Diversity of benzyl- and alkylsuccinate synthase genes in hydrocarbon-impacted environments and enrichment cultures.

Hydrocarbon-degrading microorganisms play an important role in the natural attenuation of spilled petroleum in a variety of anoxic environments. The role of benzylsuccinate synthase (BSS) in aromatic hydrocarbon degradation and its use as a biomarker for field investigations are well documented. The recent discovery of alkylsuccinate synthase (ASS) allows the opportunity to test whether its encoding gene, assA, can serve as a comparable biomarker of anaerobic alkane degradation.

Cloning and characterization of monofunctional catalase from photosynthetic bacterium Rhodospirillum rubrum S1.

In this study, an approx. 2.5-kb gene fragment including the catalase gene from Rhodospirillum rubrum S1 was cloned and characterized.

Biogeography of actinomycete communities and type II polyketide synthase genes in soils collected in New Jersey and Central Asia.

Soil microbial communities are believed to be comprised of thousands of different bacterial species. One prevailing idea is that "everything is everywhere, and the environment selects," implying that all types of bacteria are present in all environments where their growth requirements are met. We tested this hypothesis using actinomycete communities and type II polyketide synthase (PKS) genes found in soils collected from New Jersey and Uzbekistan (n = 91).

Microbial dioxygenase gene population shifts during polycyclic aromatic hydrocarbon biodegradation.

The degradation of polycyclic aromatic hydrocarbons (PAHs) by bacteria has been widely studied. While many pure cultures have been isolated and characterized for their ability to grow on PAHs, limited information is available on the diversity of microbes involved in PAH degradation in the environment. We have designed generic PCR primers targeting the gene fragment encoding the Rieske iron sulfur center common to all PAH dioxygenase enzymes.

Effect of carbon starvation on toluene degradation activity by toluene monooxygenase-expressing bacteria.

Subsurface bacteria commonly exist in a starvation state with only periodic exposure to utilizable sources of carbon and energy. In this study, the effect of carbon starvation on aerobic toluene degradation was quantitatively evaluated with a selection of bacteria representing all the known toluene oxygenase enzyme pathways. For all the investigated strains, the rate of toluene biodegradation decreased exponentially with starvation time.

Identification of unique type II polyketide synthase genes in soil.

Many bacteria, particularly actinomycetes, are known to produce secondary metabolites synthesized by polyketide synthases (PKS). Bacterial polyketides are a particularly rich source of bioactive molecules, many of which are of potential pharmaceutical relevance. To directly access PKS gene diversity from soil, we developed degenerate PCR primers for actinomycete type II KS(alpha) (ketosynthase) genes.

Quantitative structure-activity relationship (QSAR) analysis of aromatic effector specificity in NtrC-like transcriptional activators from aromatic oxidizing bacteria.

A quantitative structure-activity relationship (QSAR) approach was taken to provide mechanistic insights into the interaction between the chemical structure of inducing compounds and the transcriptional activation of aromatic monooxygenase operons among the XylR/DmpR subclass of bacterial NtrC-like transcriptional regulators. Compared to XylR and DmpR, a broader spectrum of effector compounds was observed for the TbuT system from Ralstonia pickettii PKO1. The results of QSAR analysis for TbuT suggested that a steric effect, rather than hydrophobic or electronic effects, may be the predominant factor in determining aromatic effector specificity, and the active site of the regulator may positively interact not only with the methyl moiety but also with the most electron-rich aryl side of an aromatic effector.

Characterization of the adaptive response to trichloroethylene-mediated stresses in Ralstonia pickettii PKO1.

In Ralstonia pickettii PKO1, a denitrifying toluene oxidizer that carries a toluene-3-monooxygenase (T3MO) pathway, the biodegradation of toluene and trichloroethylene (TCE) by the organism is induced by TCE at high concentrations. In this study, the effect of TCE preexposure was studied in the context of bacterial protective response to TCE-mediated toxicity in this organism. The results of TCE degradation experiments showed that cells induced by TCE at 110 mg/liter were more tolerant to TCE-mediated stress than were those induced by TCE at lower concentrations, indicating an ability of PKO1 to adapt to TCE-mediated stress.

Physiological and cellular responses of the 2,4-D degrading bacterium, Burkholderia cepacia YK-2, to the phenoxyherbicides 2,4-D and 2,4,5-T.

Our previous research has demonstrated that novel 43-kDa DnaK and 41-kDa GroEL proteins are synthesized in Burkholderia sp. YK-2 in response to sublethal concentrations of 2,4-D stress [Cho et al. (2000) Curr Microbiol 41:33-38].

The transformation of Saperda calcarata (Coleoptera: Cerambycidae) into a cellulose digester through the inclusion of fungal enzymes in its diet.

The larvae of the aspen borer, Saperda calcarata, which feed on the inner bark and sapwood of living aspen stems, are unable to digest cellulose. However, they can be transformed into cellulose digesters by adding the active cellulase complex of the fungus, Penicillium funiculosum to their diet. S.

The effect of acquired microbial enzymes on assimilation efficiency in the common woodlouse, Tracheoniscus rathkei.

The digestive tract of the common woodlouse, Tracheoniscus rathkei Brandt (Isopoda: Oniscoidea), contains digestive enzymes active against α-1,4-glucans, which are the chief storage polysaccharides of vascular plants, algae, fungi, and animals, and β-1,3-glucans, which are present in algae and fungi. Digestive tract extracts also exhibit significant activity toward xylan and carboxymethyl-cellulose but negligible activity toward microcrystalline cellulose, substrates representative of the major structural polysaccharides of vascular plants. Low activity was detected toward pectin, and no activity was detected toward chitin.