formed by bacterial reduction of trimethylamine N-oxide (also by extremely halophilic archaeobacteria). Degradation of trimethylamine in hypersaline environments by halophilic methanogenic bacteria is relatively well documented, and leads to the formation of methane, carbon dioxide and ammonia.

Chemotaxonomy of the genus Talaromyces.

Abstract: Species of the ascomycetous genus Talaromyces have been examined for profiles of secondary metabolites on TLC. The greatest number of specific metabolites were produced on oatmeal-, malt extract- and yeast-extract sucrose agars. Profiles of intracellular secondary metabolites produced on oatmeal agar were specific for each species and provided a means of simple differentiation of the taxa. Examination of the most important species using high performence liquid chromatography (HPLC) allowed to solve some taxonomic problems. Known mycotoxins are produced by T. stipitatus (duclauxin, talaromycins, botryodiploidin), T. stipitatus chemotype II (emodin), T. panasenkoi (spiculisporic acid), T. trachyspermus (spiculisporic acid), T. trac macrosporus (duclauxin) and T. wortmannii (rugulosin). Wortmannin is produced by an atypical strain of T. flavus but not T. wortmannii. Several other secondary metabolites were discovered for the first time in the following species: Glauconic acid is produced by T. panasenkoi, T. ohiensis and T. trachyspermus; vermiculine by T. ohiensis; duclauxin by T. flavus var. macrosporus and the mitorubrins by T. flavus and T. udagawae. The profiles of secondary metabolites support the established taxonomy of the species based on morphology, showing the genetic stability of profiles of secondary metabolites in Talaromyces. Two new taxa are proposed: T. macrosporus comb. nov. (stat. anam. Penicillium macrosporum stat. nov.), and Penicillium vonarxii, sp. nov. for the anamorph of T. luteus.

Relationship between intestinal microecology and the translocation of intestinal bacteria.

Abstract: It is now well known that endogenous bacteria can translocate from the intestinal tract and cause many of the complicating infections seen in severely ill, hospitalized patients. Of the hundreds of bacterial species in the intestinal tract, relatively few aerobic/facultative species appear to translocate with any frequency. Van der Waaij and colleagues (1971, 1972a, 1972b) originally proposed that, by a process termed ‘colonization resistance’, strictly anaerobic bacteria prevented the intestinal overgrowth and subsequent translocation of these potentially pathogenic aerobic/facultative bacteria. Selective antimicrobial decontamination, designed to maintain colonization resistance, has been effective in reducing the incidence of infectious morbidity in high risk patients. However, the mechanisms controlling bacterial translocation remain unclear, but appear to depend on host factors, as well as on factors inherent in the microbe itself. There is both clinical and experimental evidence supporting the concept that strictly anaerobic bacteria do not readily translocate. Bacteria that are able to survive within macrophages (e.g., Salmonella species and Listeria monocytogenes) translocate easier than others, and there is recent experimental evidence that normal intestinal bacteria may translocate to the draining mesenteric lymph node within host phagocytes. There is also evidence that anaerobic bacteria translocate along with facultative species in situations associated with intestinal epithelial damage, i.e., burn trauma, oral ricinoleic acid, and acute mesenteric ischemia. In contrast, recent experimental evidence demonstrates that facultative bacteria can translocate across a histologically intact intestinal epithelium, and that the ileal absorptive cell may be at least one portal of entry prior to transport into deeper tissues. It is anticipated that further clarification of the routes and mechanisms involved in bacterial translocation will provide new insights into the treatment and prevention of a significant proportion of the infectious morbidity seen in severely ill, hospitalized patients.

Characterization of arsenopyrite oxidizing Thiobacillus. Tolerance to arsenite, arsenate, ferrous and ferric iron.

