A polyesterase from the Antarctic bacterium Moraxella sp. degrades highly crystalline synthetic polymers

The uncontrolled release of plastics in the environment has rendered them ubiquitous around the planet, threatening the wildlife and human health. Biodegradation and valorization of plastics has emerged as an eco-friendly alternative to conventional management techniques. Discovery of novel polymer-degrading enzymes with diversified properties is hence an important task in order to explore different operational conditions for plastic-waste upcycling. In the present study, a barely studied psychrophilic enzyme (MoPE) from the Antractic bacterium Moraxella sp. was heterologously expressed, characterized and its potential in polymer degradation was further investigated. Based on its amino acid composition and structure, MoPE resembled PET-degrading enzymes, sharing features from both mesophilic and thermophilic homologues. MoPE hydrolyzes non-biodegradable plastics, such as polyethylene terephthalate and polyurethane, as well as biodegradable synthetic polyesters, such as polycaprolactone, polyhydroxy butyrate, polybutylene succinate and polylactic acid. The mass fraction crystallinity of the aliphatic polymers tested ranged from 11% to 64% highlighting the potential of the enzyme to hydrolyze highly crystalline plastics. MoPE was able to degrade different types of amorphous and semi-crystalline PET, releasing water-soluble monomers and showed synergy with a feruloyl esterase of the tannase family for the release of terephthalic acid. Based on the above, MoPE was characterized as a versatile psychrophilic polyesterase demonstrating a broad-range plastics degradation potential.

Interspecies Outer Membrane Vesicles (OMVs) Modulate the Sensitivity of Pathogenic Bacteria and Pathogenic Yeasts to Cationic Peptides and Serum Complement

The virulence of bacterial outer membrane vesicles (OMVs) contributes to innate microbial defense. Limited data report their role in interspecies reactions. There are no data about the relevance of OMVs in bacterial-yeast communication. We hypothesized that model Moraxella catarrhalis OMVs may orchestrate the susceptibility of pathogenic bacteria and yeasts to cationic peptides (polymyxin B) and serum complement. Using growth kinetic curve and time-kill assay we found that OMVs protect Candida albicans against polymyxin B-dependent fungicidal action in combination with fluconazole. We showed that OMVs preserve the virulent filamentous phenotype of yeasts in the presence of both antifungal drugs. We demonstrated that bacteria including Haemophilus influenza, Acinetobacter baumannii, and Pseudomonas aeruginosa coincubated with OMVs are protected against membrane targeting agents. The high susceptibility of OMV-associated bacteria to polymyxin B excluded the direct way of protection, suggesting rather the fusion mechanisms. High-performance liquid chromatography-ultraviolet spectroscopy (HPLC-UV) and zeta-potential measurement revealed a high sequestration capacity (up to 95%) of OMVs against model cationic peptide accompanied by an increase in surface electrical charge. We presented the first experimental evidence that bacterial OMVs by sequestering of cationic peptides may protect pathogenic yeast against combined action of antifungal drugs. Our findings identify OMVs as important inter-kingdom players.

Biodegradation of Tributyltin (TBT) by Extremophile Bacteria from Atacama Desert and Speciation of Tin By-products

Biodegradation of tributyltin (TBT) by four tin resistant Gram negative bacteria isolated from extremely contaminated river sediments in the Atacama Desert in Chile was studied. Moraxella osloensis showed the greatest resistance and degradation capability of TBT, producing less toxic by-products, such as dibutyltin (DBT) and inorganic tin. In 7 days, approximately 80 % of TBT degradation was achieved, generating close to 20 % of DBT as degradation product. The degradation rate constant (k) was 0.022 [day(-1)] and TBT half-life (t1/2) in culture was 4.3 days. Debutylation is stated a probable mechanism of TBT degradation.

Fermentation products of solvent tolerant marine bacterium Moraxella spp. MB1 and its biotechnological applications in salicylic acid bioconversion

As part of a proactive approach to environmental protection, emerging issues with potential impact on the environment is the subject of ongoing investigation. One emerging area of environmental research concerns pharmaceuticals like salicylic acid, which is the main metabolite of various analgesics including aspirin. It is a common component of sewage effluent and also an intermediate in the degradation pathway of various aromatic compounds which are introduced in the marine environment as pollutants. In this study, biotransformation products of salicylic acid by seaweed, Bryopsis plumosa, associated marine bacterium, Moraxella spp. MB1, have been investigated. Phenol, conjugates of phenol and hydroxy cinnamic acid derivatives (coumaroyl, caffeoyl, feruloyl and trihydroxy cinnamyl) with salicylic acid (3-8) were identified as the bioconversion products by electrospray ionization mass spectrometry. These results show that the microorganism do not degrade phenolic acid but catalyses oxygen dependent transformations without ring cleavage. The degradation of salicylic acid is known to proceed either via gentisic acid pathway or catechol pathway but this is the first report of biotransformation of salicylic acid into cinnamates, without ring cleavage. Besides cinnamic acid derivatives (9-12), metabolites produced by the bacterium include antimicrobial indole (13) and β-carbolines, norharman (14), harman (15) and methyl derivative (16), which are beneficial to the host and the environment.

Novel detection of Escherichia coli beta-D-glucuronidase activity using a microbially-modified glassy carbon electrode and its potential for faecal pollution monitoring

The electrochemical detection of Escherichia coli beta-D-glucuronidase activity as a means of monitoring water pollution by faecal material was investigated using separate Moraxella- and Pseudomonas putida-modified glassy carbon electrodes. The former was more sensitive and selective. The Moraxella-modified biosensor was 100 times more rapid and sensitive than the spectrophotometric detection of beta-D-glucuronidase activity. The experimental limit of detection of the biosensor was two c.f.u. per 100 ml polluted water sample within 20 min. The biosensor gave a linear response to commercial beta-D-glucuronidase concentration between 0.2 ng and 2 microg ml(-1). The biosensor detected activity of beta-D-glucuronidase from viable but non-culturable (VBNC) cells and can therefore serve as a presence or absence device for rapid water quality monitoring.

