Clostridium hungatei sp. nov., a mesophilic, N2-fixing cellulolytic bacterium isolated from soil.

Two strains of obligately anaerobic, mesophilic, cellulolytic, N2-fixing, spore-forming bacteria were isolated from soil samples collected at two different locations near Amherst, MA, USA. Single cells of both strains were slightly curved rods that measured between 2 and 6 microm in length and approximately 0.5 microm in diameter.

A methyl-accepting protein involved in multiple-sugar chemotaxis by Cellulomonas gelida.

Tethered-cell and capillary assays indicated that L-methionine is required by Cellulomonas gelida for its normal cell motility pattern and chemotaxis and that S-adenosylmethionine is involved in sugar chemotaxis by this cellulolytic bacterium. In addition, in vivo methylation assays showed that several proteins were methylated in the absence of protein synthesis. The incorporated methyl groups were alkali sensitive.

Ultrastructural diversity of the cellulase complexes of Clostridium papyrosolvens C7.

Transmission electron microscopy was used to investigate the ultrastructural features of diverse cellulase and cellulase-xylanase multiprotein complexes that are components of the cellulase-xylanase system of Clostridium papyrosolvens C7. The multiprotein complexes were separated by anion-exchange chromatography into seven biochemically distinguishable fractions (F1 to F7). Most individual F fractions contained, in relatively large numbers, an ultrastructurally recognizable type of particle that occurred only in smaller numbers, or not at all, in the other F fractions.

Multicomplex cellulase-xylanase system of Clostridium papyrosolvens C7.

The cellulase system of Clostridium papyrosolvens C7 was fractionated by means of ion-exchange chromatography into at least seven high-molecular-weight multiprotein complexes, each with different enzymatic and structural properties. The molecular weights of the complexes, as determined by gel filtration chromatography, ranged from 500,000 to 660,000, and the isoelectric points ranged from 4.40 to 4.

Cellobiose chemotaxis by the cellulolytic bacterium Cellulomonas gelida.

In the course of a study on the bacterial degradation of plant cell wall polysaccharides, we observed that growing cells of motile cellulolytic bacteria accumulated, without attachment, near cellulose fibers present in the cultures. Because it seemed likely that the accumulation was due to chemotactic behavior, we investigated the chemotactic responses of one of the above-mentioned bacteria (Cellulomonas gelida ATCC 488). We studied primarily the responses toward cellobiose, which is the major product of cellulose hydrolysis by microorganisms, and toward hemicellulose hydrolysis products.

Characterization of the extracellular cellulase from a mesophilic clostridium (strain C7).

An extracellular, 700,000-Mr multiprotein complex that catalyzed the hydrolysis of crystalline cellulose (Avicel) was isolated from cultures of Clostridium sp. strain C7, a mesophile from freshwater sediment. In addition to cellulose (Avicel, ball-milled filter paper), the multiprotein complex hydrolyzed carboxymethylcellulose, cellodextrins, xylan, and xylooligosaccharides.

Cellulase system of a free-living, mesophilic clostridium (strain C7).

The enzymatic activity responsible for crystalline cellulose degradation (Avicelase activity) by a mesophilic clostridium (strain C7) was present in culture supernatant fluid but was not detected in significant amounts in association with whole cells or in disrupted cells. Cells of the mesophilic clostridium lacked cellulosome clusters on their surface and did not adhere to cellulose fibers. The extracellular cellulase system of the mesophilic clostridium was fractionated by Sephracryl S-300 gel filtration, and the fractions were assayed for Avicelase and carboxymethylcellulase activities.

Clostridium methylpentosum sp. nov.: a ring-shaped intestinal bacterium that ferments only methylpentoses and pentoses.

An intestinal bacterium isolated from a human subject utilized only two methylpentoses (L-rhamnose and L-fucose) and two pentoses (L-lyxose and D-arabinose) as fermentable substrates, among many compounds tested. The isolate was obligately anaerobic and had a distinctive morphology, its cells being rods bent in the shape of rings with the ends slightly overlapping. Single ring-shaped cells and left-handed helical chains of cells were present in cultures.

Nitrogen fixation by anaerobic cellulolytic bacteria.

Four strains of anaerobic nitrogen-fixing, cellulose-fermenting bacteria were isolated in pure culture from freshwater mud and soil. Nitrogenase activity was demonstrated in these strains and also in several previously described anaerobic cellulolytic bacteria isolated from various natural environments. These are the first anaerobic bacteria known to use cellulose as an energy source for nitrogen fixation.

Bacteroides pectinophilus sp. nov. and Bacteroides galacturonicus sp. nov.: two pectinolytic bacteria from the human intestinal tract.

Studies on the physiological characteristics of two obligately anaerobic, rod-shaped bacteria from the human intestinal tract indicated that the organisms represented two previously undescribed species of Bacteroides, for which we propose the names Bacteroides pectinophilus (type strain, N3) and Bacteroides galacturonicus (type strain, N6). Both strains were pectinophilic; that is, they utilized as fermentable substrates for growth only pectin and a few related compounds. The two species differed significantly from each other in guanine plus cytosine content of the DNA, in substrate utilization patterns, and in other phenotypic characteristics.

Anaerobic cellulolytic bacteria from wetwood of living trees.