Abstract: Two strains of Thiobacillus, T. ferrooxidans and T. thiooxidans, have been isolated from a bacterial inoculum cultivated during a one-year period in a 1001 continuous laboratory pilot for treatment of an arsenopyrite/pyrite concentrate. The optimum pH for the growth of both strains has been found to be between 1.7 and 2.5. Because of the high metal toxicity in bioleach pulps, the tolerance of T. ferrooxidans and T. thiooxidans with respect to iron and arsenic has been studied. The growth of both strains is inhibited with 10 g/l of ferric ion, 5 g/l of arsenite and 40 g/l of arsenate. 20 g/l of ferrous iron is toxic to T. ferrooxidans but 30 g/l is necessary to impede the growth of T. thiooxidans.

Influence of light on growth and pigmentation of the yeast Phaffia rhodozyma

Abstract: Light and antimycin markedly affected growth and carotenoid synthesis by Phaffia rhodozyma. Exposure of the yeast to high light intensities on agar plates resulted in growth inhibition and decreased carotenoid synthesis. The carotenoid compositions of the yeast were also notably changed by light. Beta-zeacarotene increased, whereas beta-carotene and xanthophylls decreased including astaxanthin, phoenicoxanthin, and 3-hydroxy-3',4'-didehydro-beta,psi-caroten-4-one (HDCO). In liquid medium, growth of the wild-type strain (UCD-FST-67-385) was inhibited by antimycin, but this inhibition was relieved by exposure to light. Light also stimulated carotenoid synthesis about twofold in these antimycin-treated cells. Light may have rescued growth by induction of an alternative oxidase system which facilitated electron disposal when the main respiratory chain was inhibited by antimycin. Isolation and characterization of the oxidase enzymes should be useful in strain development for increased carotenoid production.

Arxula gen. nov. (Candidaceae), a new anamorphic, arthroconidial yeast genus.

Abstract: The new genus Arxula is proposed for the classification of xerotolerant, ascomycetous, anamorphic, arthroconidial yeasts. The genus is considered to be of endomycetaceous affinity.

Elemental metals as electron sources for biological methane formation from CO2.

Abstract: Several elemental metals were examined as potential electron donors for methanogenic bacteria, using both a single tube system where the metal was in direct contact with the cells, and a two-flask system, where metal and cells were not in direct contact, but had contact via the gas phase. With all organisms examined in the direct contact system, Feo, Alo and Zno served as electron donors for methanogenesis; some organisms used Nio or Sno as low-level electron donors. Of the metals tested, methanogenesis from H2+CO2 was inhibited by direct contact with Zno or Cuo, but not by Feo or Alo. Nio and Coo were inhibitory to some methanogens, with Nio being particularly inhibitory to the thermophilic strains tested. With all organisms examined in the two-flask system, Feo and Zno served as good electron sources for both methanogenesis and growth; Coo generated a very low level of methane and Cuo did not work at all. In either system Vo, Tio or Cdo did not serve as electron donors. The results suggest that some elemental metals (notably Feo, Alo and Zno) produce gaseous H2 by cathodic depolarization which is then consumed by the methanogen, thus accelerating oxidation of the metal by its metabolic activity. All of these reactions are thermodynamically favorable; however, some other metals that are clearly favorable for such a reaction on thermodynamic grounds (Tio and Vo) are very stable and do not serve as electron donors.

Utilization of mucin by oral Streptococcus species.

Abstract: The ability of oral Streptococcus strains to utilize oligosaccharide chains in mucin as a source of carbohydrate was studied in batch cultures. Pig gastric mucin, as a substitute of human salivary mucin, was added to chemically defined medium containing no other carbohydrates. Strains of S. mitior attained the highest cell density, while mutans streptococci: S. mutans, S. sobrinus, S. rattus, grew very little in the medium with mucin. S. mitis, S. sanguis, and S. milleri in decreasing order, showed intermediate growth. Mucin break-down as measured by sugar analyses indicated that oligosaccharide chains were only partially degraded. Every strain produced one or more exoglycosidases potentially involved in hydrolysis of oligosaccharide. The enzyme activities occurred mainly associated with the cells, and very little activity was found in the culture fluids. The relationships between glycosidase activities and growth, or mucin degradation were not always clear.