Biotransformation of citrinin to decarboxycitrinin using an organic solvent-tolerant marine bacterium, Moraxella sp. MB1

Organic solvent tolerant microorganisms (OSTMs) are novel group of extremophilic microorganisms that have developed resistance to withstand solvent toxicity. These organisms play an important role in biotransformation of organic compounds. In the present study, we used an organic solvent-tolerant marine bacterium, Moraxella sp. MB1. 16S rRNA sequencing revealed that the bacterium shows 98% similarity with an uncultured marine bacterium with GenBank accession no. AY936933. This bacterium was used for the transformation of a toxin, citrinin, into decarboxycitrinin in a biphasic system. This transformation was affected by decarboxylase enzyme produced by MB1. Transformation of citrinin to decarboxycitrinin was monitored by thin-layer chromatography (TLC) and spectrophotometrically. Citrinin decarboxylase activity responsible for transformation was studied in cell-free growth medium and cell lysate of Moraxella sp. MB1. Citrinin decarboxylase was found to be intracellular in nature. The biotransformed product was purified and identified as decarboxycitrinin using electrospray ionization mass spectrometry (ESI-MS/MS) and nuclear magnetic resonance (NMR) spectrometry. The antibiotic activity of both citrinin and decarboxycitrinin is also reported.

Stress-survival responses of a carbon-starvedp-nitrophenol-mineralizingMoraxellastrain in river water

The effect of carbon starvation on the stress-resistant responses of a p-nitrophenol-mineralizing Moraxella strain was examined in both buffer and river water samples. The Moraxella strain showed optimal stress-resistant responses in a minimal salt buffer when carbon-starved for 1–2 d. In the buffer system, the 1- and 2-day carbon-starved Moraxella cultures survived about 150-, 200-, and 100-fold better than the non-starved cultures when exposed to 43.5 °C, 2.7 mol/L NaCl, and 500 µmol/L H2O2for 4 h, respectively. A green fluorescent protein gene- (gfp) labelled derivative of the Moraxella strain was used to examine the stress-resistant responses of the bacterium in natural river water microcosms. The carbon-starved gfp-labelled Moraxella strain also showed stress-resistant responses against heat, osmotic, and oxidative stresses in the river water samples. Despite the stress-tolerant capability of the carbon-starved gfp-labelled Moraxella cells, they did not exhibit any survival advantage over their non-starved counterparts when inoculated into river water microcosms and incubated at 10 and 22 °C for 14 d.Key words: carbon starvation, stress-survival responses, Moraxella, p-nitrophenol, green fluorescent protein gene.

Effect of carbon starvation on p-nitrophenol degradation by a Moraxella strain in buffer and river water

This study examines the effect of carbon starvation on the ability of a Moraxella sp. strain to degrade p-nitrophenol (PNP). Carbon starvation for 24 h decreased the induction time for p-nitrophenol degradation by the bacterium in a minimal salt medium from 6 to 1 h but it did not completely eliminate the induction time. Moraxella cells with 2-day carbon starvation had an induction time of 3 h and the induction time of the 3-day starved cells was 6 h. A 100% increase in density of the non-starved cells did not affect the induction time for p-nitrophenol degradation by the bacterium, indicating that the initial increase in cell density of the carbon-starved culture did not cause the faster onset of p-nitrophenol degradation. However, the initial uptake of p-nitrophenol of the 1-day carbon-starved Moraxella cells was 3-fold higher than the non-starved cells. A green fluorescent protein gene (gfp)-labelled Moraxella (M6 strain) was constructed to examine the survival of and p-nitrophenol degradation by the bacterium in non-sterile river water samples. Similar p-nitrophenol degradation behaviour was observed in the river water samples inoculated with the M6 cells. The time needed for complete degradation of p-nitrophenol by the non-starved M6 was 19-27 and 33 h in samples spiked with 80, 200 and 360 microM p-nitrophenol, respectively. However, the 1-day carbon-starved inocula required about 16 h to degrade the p-nitrophenol completely regardless of its concentration in the water samples. Survival of the carbon-starved and non-starved M6 was not significantly different from each other in the river water regardless of the p-nitrophenol concentration. In the absence of p-nitrophenol, the inoculum density decreased continuously. At 200 and 360 microM p-nitrophenol, the cell densities of M6 increased in the first two days of incubation and declined steadily afterward.

Transfer of the misnamed [Alysiella] sp. IAM 14971 (=ATCC 29468) to the genus Moraxella as Moraxella oblonga sp. nov

Phylogenetic analysis based on 16S rRNA gene sequences revealed that [Alysiella] sp. IAM 14971 (=ATCC 29468) is closely related to the genus Moraxella of the γ-Proteobacteria (96–97 % similarity). The newly obtained phenotypic data also indicate that [Alysiella] sp. IAM 14971 is distinct from the genus Alysiella and similar to the genus Moraxella. On the basis of these results, the strain should be classified in the genus Moraxella, as Moraxella oblonga sp. nov. The type strain is IAM 14971T (=ATCC 29468T).

Characterization of the first molluscicidal lipopolysaccharide from Moraxella osloensis

Moraxella osloensis is a bacterium that is mutualistically associated with Phasmarhabditis hermaphrodita, a nematode that has potential for the biocontrol of mollusk pests, especially the slug Deroceras reticulatum. We discovered that purified M. osloensis lipopolysaccharide (LPS) possesses a lethal toxicity to D. reticulatum when administered by injection but no contact or oral toxicity to this slug. The toxicity of the LPS resides in the lipid A moiety. M. osloensis LPS was semiquantitated at 6 x 10(7) endotoxin units per mg. The LPS is a rough-type LPS with an estimated molecular weight of 5,300. Coinjection of galactosamine with the LPS increased the LPS's toxicity to the slug two- to four-fold. The galactosamine-induced sensitization of the slug to the LPS was reversed completely by uridine.

