Plant biomass represents a renewable feedstock that has not yet been fully tapped because of the difficulty in accessing the carbon in its structural biopolymers. Lignin is an especially challenging substrate, but select microbes have evolved complex systems of enzymes for its breakdown through a radical-mediated oxidation process. Fungal systems are well-characterized for their ability to depolymerize lignin, but the ability of bacteria to react with this substrate remains elusive. We have therefore focused on elucidating strategies used by lignin-reactive soil bacteria and describing their oxidative enzyme systems. We now report the identification and characterization of an unusual C-type dye-decolorizing peroxidase from Amycolatopsis sp. 75iv2 (DyP2), which belongs to a family of heme peroxidases reported to be involved in bacterial lignin degradation. Biochemical studies indicate that DyP2 has novel function for this family, with versatile and high activity both as a peroxidase and Mn peroxidase (k(cat)/K(M) ≈ 10(5)-10(6) M(-1) s(-1)). It also has a Mn-dependent oxidase mode of action that expands its substrate scope. Crystallographic studies of DyP2 at 2.25 Å resolution show the existence of a Mn binding pocket and support its key role in catalysis.

No abstract

No abstract

The economic impact of infectious bovine keratoconjunctivitis (IBK) warrants continued investigation of the mechanisms by which Moraxella bovis survives on and colonizes the corneal surface. Virulent strains of M bovis produce hemolysin and exhibit different plasmid profiles than nonvirulent strains. Interactions among host, environment, vector, season, and concurrent infection influence the prevalence of IBK. Mycoplasma sp. or infectious bovine rhinotracheitis virus may enhance or hasten the disease process. The manifestations of IBK may range from mild conjunctivitis to severe ulceration, corneal perforation, and blindness. Treatment of IBK is dictated by economic considerations, intended animal use, and feasibility of administration. Antibiotic therapy is aimed at achieving drug concentrations in tears to meet or exceed the minimum inhibitory concentration for prolonged periods. At present, IBK is not a preventable disease. Affected animals must be separated from the herd and vector control vigorously instituted. Carrier animals must be identified and removed from the herd. Vaccination trials have been unsuccessful because of pili antigen crossreactivity, variable strains, and uncontrolled environmental factors. Recent investigations have determined that M bovis may utilize host iron sources via iron-repressible outer membrane proteins and siderophores for growth. Elucidation of normal defense mechanisms of the bovine eye may lead to new strategies to enhance the immune response against M bovis.Key words: Bovine pinkeye; IBK.he first reports of infectious bovine keratoconjunctivitis EpizoologyAlthough M bovis is the pathogen most commonly isolated from IBK, various factors are involved with the pathogenesis of this disease. The environment, season, concurrent pathogens, M bovis strain, and host immune system play integral roles in the occurrence and clinical severity of IBK. IBK is a highly contagious disease that spreads rapidly within a herd.6 The yearly and seasonal prevalence of the disease in different geographic regions varies greatly.l0." The isolation rate of M bovis infection gradually increases during the spring (21.4%) and summer (29.3%) months to reach a maximum in the fall at 45%.12 Peak IBK prevalence is preceded by the highest values of ultraviolet (UV) radiation.I3J4 IBK can occur during any time of the year, but outbreaks are more common during summer months. Nonetheless, heavy snowfall and UV radiation have been individually associated with outbreaks of IBK.M. bovis is spread by direct contact, nasal and ocular discharges, and by mechanical vectors. The most important vector is considered to be the face fly (Musca a~turnnalis).~~ The house fly (Musca dornestica) and barn fly (Stomoxys calcitrans) may also transport the organism. In addition to physically irritating the eye, insects may harbor the organism on their legs for up to 3 days.Is A positive correlation exists between the number of flies per animal and M bovis infection,I8 and disease prevalence is reduced by rigorous fly control pr...

Bacteria and other living organisms offer a potentially unlimited resource for the discovery of new chemical catalysts, but many interesting reaction phenotypes observed at the whole organism level remain difficult to elucidate down to the molecular level. A key challenge in the discovery process is the identification of discrete molecular players involved in complex biological transformations because multiple cryptic genetic components often work in concert to elicit an overall chemical phenotype. We now report a rapid pipeline for the discovery of new enzymes of interest from unsequenced bacterial hosts based on laboratory-scale methods for the de novo assembly of bacterial genome sequences using short reads. We have applied this approach to the biomass-degrading soil bacterium Amycolatopsis sp. 75iv2 ATCC 39116 (formerly Streptomyces setonii and S. griseus 75vi2) to discover and biochemically characterize two new heme proteins comprising the most abundant members of the extracellular oxidative system under lignin-reactive growth conditions.

Magnetotactic bacteria have evolved complex subcellular machinery to construct linear chains of magnetite nanocrystals that allow the host cell to sense direction. Each mixed-valent iron nanoparticle is mineralized from soluble iron within a membrane-encapsulated vesicle termed the magnetosome, which serves as a specialized compartment that regulates the iron, redox, and pH environment of the growing mineral. To dissect the biological components that control this process, we have carried out a genetic and biochemical study of proteins proposed to function in iron mineralization. In this study, we show that the redox sites of c-type cytochromes of the Magnetospirillum magneticum AMB-1 magnetosome island, MamP and MamT, are essential to their physiological function and that ablation of one or both heme motifs leads to loss of function, suggesting that their ability to carry out redox chemistry in vivo is important. We also develop a method to heterologously express fully heme-loaded MamP from AMB-1 for in vitro biochemical studies, which show that its Fe(III)-Fe(II) redox couple is set at an unusual potential (−89 ± 11 mV) compared with other related cytochromes involved in iron reduction or oxidation. Despite its low reduction potential, it remains competent to oxidize Fe(II) to Fe(III) and mineralize iron to produce mixed-valent iron oxides. Finally, in vitro mineralization experiments suggest that Mms mineral-templating peptides from AMB-1 can modulate the iron redox chemistry of MamP.

Summary: Micro‐organisms isolated from rhizospheres and rhizoplanes of wheat plants, and from root‐free soil, produced growth regulating substances with the properties of gibberellins and indolyl‐3‐acetic acid (IAA). Substances inhibiting extensions of pea plant internodes and lettuce hypocotyls were also produced, especially by bacteria from the root region of seedlings 6 days old. Bacteria producing growth promoting substances were most abundant on roots of older plants. Seedlings grown aseptically with added gibberellic acid (GA3) and IAA, or grown with a soil inoculum, developed similarly and differed in their morphology from those grown aseptically without additives.

Illustrates alternative “green” strategies to indicate possible reactions of the hotel sector to the environmental issue and the extent of the “greening” process on the control system. Discusses the results of a questionnaire survey into the environmental standing of an hotel and the control system used to appraise the hotel manager. Analysis is based on comparison of hotel managers operating with an environmental policy and those managers operating without. Tentative conclusions drawn would indicate that although a number of companies have adopted an environmental policy, in general, the hotel sector is not taking a proactive approach to environmental concerns.