Candida shehatae--genetic diversity and phylogenetic relationships with other xylose-fermenting yeasts

Abstract: The xylose-fermenting yeasts Candida shehatae and Pichia stipitis were compared from extent of nuclear DNA complementarity and ribosomal RNA sequence similarity. Low levels of DNA relatedness confirmed that the two taxa are distinct biological species, but the similarity of rRNA sequences suggests that they only recently diverged. C. shehatae is comprised of three genetically divergent (ca. 50% DNA relatedness) subgroups that were accorded varietal status: C. shehatae var. shehatae, var. lignosa and var. insectosa. Estimates of phylogenetic distance from rRNA sequence similarity show C. shehatae and P. stipitis to be more closely related to Pachysolen tannophilus than to Saccharomyces cerevisiae, and that all of these budding yeasts are well separated from Schizosaccharomyces pombe.

Effects of sulfate on lactate and C2-, C3- volatile fatty acid anaerobic degradation by a mixed microbial culture.

Abstract: The effects of sulfate on the anaerobic degradation of lactate, propionate, and acetate by a mixed bacterial culture from an anaerobic fermenter fed with wine distillery waste water were investigated. Without sulfate and with both sulfate and molybdate, lactate was rapidly consumed, and propionate and acetate were produced; whereas with sulfate alone, only acetate accumulated. Propionate oxidation was strongly accelerated by the presence of sulfate, but sulfate had no effect on acetate consumption even when methanogenesis was inhibited by chloroform. The methane production was not affected by the presence of sulfate. Counts of lactate- and propionate-oxidizing sulfate-reducing bacteria in the mixed culture gave 4.5×108 and 1.5×106 viable cells per ml, respectively. The number of lactate-oxidizing fermentative bacteria was 2.2×107 viable cells per ml, showing that sulfate-reducing bacteria outcompete fermentative bacteria for lactate in the ecosystem studied. The number of acetoclastic methanogens was 3.5×108 viable cells per ml, but only 2.5×104 sulfate reducers were counted on acetate, showing that acetotrophic methanogens completely predominated over acetate-oxidizing sulfate-reducing bacteria. The contribution of acetate as electron donor for sulfate reduction in the ecosystem studied was found to be minor.

Re-examination of cellular cyclic β-1,2-glucans of Rhizobiaceae: Distribution of ring sizes and degrees of glycerol-1-phosphate substitution

Abstract: Gel-filtration and thin layer chromatography of low molecular weight carbohydrates from culture filtrates of Agrobacterium radiobacter, Isolate II, have shown, that next to the neutral beta-1,2-glucan fraction a major acidic fraction was present which was found to be glycerophosphorylated cyclic beta-1,2-glucans. Re-examination of cyclic beta-1,2-glucan preparations which had been obtained by extraction of Rhizobium cells with hot phenol-water also showed these acidic modified beta-1,2-glucans to be present. Cyclic beta-1,2-glucans from R. leguminosarum (9 strains) and of R. phaseoli (1 strain) had ring size distribution with degrees of polymerisation (DPs) of 19 and 20 as major ring sizes of which a minor part was glycerophosphorylated; beta-1,2-glucans of R. trifolii (3 strains) had ring sizes with DPs measuring 19-22 as prominent components which were largely unsubstituted, and R. meliloti (7 strains) had beta-1,2-glucans with ring size distributions extending to still higher DPs of 19-25 of which the major part appeared to be glycerophosphorylated.

Kinetic studies of phenol degradation by Rhodococcus sp. P1. I. Batch cultivation.

Abstract: Rhodococcus sp. P1 utilizes phenol as the sole carbon and energy source via the β-ketoadipate pathway. In batch cultivation, concentrations up to 2.8g · l-1 phenol were degraded. The highest values for the specific growth rate of 0.32 h-1 were obtained at concentrations near 0.25 g · l-1. At higher concentrations, substrate inhibition was observed, characterized by increases in lag phase and decreasing growth rates. A mathematical expression was proposed to fit the kinetic pattern of phenol inhibition on the specific growth rate μ: $$\begin{gathered} \mu = \mu _{\max } \frac{S}{{S + K_S }}{\text{ }}\exp {\text{ }}( - (\frac{S}{{K_1 }})^K ) \hfill \\ with{\text{ }}\mu _{\max } = 0.33h^{ - 1} ,{\text{ }}K_S = 0.00032g \cdot 1^{ - 1} ,{\text{ K = 1}}{\text{.44}}{\text{.}} \hfill \\ \end{gathered} $$

Growth stimulation of Treponema denticola by periodontal microorganisms.