A high-molecular-weight outer membrane protein of Xanthomonas oryzae pv. oryzae exhibits similarity to non-fimbrial adhesins of animal pathogenic bacteria and is required for optimum virulence

Transposon insertions in a novel 3.798 kb open reading frame (ORF) of the rice pathogen, Xanthomonas oryzae pv. oryzae (Xoo) cause virulence deficiency and altered colony/lawn morphology. This ORF encodes a protein, XadA, of 1,265 amino acids that exhibits significant similarity to non-fimbrial adhesins of animal pathogenic bacteria such as Yersinia YadA and Moraxella UspA1. An interesting feature is that the YadA similarity region is repeated six times within the XadA sequence and encompasses almost the entire length of the protein. Anti-XadA antibodies identified a 110 kDa outer membrane protein that was sensitive to protease treatment of whole cells. XadA expression is induced in minimal medium. Homology modelling suggests that XadA adopts a beta-helix conformation-like pertactin, a non-fimbrial adhesin of Bordetella pertussis. This work is the first characterization of a non-fimbrial adhesin-like molecule in a plant pathogenic bacterium. It extends our knowledge about the repertoire of homologous virulence factors that are deployed by animal and plant pathogenic bacteria to include functions potentially involved in adhesion.

Endotoxin activity of Moraxella osloensis against the grey garden slug, Deroceras reticulatum

Moraxella osloensis is a gram-negative bacterium associated with Phasmarhabditis hermaphrodita, a slug-parasitic nematode that has prospects for biological control of mollusk pests, especially the grey garden slug, Deroceras reticulatum. This bacterium-feeding nematode acts as a vector that transports M. osloensis into the shell cavity of the slug, and the bacterium is the killing agent in the nematode-bacterium complex. We discovered that M. osloensis produces an endotoxin(s), which is tolerant to heat and protease treatments and kills the slug after injection into the shell cavity. Washed or broken cells treated with penicillin and streptomycin from 3-day M. osloensis cultures were more pathogenic than similar cells from 2-day M. osloensis cultures. However, heat and protease treatments and 2 days of storage at 22 degrees C increased the endotoxin activity of the young broken cells but not the endotoxin activity of the young washed cells treated with the antibiotics. This suggests that there may be a proteinaceous substance(s) that is structurally associated with the endotoxin(s) and masks its toxicity in the young bacterial cells. Moreover, 2 days of storage of the young washed bacterial cells at 22 degrees C enhanced their endotoxin activity if they were not treated with the antibiotics. Furthermore, purified lipopolysaccharide (LPS) from the 3-day M. osloensis cultures was toxic to slugs, with an estimated 50% lethal dose of 48 microg per slug, thus demonstrating that the LPS of M. osloensis is an endotoxin that is active against D. reticulatum. This appears to be the first report of a biological toxin that is active against mollusks.

The use of silica gel prepared by sol-gel method and polyurethane foam as microbial carriers in the continuous degradation of phenol

A mixed microbial culture was immobilized by entrapment into silica gel (SG) and entrapment/ adsorption on polyurethane foam (PU) and ceramic foam. The phenol degradation performance of the SG biocatalyst was studied in a packed-bed reactor (PBR), packed-bed reactor with ceramic foam (PBRC) and fluidized-bed reactor (FBR). In continuous experiments the maximum degradation rate of phenol (q(s)max) decreased in the order: PBRC (598 mg l(-1) h(-1)) > PBR (PU, 471 mg l(-1)h(-1)) > PBR(SG, 394 mg l(-1) h(-1)) > FBR (PU, 161 mg l(-1) h(-1)) > FBR (SG, 91 mg l(-1) h(-1)). The long-term use of the SG biocatalyst in continuous phenol degradation resulted in the formation of a 100-200 microm thick layer with a high cell density on the surface of the gel particles. The abrasion of the surface layer in the FBR contributed to the poor degradation performance of this reactor configuration. Coating the ceramic foam with a layer of cells immobilized in colloidal SiO2 enhanced the phenol degradation efficiency during the first 3 days of the PBRC operation, in comparison with untreated ceramic packing.

Using a green fluorescent protein gene-labeled p-nitrophenol-degrading Moraxella strain to examine the protective effect of alginate encapsulation against protozoan grazing

A gfp-labeled p-nitrophenol-degrading Moraxella strain G21 was used to study grazing of a Tetrahymena thermophila strain in liquid medium. This allowed visualization of the feeding process. Under an epifluorescent microscope, individual G21 fluorescent cells could be seen in vacuoles within the protozoans. Most of the G21 cells appeared to be lysed by T. thermophila and green fluorescent protein released from the bacteria yielded brightly fluorescent food vacuoles inside the protozoans, Examination of population dynamics of a mixed culture of T. thermophila and Moraxella sp. G21 showed that the protozoan reduced the bacterial density from 7.6 to 5.8 log CFU/ml in 2 days. Encapsulating the bacteria in alginate prevented grazing by the protozoans and the density of G21 cells in the beads increased steadily from about 8.3 to 8.9 log CFU/ml in 15 days regardless of the presence of the protozoans.

Green fluorescent protein as a visual marker in a p-nitrophenol degrading Moraxella sp

The green fluorescent protein gene (gfp) was introduced into a p-nitrophenol-metabolizing strain of Moraxella sp. by chromosomal integration. The gfp-marked transformants, designated Moraxella sp. strains G21 and G25, exhibited green fluorescence under UV light. Molecular characterization by PCR and Southern hybridization showed the presence of gfp in both transformants. Both transformants and the parent strain degraded 720 microM of p-nitrophenol with nitrite release within 4 h after inoculation in minimal medium supplemented with yeast extract. Transformants degraded up to 1440 microM p-nitrophenol and mineralized about 60% of 720 microM p-nitrophenol, both in broth and in soil, to the same extent as the parent strain. Insertion of gfp did not adversely affect the expression of p-nitrophenol-degrading genes in the transformants. Survival studies indicated that individual green fluorescent colonies of transformants can be detected up to 2 weeks after inoculation in soil. These marked strains could be of value in studies on microbial survival in the environment.