Obligately anaerobic, mesophilic, cellulolytic bacteria were isolated from the wetwood of elm and maple trees. The isolation of these bacteria involved inoculation of selective enrichment cultures with increment cores taken from trees showing evidence of wetwood. Cellulolytic bacteria were present in the cores from seven of nine trees sampled, as indicated by the disappearance of cellulose from enrichment cultures.

Treponema saccharophilum sp. nov., a large pectinolytic spirochete from the bovine rumen.

A large, obligately anaerobic spirochete (strain PB) was isolated from bovine rumen fluid by a procedure involving rifampin as a selective agent. The helical cells measured 0.6 to 0.

Nutritionally limited pectinolytic bacteria from the human intestine.

A selective procedure was used to isolate pectinolytic intestinal bacteria from human subjects. The three isolates with the greatest pectinolytic activity utilized pectin and a few related compounds as fermentable substrates for growth but did not utilize any other compound tested. Thus, their substrate utilization pattern was markedly different from that of previously described intestinal pectinolytic isolates.

Enhancement of chemotaxis in Spirochaeta aurantia grown under conditions of nutrient limitation.

Spirochaeta aurantia M1 cells were grown in a chemostat under conditions of energy and carbon source limitation. The chemotactic responses of the chemostat-grown cells were compared with those of S. aurantia cells grown in batch culture in the presence of excess energy and carbon source.

Pectinolytic enzymes of oral spirochetes from humans.

Five strains of obligately anaerobic, pectin-fermenting spirochetes were isolated from the subgingival plaque of humans. The strains produced two extracellular enzymatic activities that functioned in pectin degradation. One of these enzymatic activities was pectin methylesterase (EC 3.

Mesophilic cellulolytic clostridia from freshwater environments.

Eight strains of obligately anaerobic, mesophilic, cellulolytic bacteria were isolated from mud of freshwater environments. The isolates (C strains) were rod-shaped, gram negative, and formed terminal spherical to oval spores that swelled the sporangium. The guanine plus cytosine content of the DNA of the C strains ranged from 30.

Enzymatic activities for interconversion of purines in spirochetes.

Enzymatic activities that catalyze the interconversion of purines and purine derivatives were detected in cell extracts of Spirochaeta aurantia, Spirochaeta stenostrepta, Treponema succinifaciens, and Treponema denticola. Phosphoribosyltransferase activities present in cell extracts of each of the four spirochete species functioned in the conversion of adenine, hypoxanthine, and guanine to AMP, IMP, and GMP, respectively. Nucleotidase activities in the extracts mediated the formation of nucleosides from nucleotides.

Properties of acetate kinase isozymes and a branched-chain fatty acid kinase from a spirochete.

Spirochete MA-2, which is anaerobic, ferments glucose, forming acetate as a major product. The spirochete also ferments (but does not utilize as growth substrates) small amounts of l-leucine, l-isoleucine, and l-valine, forming the branched-chain fatty acids isovalerate, 2-methylbutyrate, and isobutyrate, respectively, as end products. Energy generated through the fermentation of these amino acids is utilized to prolong cell survival under conditions of growth substrate starvation.

Anaerobic spirochete from a deep-sea hydrothermal vent.

An obligately anaerobic spirochete, designated strain GS-2, was selectively isolated from samples collected at a deep-sea (2,550 m) hydrothermal vent of the Galapagos Rift ocean floor spreading center. The morphological and physiological characteristics of strain GS-2 resembled those of Spirochaeta strains. However, strain GS-2 failed to grow consistently in any liquid medium tested.

Physiological diversity of rumen spirochetes.

Bovine rumen fluid contained relatively large numbers of spirochetes capable of fermenting polymers commonly present in plant materials. Polymers such as xylan, pectin, and arabinogalactan served as fermentable substrates for the spirochetes, whereas cellulose did not. Furthermore, spirochetes cultured from rumen fluid utilized as growth substrates hydrolysis products of plant polymers (e.

Branched-chain amino acid fermentation by a marine spirochete: strategy for starvation survival.

An anaerobic marine spirochete (strain MA-2) fermented glucose and formed ethanol, acetic acid, CO(2), and H(2) as end products. The organism required carbohydrates as growth substrates. Amino acids did not support the growth of strain MA-2.

Adenosine 5'-triphosphate- yielding pathways of branched-chain amino acid fermentation by a marine spirochete.

The metabolic pathways utilized by an obligately anaerobic marine spirochete (strain MA-2) to ferment branched-chain amino acids were studied. The spirochete catabolized l-leucine to isovaleric acid, l-isoleucine to 2-methylbutyric acid, and l-valine to isobutyric acid, with accompanying CO(2) production in each fermentation. Cell extracts of spirochete MA-2 converted l-leucine, l-isoleucine, and l-valine to 2-ketoisocaproic, 2-keto-3-methylvaleric, and 2-ketoisovaleric acids, respectively, through mediation of 2-ketoglutarate-dependent aminotransferase activities.

Rifampin as a selective agent for isolation of oral spirochetes.

Spirochetes indigenous to the healthy gingival crevice of the human mouth were isolated directly from colonies in agar medium containing rifampin as a selective agent.

Treponema bryantii sp. nov., a rumen spirochete that interacts with cellulolytic bacteria.

A saccharolytic spirochete that associated and interacted with cellulolytic bacteria was isolated from bovine rumen fluid. Isolation was accomplished by means of a procedure involving serial dilution of a sample of rumen fluid into a cellulose-containing agar medium. Clear zones appeared within the medium as a result of cellulose hydrolysis by rumen bacteria.