Abstract: Previous experiments have indicated that enrichment of subgingival plaque in human serum can lead to the accumulation of Treponema denticola. T. denticola depends on bacterial interactions for its growth in serum. Aim of the present study was to identify specific microorganisms involved in the growth stimulation of T. denticola. To this end, strains isolated from previous plaque enrichment cultures were tested for growth stimulation in co-cultures with T. denticola. In addition, growth of T. denticola was tested in culture filtrates of the same strains, Bacteroides intermedius, Eubacterium nodatum, Veillonella parvula and Fusobacterium nucleatum were found to enhance growth of T. denticola in co-cultures. A continuous co-culture of T. denticola, F. nucleatum and B. intermedius in human serum gave very high levels of T. denticola, up to 3.109 ml-1. Mechanisms involved in growth stimulation may include the ability of B. intermedius and E. nodatum to cleave the protein-core of serum (glyco-)proteins, making these molecules accessible for degradation by T. denticola. In addition, E. nodatum was found to produce a low-molecular weight growth-factor for T. denticola, that was heat-stable and acid as well as alkaline resistant. V. parvula may provide peptidase activities complementary to those of T. denticola. The nature of the growth enhancing activity of F. nucleatum is yet unknown. The data support the dependency of T. denticola on other bacterial species for growth in the periodontal pocket.

Viability of Salmonella spp and indicator microorganisms in seawater using membrane diffusion chambers.

Abstract: Diffusion chambers with polycarbonate membrane-filter side walls were used to study the comparative survival of fecal indicators (Escherichia coli and Streptococcus faecalis) and enteric pathogens (Salmonella enteritidis, S. postdam, S. typhimurium, S. london and S. infantis) in natural seawater. It was observed that the percentages of sublethal injury increased with exposure to the marine environment, and that these environmental injuries depended on the microorganism considered. A large proportion of cells lost their ability to produce colonies on the selective media, but retained this capability on a nonselective medium. All microorganisms showed low survival percentages (less than 11%) after 48 hrs of exposure to seawater, but there is not a high difference among the microbial species studied. The results obtained in the present study showed that there were no differences in the survival rates between the serotypes of Salmonella tested. Moreover, Salmonella spp exhibited a similar persistence to E. coli in the marine environment.

A review of the role of 70 kDa heat shock proteins in protein translocation across membranes.

Abstract: The compartmentalization of essential hsp70 proteins indicates that hsp70s carry out crucial functions in several compartments of the cell. The use of conditional mutants has allowed study of the cellular processes that require hsp70 function. For efficient translocation of proteins across membranes hsp70s are required in the cytoplasm, as well as in the matrix of mitochondria and in the lumen of the endoplasmic reticulum.

Basic features of the staphylococcal heat shock response.

Abstract: The major heat shock proteins of Staphylococcus aureus had apparent Mrs of 84,000, 76,000, and 60,000, and other prominent proteins of Mrs 66,000, 51,000, 43,000 and 24,000 were also induced. Staphylococcus epidermidis showed a similar response. These proteins were also induced by CdCl2, ethanol and apparently osmotic stress (1.71 M NaCl or 2.25 M sucrose). Most of the proteins sedimented with the membrane fraction, but the Mr 60,000 protein remained in the cytoplasm.

Characterization of two sulfate-reducing bacteria from the gut of the soil-feeding termite, Cubitermes speciosus

Abstract: Two sulfate-reducing bacteria (SRB) were isolated from a mixed culture enriched with benzoate obtained from gut homogenate of the soil-feeding higher termite, Cubitermes speciosus. The organisms were vibrioid rods, staining Gram-negative, which performed incomplete substrate oxidation. They differed in several features. The smaller one, strain STp, was motile with a single polar flagellum. This strain differed from Desulfovibrio desulfuricans only by its inability to oxidize malate and pentanol. The bigger one, strain STg, differed from Desulfovibrio giganteus only by its nonmotility and a lower length. It is the first evidence of the presence of SRB in termite gut.