Formation of amino acid (L-leucine, L-phenylalanine) derived volatile flavour compounds by Moraxella phenylpyruvica and Staphylococcus xylosus in cured meat model systems

A bacterial strain isolated from Danish immersion curing brine, Moraxella phenylpyruvica 0100, and a commercial meat starter culture, Staphylococcus xylosus DD34, were tested for their ability to form characteristic volatile compounds in minimal medium with the added amino acid L-leucine or L-phenylalanine under different environmental conditions (pH 5.5 and 6.0; 0 and 210 ppm nitrate; pre-incubation with and without agitation) and compared with respect to their ability to form volatile compounds in cured meat extracts and vacuum-packed cured meat cuts. The characteristic cured meat aroma precursors/compounds 3-methylbutanal and 3-methylbutanol were found to be formed in cured meat extracts and vacuum-packed cured meat cuts inoculated with M. phenylpyruvica. These volatiles are most probably formed by metabolic conversion of the amino acid L-leucine by M. phenylpyruvica, as they were also produced in minimal media with added L-leucine inoculated with this organism. The characteristic L-phenylalanine derived compound, benzaldehyde, formed by M. phenylpyruvica in minimal medium in the presence of nitrate (210 ppm), was not produced in any noticeable amount in cured meat extracts or vacuum-packed cured meat inoculated with M. phenylpyruvica. In contrast, benzacetaldehyde, which has been described as a possible metabolic product of the microbial conversion of L-phenylalanine, was found to be a characteristic volatile compound formed in cured meat extracts and vacuum-packed cured meat inoculated with M. phenylpyruvica, indicating an alternative metabolic pathway for L-phenylalanine by this organism in a cured meat environment. Even though S. xylosus was able to form volatile compounds characteristic of cured meats (3-methylbutanal, 3-methylbutanol) in minimal media with added L-leucine, this bacterial strain seemed not to be able to produce these characteristic volatiles in the studied cured meat systems. The present data imply that M. phenylpyruvica, in particular, is a potential meat starter for ensuring superior flavour development in cured meat.

Bacterial influence on the production of paralytic shellfish toxins by dinoflagellated algae

This study investigated the role of intracellular and extracellular bacteria in the production of paralytic shellfish toxins by dinoflagellated algal cells. Three strains of the toxic dinoflagellate species, Alexandrium tamarense, were purified by external bacteria using penicillin G (Pen. G) at levels of 500 and 1000 p.p.m. Levels of toxicity of the resulting purified dinoflagellate cultures were similar to those of the original strains contaminated with external bacteria, indicating that the external bacteria had no influence on toxicity. No bacterial colony forming units (cfu) arose from disruption of algal cells derived from penicillin-treated cultures, indicating that intracellular bacteria were not responsible for the toxicity of cultures.

Antibacterial activity of the phenolic acids fractions of Scrophularia frutescens and Scrophularia sambucifolia

The phenolic fractions of aerial part of Scrophularia frutescens and S. sambucifolia (Scrophulariaceae) showed a potent antibacterial activity. Ferulic, isovanillic, p-hydroxycinnamic, p-hydroxybenzoic, syringic, caffeic, gentisic and protocatechuic acids were isolated from S. frutescens and ferulic, p-coumaric, vanillic, p-hydroxibenzoic and syringic acids were isolated from S. sambucifolia. Since phenolic acids have been shown in the literature to exert an antibacterial effect, the presence of these compounds in the two plants explains their antibacterial activity.

Soil and sediment bacteria capable of aerobic nitrate respiration

Several laboratory strains of gram-negative bacteria are known to be able to respire nitrate in the presence of oxygen, although the physiological advantage gained from this process is not entirely clear. The contribution that aerobic nitrate respiration makes to the environmental nitrogen cycle has not been studied. As a first step in addressing this question, a strategy which allows for the isolation of organisms capable of reducing nitrate to nitrite following aerobic growth has been developed. Twenty-nine such strains have been isolated from three soils and a freshwater sediment and shown to comprise members of three genera (Pseudomonas, Aeromonas, and Moraxella). All of these strains expressed a nitrate reductase with an active site located in the periplasmic compartment. Twenty-two of the strains showed significant rates of nitrate respiration in the presence of oxygen when assayed with physiological electron donors. Also isolated was one member of the gram-positive genus Arthrobacter, which was likewise able to respire nitrate in the presence of oxygen but appeared to express a different type of nitrate reductase. In the four environments studied, culturable bacteria capable of aerobic nitrate respiration were isolated in significant numbers (10(4) to 10(7) per g of soil or sediment) and in three cases were as abundant as, or more abundant than, culturable bacteria capable of denitrification. Thus, it seems likely that the corespiration of nitrate and oxygen may indeed make a significant contribution to the flux of nitrate to nitrite in the environment.

Moraxella caprae sp. nov., a new member of the classical Moraxellae with very close affinity to Moraxella bovis

Eight phenotypically homogeneous Moraxella-like strains were isolated from the nasal flora of healthy goats. Total genomic DNA-DNA hybridization, DNA base composition determination, and genetic transformation studies were performed to determine the relationships of these bacteria to the classical moraxellae. The eight new isolates exhibited very high levels of genetic affinity to Moraxella bovis, as shown by quantitative and qualitative genetic transformation data, and exhibited high DNA-DNA relative binding ratios to each other (63% or more) but lower levels of DNA homology with all of the other species investigated, including the closely related classical moraxellae. Our results, combined with the general morphologic and phenotypic profiles of these organisms, indicate that they should be classified with the classical moraxellae, and we propose the name Moraxella caprae for them. Strain 8897 (= CCUG 33296 [corrected] = NCTC 12877) is the type strain of M. caprae.

