Characterization of a methane-utilizing bacterium from a bacterial consortium that rapidly degrades trichloroethylene and chloroform.

A mixed culture of bacteria grown in a bioreactor with methane as a carbon and energy source rapidly oxidized trichloroethylene and chloroform. The most abundant organism was a crescent-shaped bacterium that bound the fluorescent oligonucleotide signature probes that specifically hybridize to serine pathway methylotrophs. The 5S rRNA from this bacterium was found to be 93.

Soluble methane monooxygenase component B gene probe for identification of methanotrophs that rapidly degrade trichloroethylene.

Restriction fragment length polymorphisms, Western blot (immunoblot) analysis, and fluorescence-labelled signature probes were used for the characterization of methanotrophic bacteria as well as for the identification of methanotrophs which contained the soluble methane monooxygenase (MMO) gene and were able to degrade trichloroethylene (TCE). The gene encoding a soluble MMO component B protein from Methylosinus trichosporium OB3b was cloned. It contained a 2.

Biodegradation of low-molecular-weight halogenated hydrocarbons by methanotrophic bacteria.

Low-molecular-weight halogenated hydrocarbons are susceptible to degradation by anaerobic and aerobic bacteria. The methanotrophic bacterium Methylosinus trichosporium 0B3b degrades trichloroethylene more rapidly than other bacteria examined to date. Expression of soluble methane monooxygenase (MMO) is correlated with high rates of biodegradation.

Use of oligodeoxynucleotide signature probes for identification of physiological groups of methylotrophic bacteria.

Oligodeoxynucleotide sequences that uniquely complemented 16S rRNAs of each group of methylotrophs were synthesized and used as hybridization probes for the identification of methylotrophic bacteria possessing the serine and ribulose monophosphate (RuMP) pathways for formaldehyde fixation. The specificity of the probes was determined by hybridizing radiolabeled probes with slot-blotted RNAs of methylotrophs and other eubacteria followed by autoradiography. The washing temperature was determined experimentally to be 50 and 52 degrees C for 9-alpha (serine pathway) and 10-gamma (RuMP pathway) probes, respectively.

16S ribosomal RNA sequence analysis for determination of phylogenetic relationship among methylotrophs.

16S ribosomal RNAs (rRNA) of 12 methylotrophic bacteria have been almost completely sequenced to establish their phylogenetic relationships. Methylotrophs that are physiologically related are phylogenetically diverse and are scattered among the purple eubacteria (class Proteobacteria). Group I methylotrophs can be classified in the beta- and the gamma-subdivisions and group II methylotrophs in the alpha-subdivision of the purple eubacteria, respectively.

Optimization of trichloroethylene oxidation by methanotrophs and the use of a colorimetric assay to detect soluble methane monooxygenase activity.

Methylosinus trichosporium OB3b biosynthesizes a broad specificity soluble methane monooxygenase that rapidly oxidizes trichloroethylene (TCE). The selective expression of the soluble methane monooxygenase was followed in vivo by a rapid colorimetric assay. Naphthalene was oxidized by purified soluble methane monooxygenase or by cells grown in copper-deficient media to a mixture of 1-naphthol and 2-naphthol.

Biodegradation of trichloroethylene by Methylosinus trichosporium OB3b.

The methanotroph Methylosinus trichosporium OB3b, a type II methanotroph, degraded trichloroethylene at rates exceeding 1.2 mmol/h per g (dry weight) following the appearance of soluble methane monooxygenase in continuous and batch cultures. Cells capable oxidizing trichloroethylene contained components of soluble methane monooxygenase as demonstrated by Western blot (immunoblot) analysis with antibodies prepared against the purified enzyme.

Initial stages in the morphogenesis of nitrogen-fixing stem nodules of Sesbania rostrata.

Morphogenesis of stem nodules in Sesbania rostrata was studied over a period of 6 days after inoculation with an appropriate species of Rhizobium. Nodulation sites were initially slightly raised, circular areas 0.3 to 0.

Lectin in five soybean cultivars previously considered to be lectin-negative.

Hemagglutinating proteins were isolated by affinity chromatography from seeds of each of five cultivars of soybeans (Clycine max (L.) Merr.) previously reported to lack detectable lectin (S.

Nucleoid structure in freeze fractures of Streptococcus faecalis: effects of filtration and chilling.