Modes of lactose uptake in the yeast species Kluyveromyces marxianus.

Abstract: Twelve lactose-assimilating strains of the yeast species Kluyveromyces marxianus and its varieties marxianus, lactis and bulgaricus were studied with respect to transport mechanisms for lactose, glucose and galactose, fermentation of these sugars and the occurrence of extracellular lactose hydrolysis. The strains fell into three groups. Group I (two strains): Fermentation of lactose, glucose and galactose, extracellular lactose hydrolysis, apparent facilitated diffusion of glucose and galactose; Group II (two strains): Lactose not fermented, glucose and galactose fermented and transported by an apparent proton symport, extracellular hydrolysis of lactose present (one strain) or questionable; Group III (eight strains): Lactose, glucose and galactose fermented, lactose transported by an apparent proton symport mechanism, extracellular hydrolysis of lactose and transport modes for glucose and galactose variable.

Influence of the blood group reactive substances in saliva on the aggregation of Streptococcus rattus

Abstract: The interaction of blood group reactive substances in saliva with bacteria was investigated by testing saliva from persons with different blood groups in a bacterial aggregation assay with Streptococcus rattus HG 59, originally S. rattus BHT. For blood group A, saliva from 10 persons out of 11 aggregated S. rattus and for blood group O, saliva from 10 persons out of 16 aggregated S. rattus. For blood group B, saliva from 6 persons out of 8 aggregated S. rattus weakly and the average aggregation activity of blood group B was much lower than for blood group A or O. In addition, saliva from 3 non-secretors did not aggregate S. rattus. The role of blood group antigens in bacterial aggregation was confirmed by inhibition studies with blood group specific sugars and various other sugars. GalNAc, specific for blood group A, inhibited bacterial aggregation by saliva whereas D-galactose, specific for blood group B, and D-fucose, specific for blood group O, did not. In addition, sialic acid, a major terminal sugar residue in mucins, also inhibited the bacterial aggregation. This study shows that the blood group and secretor status of a person may influence the interaction of saliva with bacteria in the oral cavity.

Kinetic studies of phenol degradation by Rhodococcus sp. P1. II. Continuous cultivation.

Abstract: The degradation of phenol by Rhodococcus sp. P1 was studied in continuous culture systems. The organism could be adapted by slowly increasing concentration, step by step, up to 30.0 g.l-1 phenol in the influent. The degradation rate reached values of about 0.3 g.g dry mass-1.h-1. Large step increases in phenol concentration and addition of further substrates (e.g., catechol) were tolerated up to a certain concentration. With increasing dilution rate and increasing inlet phenol concentration the stability of the system decreased. Nomenclature: D--Dilution rate, h-1, Dc--Critical dilution rate, h-1, Dx--Yield, g dry mass.l-1.h-1, Ks--Monod saturation constant, g.l-1, S--Growth-limiting substrate concentration in culture broth, g.l-1, SR--Growth-limiting substrate concentration in feed, g.l-1, mean--Biomass concentration in culture broth, g.l-1, YS--Yield constant, g cell dry mass.g substrate-1, mu--Specific growth rate, h-1, mu max--Maximum growth rate, h-1.

Phylogenetic relationships among species of the genus Issatchenkia Kudriavzev.

Abstract: The phylogenetic relatedness of Issatchenkia spp. was estimated from partial rRNA sequences in two regions of the large subunit and one region of the small subunit. I. terricola was the most divergent species of the genus, differing from other members by 18% nucleotide differences in the highly variable 25S-635 region. These data indicate Issatchenkia to be the most divergent ascomycetous yeast genus presently known.

Behaviour of Aspergillus flavus in presence of Aspergillus niger during biosynthesis of aflatoxin B1.