Plasmid-mediated degradation of hydroxylated, methoxylated, and carboxylated benzene derivatives in Moraxella sp

Chemical industries produce wastewater that contains large amount of aromatic substances including chlorinated compounds. Moraxella sp. isolated from a petroleum refinery unit efficiently used a variety of benzene derivatives bearing hydroxyl, methoxyl, carboxyl, and chloro- groups as the sole carbon source. The isolate harbored two plasmids of high mobility that are responsible for the utilization of these substrates.

Comparison of three rapid methods, tributyrine, 4-methylumbelliferyl butyrate, and indoxyl acetate, for rapid identification of Moraxella catarrhalis

Moraxella catarrhalis can easily be differentiated from other oxidase-positive, gram-negative cocci with tributyrine, 4-methylumbelliferyl butyrate, or indoxyl acetate. All M. catarrhalis give positive reactions, and all Neisseria spp. give negative reactions. The 4-methylumbelliferyl butyrate tube test and indoxyl acetate strip test provide same-day identification of M. catarrhalis isolates.

Some cultural characteristics of Branhamella ovis isolated from the conjunctival sac of sheep

The colonial morphology and other cultural characteristics of Branhamella ovis were studied. The current investigation showed that colonies could be designated R (rough) and S (smooth) dependent on their appearance on agar. The colonial variants were apparently stable and each produced distinct types of pitting when grown on agar. A CAMP-like reaction was also shown to be a characteristic of B. ovis.

A polysaccharide produced by a mucoid strain of Moraxella nonliquefaciens with a 2-acetamido-2-deoxy-5-O-(3-deoxy-beta-D-manno-octulopyranosyl)-beta-D- galactopyranosyl repeating unit

A capsular polysaccharide, isolated from the mucoid Moraxella nonliquefaciens strain 3828/60, has been investigated by component analyses, periodate oxidation, methylation analyses, mass spectrometry, 1H and 13C NMR spectroscopy, and hydrolysis to give a disaccharide that was isolated and characterised. The results showed that the polysaccharide has the repeating unit-->3)-beta-D- GalpNAc-(1-->5)-beta-Kdo p-(2-->, with approximately 40% of O-8 of Kdo being acetylated.

Bacterial metabolism of 5-aminosalicylic acid. Initial ring cleavage

The metabolism of 5-aminosalicylate (5AS) by a bacterial strain, Pseudomonas sp. BN9, was studied. Intact cells of Pseudomonas sp. BN9 grown with 5AS oxidized 5AS and 2,5-dihydroxybenzoate (gentisate), whereas cells grown with gentisate oxidized only the growth substrate of all substituted salicylates tested. Cell extracts from Pseudomonas sp. BN9 catalysed the stoichiometric reaction of 1 mol of oxygen with 1 mol of 5AS to a metabolite with an intense u.v.-absorption maximum at 352 nm (pH 8.0). This metabolite was accumulated under neutral conditions, but was rapidly destroyed at acid pH. It was identified by m.s. and acid-catalysed deamination to fumarylpyruvate (trans-2,4-dioxohept-5-enedioic acid) as cis-4-amino-6-carboxy-2-oxohexa-3,5-dienoate, thus demonstrating direct cleavage of the monohydroxylated substrate 5AS to a non-aromatic ring-fission product. The enzyme responsible for conversion of 5AS was shown to be Fe(II)-dependent and to be distinct from gentisate 1,2-dioxygenase in strain BN9.

Propachlor degradation by a soil bacterial community

Soil from a pesticide disposal site was used to enrich for microorganisms that degraded the acylanilide herbicide propachlor (2-chloro-N-isopropylacetanilide). After seven transfers of the enrichment, the culture contained about six strains. The highest yield of microbial biomass occurred if just two of these isolates, strains DAK3 and MAB2, were inoculated into a mineral salts medium containing propachlor. When only strain DAK3 was grown on propachlor, a metabolite (2-chloro-N-isopropylacetamide) was released into the medium. Strain MAB2 could grow on this metabolite. The results of morphological and physiological tests suggest that strains DAK3 and MAB2 most closely resemble species belonging to the genera Moraxella and Xanthobacter, respectively. Strain DAK3 can respire and grow on N-substituted acylanilides containing methyl, ethyl, or isopropyl substitutions, but is incapable of respiration or growth on acetanilide, aniline, or the acylanilide herbicides alachlor and metolachlor. Strain DAK3 appears to use the aromatic C atoms of propachlor for growth, as suggested by the growth yield on propachlor and the induction of catechol 2,3-oxygenase activity in acylanilide-grown cells.

Preliminary study on relationships among strains forming a bacterial community selected on naphthalene from a marine sediment

Two bacterial strains were isolated from a bacterial community formed of nine strains, selected from a marine sediment on a seawater medium with naphthalene as sole carbon source. The two strains studied in the present work were the only strains of this community able to grow in pure culture on naphthalene; therefore, they were called "primary" strains. The seven other strains were maintained in the community by using metabolic intermediates of the two primary strains; they were called "auxiliary" strains. Regulation of naphthalene metabolism was studied for the two primary strains. They oxidized naphthalene into catechol, which was degraded only by the meta pathway. For Pseudomonas Lav. 4, naphthalene oxygenase and salicylate hydroxylase were inducible; catechol 2,3-dioxygenase was constitutive. For Moraxella Lav. 7, naphthalene oxygenase was constitutive; salicylate hydroxylase and catechol 2,3-oxygenase were inducible. The Moraxella strain carries two cryptic plasmids, about 63- and 85-kb in molecular size. In the bacterial community culture medium, Moraxella Lav. 7 prevented accumulation of 2-hydroxymuconate semialdehyde formed by Pseudomonas Lav. 4. The auxiliary strains take up formic, acetic, pyruvic, propionic, and succinic acids released by the two primary strains.