With the techniques used in this study, the nucleoid of Streptococcus faecalis could not be seen in freeze-etch preparations unless glutaraldehyde had been added to cultures of cells before they were frozen. With time, the nucleoid became visible as a network of fibers, apparently as a result of the aggregation of individual chromosomal elements in the presence of glutaraldehyde. When glutaraldehyde was added to undisturbed cultures, the fibers that became visible were observed in small patches that were seemingly scattered throughout the cytoplasm.

Localization and partial characterization of soybean lectin-binding polysaccharide of Rhizobium japonicum.

Immunoelectron microscopy was combined with partial characterization of isolated exopolysaccharide to study binding of soybean lectin by Rhizobium japonicum strain USDA 138. Lectin-binding activity resided in two forms of exopolysaccharide produced during growth: an apparently very high-molecular-weight capsular form and a lower-molecular-weight diffusible form. At low-speed centrifugation, the capsular form cosedimented with cells to form a viscous, white, cell-gel complex which was not diffusible in 1% agar, and the diffusible form remained in the cell-free supernatant.

Evidence that Streptococcus mutans constructs its membrane with excess fluidity for survival at suboptimal temperatures.

When cells from cultures of Streptococcus mutans strain FA-1 grown at 37 degrees C were exposed to incubation temperatures of 26 degrees C or less for 5 min or more, an extensive aggregation of particles was observed on the convex fracture faces of their freeze-cleaved membranes. Aggregation of particles was accompanied by a parallel increase in the activation energy for growth. By shifting the growth temperature from 37 to 24 degrees C for one doubling of culture mass, the transition temperature for membrane particle aggregation could be lowered from about 26 to 0 degrees C.

Accumulation of Soybean Lectin-Binding Polysaccharide During Growth of Rhizobium japonicum as Determined by Hemagglutination Inhibition Assay.

A hemagglutination inhibition assay was used to estimate the presence of soybean lectin-binding polysaccharide in whole culture, culture supernatant, and isolated exopolysaccharide of Rhizobium japonicum USDA 138. The occurrence of 0.1 to 0.

Structural arrangement of polymers within the wall of Streptococcus faecalis.

The structure of the cell wall of Streptococcus faecalis was studied in thin sections and freeze fractures of whole cells and partially purified wall fractions. Also, the structures of wall preparations treated with hot trichloroacetic acid to remove non-peptidoglycan wall polymers were compared with wall preparations that possess a full complement of accessory polymers. The appearance of the wall varied with the degree of hydration of preparations and physical removal of the cell membrane from the wall before study.

Viability of Rhizobium bacteroids.

Bacteroids prepared from nodules of soybean and bean were tested for viability. Contrary to the prevailing view that bacteroids are nonviable, it was found that bacteroids averaged 90% viability, irrespective of Rhizobium strain, nodule age, or nodule environment.

Polarity in the exponential-phase Rhizobium japonicum cell.

Highly distinctive aspects of the exponentail-phase Rhizobium japonicum cell were disclosed by means of thin sections, freeze etching, fluorescent antibodies, and ruthenium red staining. Polarity was expressed in the form of reserve polymer distribution near one end of the cell and as cytoplasmic localization near the opposite end. In addition, exocellular polysaccharide (EPS) accumulated preferentially around the cytoplasmic end, and the feature described previously as an "immunofluorescent polar tip" was seen clearly as an extracellular polar body (EPB) on the tip of the cell at the reserve polymer end.

Organization of mesosomes in fixed and unfixed cells.

After the addition of glutaraldehyde (GA) to cells incubated at 3 or 37 degrees C, mesosomes were observed with increasing frequencies in freeze fractures of cells. These increases were related to the kinetics with which GA cross-linked adjacent amino acids. Upon the addition of GA, mesosomes were first observed in the periphery of freeze-fractured cells usually attached to septal membranes.

Effect of temperature on the distribution of membrane particles in Streptococcus faecalis as seen by the freeze-fracture technique.

When cells of Streptococcus faecalis ATCC 9790 were incubated at temperatures above 10 C before being frozen for freeze-fracture, a random distribution of particles was observed on the outer fracture face of the freeze-cleaved cell membrane. However, when cells were incubated below 10 C before freezing, particleless patches were seen on this membrane surface. The size of the patches produced on chilling could be increased by centrifugation or by storing the chilled cells overnight at about 3 C.