Abstract: Aspergillus niger or Aspergillus tamarii when grown as mixed cultures with toxigenic A. flavus inhibits biosynthesis of aflatoxin by A. flavus, owing primarily to its ability to produce inhibitors of aflatoxin biosynthesis and to their ability to degrade aflatoxin. Gluconic acid partly prevents aflatoxin production. The other factors such as changes in pH of the medium and the effect on the growth of A. flavus have no role in imparting capabilities to these cultures to inhibit aflatoxin production by A. flavus.

Identification of mutans streptococci with monoclonal antibodies.

Abstract: Mutans streptococci have been correlated with dental caries. The identification of the species within this group is still a problem. The characterization of a monoclonal antibody (Mab) OMVU10 against S. sobrinus as well as the isolation and characterization of Mabs against S. mutans (OMVU30 and OMVU31), S. cricetus (OMVU40) and mutans streptococci (OMVU2) is described. The epitope specificity for OMVU10 and OMVU31 was cell-wall antigen B in both cases although both Mabs recognized different species-specific epitopes. OMVU40 was cross reactive with Streptococcus sanguis taxon 3. All other Mabs were specific for one species. Using these Mabs, a key to the identification of mutans streptococci is developed. This key was tested for 85 wild type isolates of mutans streptococci and proved to be highly reliable and easy to perform.

Kurtzmanomyces tardus sp. nov., a new anamorphic yeast species of basidiomycetous affinity.

Abstract: A new yeast species of basidiomycetous affinity Kurtzmanomyces tardus was isolated from contaminated demineralized water. It differs from K. nectairii, the only other Kurtzmanomyces species so far described, in its carbon assimilation pattern and low DNA-DNA homology (2.3% +/- 2.1).

Adaptation of Escherichia coli to elevated temperatures: the metA gene product is a heat shock protein

Abstract: When t h e s h i f t i s t o a h i g h e r t e m p e r a t u r e t h e a d a p t a t i o n o f mesophilic bacteria such as Escherichia coli involves at least two distinct control mechanisms. One mechanism is the \"heat shock response\", a stress response in which a large number of genes about 17 \"heat shock\" genes with sigma-32 promoters are transcribed (for review see Neidhardt and VanBogelen, 1987). The other mechanism is the control of growth rate by the availability of endogenous methionine, that is limited due to the extreme temperature sensitivity of the first enzyme in the pathway homoserine transsuccinylase (HTS). Recent studies, presented in this communication, indicate t h a t these two control mechanisms a r e l i n k e d , a s NTS i s a l s o a h e a t s h o c k p r o t e i n . When cultures of wild type strains of E. coil, growing exponentially at 37~ in minimal (salt-glucose) medium, are shifted to higher temperatures (up to 44~ the growth rate immediately assumes a new, lower value, c h a r a c t e r i s t i c o f t h a t t e m p e r a t u r e ( F i g 1 ) .

Anaerobic degradation of 1,3-propanediol by sulfate-reducing and by fermenting bacteria.

Abstract: Three strains of strictly anaerobic Gram-negative, non-sporeforming, motile bacteria were enriched and isolated from freshwater sediments with 1,3-propanediol as sole energy and carbon source. Strain OttPdl was a sulfate-reducing bacterium which grew also with lactate, ethanol, propanol, butanol, 1,4-butanediol, formate or hydrogen plus CO2, the latter only in the presence of acetate. In the absence of sulfate, most of these substrates were fermented to the respective fatty acids in syntrophic cooperation with Methanospirillum hungatei. Sulfur, thiosulfate, or sulfite were reduced, nitrate not. The other two isolates degraded propanediol only in coculture with Methanospirillum hungatei. Strain OttGlycl grew in pure culture with acetoin and with glycerol in the presence of acetate. Strain WoAcl grew in pure culture only with acetoin. Both strains did not grow with other substrates, and did not reduce nitrate, sulfate, sulfur, thiosulfate or sulfite. The isolates were affiliated with the genera Desulfovibrio and Pelobacter. The pathways of propanediol degradation and the ecological importance of this process are discussed.