Comparative characterization of the leukocidic and hemolytic activity of Moraxella bovis

The cytotoxic effect of Moraxella bovis 118F on bovine neutrophils was evaluated and characterized by use of a 51Cr release assay. Neutrophils harvested from healthy adult cattle were labeled with 51Cr. The leukocidic activity produced by M bovis 118F, a hemolytic strain of M bovis, was heat-labile. A live culture of strain 118F, at a ratio of 100 bacteria/neutrophil, released 97.7% of the 51Cr from labeled neutrophils. Neither a heat-killed preparation of M bovis 118F nor a live or heat-killed preparation of M bovis IBH63 (a nonhemolytic and nonpathogenic strain) induced significant (P greater than 0.05) release of 51Cr. Moraxella bovis 118F broth culture filtrates prepared for evaluation of leukocidic activity also were evaluated for hemolytic activity. These 2 toxic activities had several characteristics in common. Both were filterable, heat-labile, produced by a hemolytic strain, and were released during early logarithmic phase growth from broth cultures. Leukocidic and hemolytic activities were protected from degradation by phenylmethyl sulfonyl fluoride, a serine protease inhibitor. Leukocidic and hemolytic activities were dependent on calcium ions. Filtrate resulted in 54.1% 51Cr release from labeled neutrophils and contained 646.7 hemolytic U/ml, respectively, when saline (0.85% NaCl) + 10 mM CaCl2 solution was used as diluent. Neither saline solution nor saline + 10 mM MgCl2 solution supported leukocidic or hemolytic activity. Serum, obtained from several calves 10 to 38 days after M bovis inoculation, substantially neutralized leukocidic and hemolytic activities, compared with paired preinoculation serum samples.(ABSTRACT TRUNCATED AT 250 WORDS)

Differentiation of some gram-negative glucose nonfermenting bacteria using miniaturized carbon sources assimilation tests

In water and soil the gram-negative nonfermenting bacteria play an important role in the biological mineralization process. To improve the methods for species differentiation of these heterogenous bacterial group, a total of 481 reference strains of gram-negative glucose nonfermenting bacteria belonging to the genera Pseudomonas, Alcaligenes, Bordetella, Agrobacterium, Moraxella, Acinetobacter, Flavobacterium and some CDC groups have been investigated for their ability to utilize 42 different carbon substrates with the help of a standardized and automated micromethod. Most species showed a typical pattern of carbon utilization and hence could be differentiated from each other within their genera. As already has been demonstrated by more clinical significant Pseudomonas species, this method proves to be a useful alternative to existing methods of differentiation, especially with representatives of the families Pseudomonadaceae and Alcaligenaceae.

Degradation of naphthalene-2,6- and naphthalene-1,6-disulfonic acid by a Moraxella sp

A naphthalene-2,6-disulfonic acid (2,6NDS)-degrading Moraxella strain was isolated from an industrial sewage plant. This culture could also be adapted to naphthalene-1,6-disulfonic acid as growth substrate. Regioselective 1,2-dioxygenation effected desulfonation and catabolism to 5-sulfosalicylic acid (5SS), which also could be used as the sole carbon source. 5SS-grown cells exhibited high gentisate 1,2-dioxygenase activity. Neither 5SS- nor gentisate-grown cells oxidized 2,6NDS; therefore, 2,6NDS or an early metabolite must serve as an inducer of the initial catabolic enzyme(s).

A note on hydrolysis of tributyrin by Branhamella and Neisseria

Sixty-three strains of Branhamella and Neisseria were tested by two methods for their ability to hydrolyse glycerol tributyrate. After the conventional plate test, gas liquid chromatographical (GLC) analysis of the agar medium was carried out to detect the hydrolysis product, butyric acid, and other volatile fatty acids. All strains of Branhamella catarrhalis, Neisseria caviae, N. cuniculi and N. ovis but no other Neisseria spp. gave positive results with the conventional test. With GLC, however, most strains of Branhamella and Neisseria were shown to liberate butyric acid. In addition, some strains liberated acetic and isovaleric acids. Greater amounts of butyric acid were produced by clinical strains, in particular B. catarrhalis, compared with reference strains. It was concluded that the conventional plate test for tributyrin hydrolysis differentiates B. catarrhalis, N. caviae, N. cuniculi and N. ovis from other Neisseria.

Supplement peptone agar--a simple carbohydrate degradation plate medium for the identification of Neisseria species

A carbohydrate degradation medium was developed for the detection of acid production by Neisseria species and Branhamella catarrhalis. A total of 223 clinical isolates were identified by Supplemented Peptone Agar and the results were compared with those of Cystine Trypticase Agar. Supplemented Peptone Agar and Cystine Trypticase Agar correctly identified 99.1% and 93.7% of the total strains respectively within 24 h. With Cystine Trypticase Agar method another 4% of the isolates could be identified but required an additional 24 h of incubation.

Role of dissolution rate and solubility in biodegradation of aromatic compounds

Strains of Moraxella sp., Pseudomonas sp., and Flavobacterium sp. able to grow on biphenyl were isolated from sewage. The bacteria produced 2.3 to 4.5 g of protein per mol of biphenyl carbon, and similar protein yields were obtained when the isolates were grown on succinate. Mineralization of biphenyl was exponential during the phase of exponential growth of Moraxella sp. and Pseudomonas sp. In biphenyl-supplemented media, Flavobacterium sp. had one exponential phase of growth apparently at the expense of contaminating dissolved carbon in the solution and a second exponential phase during which it mineralized the hydrocarbon. Phase-contrast microscopy did not show significant numbers of cells of these three species on the surface of the solid substrate as it underwent decomposition. Pseudomonas sp. did not form products that affected the solubility of biphenyl, although its excretions did increase the dissolution rate. It was calculated that Pseudomonas sp. consumed 29 nmol of biphenyl per ml in the 1 h after the end of the exponential phase of growth, but 32 nmol of substrate per ml went into solution in that period when the growth rate had declined. In a medium with anthracene as the sole added carbon source, Flavobacterium sp. converted 90% of the substrate to water-soluble products, and a slow mineralization was detected when the cell numbers were not increasing. Flavobacterium sp. and Beijerinckia sp. initially grew exponentially and then arithmetically in media with phenanthrene as the sole carbon source. Calculations based on the growth rates of these bacteria and the rates of dissolution of phenanthrene suggest that the dissolution rate of the hydrocarbon may limit the rate of its biodegradation.

Infectious bovine keratoconjunctivitis: seasonal variation in cultural, biochemical and immunoreactive properties of Moraxella bovis isolated from the eyes of cattle

The eyes of 20 young cattle were examined over an 18 month period in which 12 members of the group contracted infectious bovine keratoconjunctivitis (IBK). On each of 23 occasions cultural, biochemical and immunoreactive properties of up to 6 isolates of Moraxella bovis derived from each eye were determined. Relationships between the clinical response of eyes, phenotypic properties of M. bovis and annual variations in the level of solar ultraviolet radiation of 280 to 320 nm wavelength were examined. M. bovis was isolated from all IBK-affected and some unaffected eyes less than one month after the maximum annual level of the mean weekly UV radiation (2,840 mWh.m-2 X nm-1) was recorded. A high proportion of M. bovis from IBK lesions were simultaneously active in haemolysis, agar corrosion, gelatin liquefaction and litmus milk peptonisation. Some of these characteristics showed marked dissociation despite consistent reactivity in the fluorescent antibody test, which had a sensitivity and specificity of 95%. Fall in the mean weekly level of UV radiation below 1,438 mWh X m-2 X nm-1 in autumn was accompanied by healing of ulcers, persistent scar formation and a decline in the number of M. bovis isolated from affected eyes. A slower decline in the number of M. bovis isolated from apparently healthy eyes occurred in the winter and occasional fresh IBK lesions occurred.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of Rapid NFT system and conventional methods for identification of nonsaccharolytic gram-negative bacteria

This study examined the Rapid NFT system (Analytab Products, Plainview, N.Y.) to determine its ability to accurately identify 229 clinical isolates of mostly nonsaccharolytic gram-negative rods. Identifications were classified by the following scheme: correct (corresponding to excellent, very good, good, or acceptable identification as listed in the code book); low discrimination (correct identification among a range of listed possibilities, with additional tests necessary for accurate identification); incorrect. Correct identification was considered correct to species and subspecies for all organisms except Alcaligenes faecalis and "Alcaligenes odorans"; "A. faecalis/odorans" was considered a correct response. By using these criteria, 71.6% of the strains were correctly identified, 17.9% were identified with low discrimination, and 10.5% were incorrectly identified. When consideration was made for incorrect identification resulting from taxonomic problems (e.g., Alcaligenes and Moraxella spp.), incorrect identifications fell to 5.2%. The Rapid NFT system was truly rapid and was easy to use and interpret. Its use of carbon substrate assimilation enables it to provide more accurate identification of medically important nonsaccharolytic bacteria than do other commercially available systems.

Defined medium for Moraxella (Branhamella) catarrhalis

A defined medium for growth of 24 strains of Moraxella (Branhamella) catarrhalis was devised. This medium (medium B4) contains sodium lactate as a partial carbon source, proline as both a partial carbon source and a partial nitrogen source, aspartate as a partial nitrogen source, and the growth factors arginine, glycine, and methionine. Either aspartate, glutamate, or proline could serve as sole nitrogen source, but growth occurred at a significantly better rate if proline was present together with either aspartate or glutamate, or with both aspartate and glutamate. With the exception of strain ATCC 23246, all the strains had an absolute requirement for arginine and either a partial or absolute requirement for glycine. The concentration of glycine required for optimal growth was found to be relatively high for an amino acid growth factor. Heart infusion broth was found to be growth inhibitory for spontaneous mutants of one strain able to grow in the absence of arginine, and such mutants reverted readily to arginine dependence accompanied by the ability to grow faster on the complex medium. Growth rates in the defined medium B4 were enhanced by the simultaneous addition of asparagine, glutamate, glutamine, leucine, lysine, histidine, and phenylalanine.

Microbial mineralization of ring-substituted anilines through an ortho-cleavage pathway

Moraxella sp. strain G is able to utilize as sole source of carbon and nitrogen aniline, 4-fluoroaniline, 2-chloroaniline, 3-chloroaniline, 4-chloroaniline (PCA), and 4-bromoaniline but not 4-iodoaniline, 4-methylaniline, 4-methoxyaniline, or 3,4-dichloroaniline. The generation time on PCA was 6 h. The pathway for the degradation of PCA was investigated by analysis of catabolic intermediates and enzyme activities. Mutants of strain G were isolated to enhance the accumulation of specific pathway intermediates. PCA was converted by an aniline oxygenase to 4-chlorocatechol, which in turn was degraded via a modified ortho-cleavage pathway. Synthesis of the aniline oxygenase was inducible by various anilines. This enzyme exhibited a broad substrate specificity. Its specific activity towards substituted anilines seemed to be correlated more with the size than with the electron-withdrawing effect of the substituent and was very low towards anilines having substituents larger than iodine or a methyl group. The initial enzyme of the modified ortho-cleavage pathway, catechol 1,2-dioxygenase, had similar characteristics to those of corresponding enzymes of pathways for the degradation of chlorobenzoic acid and chlorophenol, that is, a broad substrate specificity and high activity towards chlorinated and methylated catechols.

Moraxella bovis hemolysin

Moraxella bovis hemolysin was readily filterable through polycarbonate membrane filters, but not through nitrocellulose filters. The hemolysin was filterable through polycarbonate filters with pore diameters of greater than or equal to 0.015 micron (APD). Of the hemolytic activity of cell-free filtrates, 74% could be pelleted by ultracentrifugation at 100,000 X g for 2 1/2 hours. Hemolytic activity could be demonstrated in preparations of outer membrane fragments isolated from log-phase cultures. Hemolysin in M bovis broth cultures reached a maximum concentration in late logarithmic phase (4.5 hours after inoculation) and declined thereafter. Hemolysin was inactivated by heat, trypsin, formalin, and lyophilization.

Novel transformations of i-cholesterol and 6 beta-methoxy-i-cholesterol by Moraxella sp

A soil microorganism was isolated by the enrichment culture technique using cholesterol as the sole source of carbon. The organism has been identified as belonging to the genus Moraxella. With this organism two novel biotransformations of sterols were observed viz. (1) isomerization of 3 alpha,5 alpha-cyclocholestan-6 beta-ol (i-cholesterol) to cholesterol, (2) demethylation of 6 beta-methoxy-3 alpha,5 alpha-cyclocholestane (6 beta-methoxy-i-cholesterol) to i-cholesterol with subsequent isomerization to cholesterol. The enzymes responsible for these transformations were shown to be inducible. The pH optimum of the partially purified i-cholesterol isomerase was found to be 8.4. The apparent Km value for i-cholesterol was 1.43 microM. A plausible mechanism for the i-cholesterol isomerization has been discussed.

The bacterial biogenesis of isobutyraldoxime O-methyl ether, a novel volatile secondary metabolite

Production of the volatile metabolite, isobutyraldoxime O-methyl ether (IBME) by a Moraxella-like organism NCIB 11650 was investigated under a variety of environmental conditions using gas chromatography. Under aerobic conditions up to 10 micrograms IBME ml-1 was produced on mineral salts media containing 0.5% (w/v) glucose or succinate as sole C source with 0.1% (w/v) NH4Cl as sole N source. Exogenous L-valine further stimulated IBME formation up to 25 micrograms ml-1 but supplementation of the medium with D-isomer or other amino acids had little effect on IBME production and did not lead to the appearance of analogues of IBME. Trapping experiments using [14C]valine confirmed that IBME was derived from this amino acid. Several other bacterial species examined, e.g. Alcaligenes sp. NCIB 11652, another Moraxella-like organism NCIB 11651 and Pseudomonas sp. NCIB 11653 also produced IBME under similar conditions. The Alcaligenes strain synthesized up to 20 micrograms ml-1 in the absence of valine and up to 90 micrograms ml-1 in its presence. The product of IBME exhibited many features characteristic of the formation of a secondary metabolite. Thus biosynthesis was confined to a narrower range of temperature than cell division, was almost completely suppressed by 300 mM-phosphate and was inhibited by high concentrations of readily utilizable C sources. Although IBME synthesis in the Moraxella-like organism NCIB 11650 appeared to be growth-related, its formation by both the Alcaligenes sp. and the Moraxella-like organism NCIB 11651 was delayed until the late-exponential and early-stationary phases of growth. The biological significance of this novel class of secondary metabolite is discussed and a possible biosynthetic route proposed.

Coliform inhibition by bacteriocin-like substances in drinking water distribution systems

Bacterial isolates from an unchlorinated potable groundwater system and a chlorinated surface water system were screened by an agar overlay method for the ability to produce bacteriocin-like substances (BLS) inhibitory to the growth of Escherichia coli, Klebsiella sp., and Enterobacter aerogenes. The production of coliform-specific BLS by noncoliform bacteria varied with the site and date of isolation as well as the genus of the producer strain. A total of 448 bacterial isolates were screened from the chlorinated system, and 22.1% produced BLS specific for at least one of the three coliforms. In the unchlorinated system, 7.9% (n = 696) possessed this ability. Flavobacterium/Moraxella comprised 57.1% of all bacteria (from both systems) producing BLS. The possibility that BLS interfere with coliform detection in standard bacteriological water quality tests is discussed.

Identification of isobutyronitrile and isobutyraldoxime O-methyl ether as volatile microbial catabolites of valine

G.l.c.--mass-spectral analysis of headspace above cultures of Aeromonas and Moraxella spp. indicates the presence of isobutyronitrile, isobutyraldoxime O-methyl ether, methacrylonitrile and possibly methacrylaldoxime O-methyl ether. Accumulation of these catabolites is maximal under low oxygen concentrations and is enhanced by enrichment of the medium with valine. Isobutyraldoxime O-methyl ether is established as the compound observed but not identified in previous studies with other bacterial species involved in spoilage of meat and chicken.

The identification of Moraxella bovis and Neisseria ovis from the eyes of cattle and sheep

The cultural characteristics of Moraxella bovis and Neisseria ovis from eyes of cattle and sheep were examined to determine which tests precisely identified the isolates. The elongation test to distinguish the bacillary M vovis from the coccal N ovis, the nitrate reduction and the litmus milk tests were found to be the most reliable.

High-resolution gas chromatographic profiles of volatile organic compounds produced by microorganisms at refrigerated temperatures

Three different strains of bacteria isolated from spoiled, uncooked chicken were grown in pure culture on Trypticase soy agar supplemented with yeast extract. The volatile organic compounds produced by each culture were concentrated on a porous polymer precolumn and analyzed by high-resolution gas chromatographic mass spectrometry. Twenty different compounds were identified. Both qualitative and quantitative differences in the chromatographic profiles from each culture were found.

Production and characterization of Moraxella bovis hemolysin

Moraxella bovis hemolysin was produced in trypticase soy broth and maximum hemolytic activity of the culture was observed during the logarithmic phase of growth. The hemolysin was filterable through a 0.22-micrometer (APD) membrane filter, heat labile, and destroyed by treatment with formalin or trypsin. There was no difference in the amount of hemolysin production by rough or smooth colony types of an isolate, although differences were observed between 2 different isolates. Partial requirement of a sulfhydryl group and divalent cations were suggestive of an enzymatic nature of M bovis hemolysin.