Constitutive NADP-dependent alcohol dehydrogenase ofAcinetobacter sp. strain HO1-N

An NADP-dependent alcohol dehydrogenase was purified to homogeneity fromAcinetobacter sp. strain HO1-N. The enzyme appears to be a tetramer of sub-unit M_r 40,600, and it has kinetic and other properties almost identical to those of an enzyme previously isolated fromAcinetobacter calcoaceticus strain NCIB 8250. The alcohol dehydrogenases from both of these strains ofAcinetobacter oxidized primary alcohols. The highestk _cat(app) values were with alcohols containing from four to eight carbon atoms; there was activity up to tetradecan-l-ol, although it was a poor substrate, but there was not measurable activity with hexadecan-l-ol. The highest specificity constant was found with hexan-l-ol as substrate when the messurements were made in the absence of dioxan, and with decan-l-ol as substrate when assayed in the presence of dioxan. It seems unlikely that this enzyme is involved in the metabolism of wax esters or of long-chain alkanes.     

Influence of growth phase and carbon source on the content of rubredoxin in Acinetobacter calcoaceticus

The rubredoxin content of Acinetobacter calcoaceticus in dependence on the carbon source (acetate, n-alkanes, succinate, L-malate) and on the growth phase was studied by means of a radioimmunoassay. The method used was specific for rubredoxin from Acinetobacter calcoaceticus. The formation of rubredoxin increased with time up to the end of the logarithmic phase when n-alkanes were the sole carbon source. After growth of Acinetobacter calcoaceticus on non-hydrocarbon substrates, rubredoxin was not detected.     

Glucose stimulates a decrease of the fatty acid saturation degree in Acinetobacter calcoaceticus

The fatty acid composition of Acinetobacter calcoaceticus 69-V was determined under various growth conditions. Saturated, unsaturated, and hydroxy fatty acids with chain lengths of 12–18 carbon atoms predominated in the fatty acid profile. With acetate or propanol as growth substrates, the ratio of saturated to unsaturated fatty acids varied with changes in the temperature. This was the only adaptive mechanism detected that compensated for the physical effects of temperature alterations on the cell membranes. The fatty acid composition of A. calcoaceticus grown at 40 °C had a saturation degree of approximately 50%; after growth at 20 °C it was approximately 35%. In the presence of a carbon and energy source, A. calcoaceticus was able to respond to temperature reductions under oxic conditions regardless of whether fatty acid biosynthesis was inhibited or not. This suggests an aerobic mechanism of fatty acid biosynthesis and the involvement of a fatty acid desaturase system. Addition of the non-growth substrate, glucose, helped the organism to adapt to lower temperature. The molecular mechanism of the aid is not really understood. The oxidation of glucose could provide the desaturase either with electrons directly via a pyrrolo-quinoline-quinone-linked glucose dehydrogenase or with NADH after fatty acid degradation has been initiated by ATP generated by the oxidation of glucose. Received: 19 June 1998 / Accepted: 28 December 1998     

Evaluation of a mixed bacterial culture for de-emulsification of water-in-petroleum oil emulsions

A mixed bacterial culture, isolated from a petroleum-contaminated site, was evaluated for its de-emulsification capabilities using a kerosene–water model emulsion system and petroleum oilfield emulsion. The culture exhibited high de-emulsification activity with 96% de-emulsification of a water-in-oil emulsion within 24 h. Nine morphologically distinct pure colonies were isolated from the mixed culture and identified and their de-emulsification capabilities were tested. All three strains of Acinetobacter, i.e. A. calcoaceticus, A. calcoaceticus BV ALC and A. radioresistans were capable of providing > 90% de-emulsification, while Pseudomonas aeruginosa, P. carboxydohydrogena, and Alcaligenes latus showed > 80% de-emulsification. Different de-emulsification patterns were observed between species of Acinetobacter and Pseudomonas. The mixed culture exhibited higher de-emulsifier activity, as compared to the most effective pure culture, Acinetobacter calcoaceticus, when de-emulsification ability was tested on an oilfield water-in-oil emulsion.     

Outer membrane vesiculation of acinetobacter calcoaceticus

For intact cells of A. calcoaceticus 69V susceptibility to hydrophobic agents (antibiotics, dyes) was established. The composition of its outer membrane and comparison with that of a reference strain, A. calcoaceticus CCM 5593 with a blocked hydrophobic pathway, gave no indication of phospholipid bilayer domains as the structural basis of these permeability characteristics. The outer membrane composition together with the data of time-resolved fluorescence anisotropy measurements is indicative of a high state of order of the hydrocarbon region. A. calcoaceticus 69V releases lipopolysaccharide (LPS)-rich membrane vesicles into the growth medium when grown on a hydrophobic carbon source. While the cells contain both R-form and S-form LPS, the LPS released with the vesicles is exclusively of the R-type. The same selectivity with respect to LPS composition was observed when LPS was removed from intact cells by EDTA-NaCl treatment which leads to a break-down of the barrier to hydrophobic agents in A. calcoaceticus CCM 5593. We propose that due to its physical properties, R-form LPS forms tightly packed structures within the membrane which, under certain conditions, become destabilized and liberated into the surrounding medium. As a consequence, a disturbance of the highly ordered lateral molecular arrangement might lead to altered permeability properties of the outer membrane as suggested in one of the two alternative models existing to explain permeability changes observed in deep rough mutant strains of Enterobacteriaceae.     

Phylogenetic study of sponge associated bacteria from the Lakshadweep archipelago and the antimicrobial activities of their secondary metabolites

Marine ecosystem of the Lakshadweep archipelago is unique and known to have a very high degree of biodiversity with a number of endemic flora and fauna. The present study focuses to isolate the endosymbiotic microorganism from sponges and its effectiveness against marine ornamental fish pathogens. The sponges were collected from Agatti island of Lakshadweep archipelago and identified as Clathria procera, Sigmadocia fibulata and Dysidea granulosa. In which, 15 different types of bacteria were isolated and screened against marine ornamental fish pathogens (A. hydrophila, Vibrio alginolyticus, V. harveyii, V. parahaemolyticus and Pseudomonas fluorescens). The strain S25 was found as potential bacteria based on their antimicrobial activity against the fish pathogens. Molecular identification of the potential strain (S25) of the 16S rRNA gene showed 99% identity with Acinetobacter sp. The sequenced 16 s rRNA gene with 1,081 bp in length was submitted in NCBI Genbank and Accession was obtained (GenBank Accession number HM004071). The strain exhibited high similarity (99%) with the 16S rRNA gene of Acinetobacter calcoaceticus from GenBank database. Crude extract obtained with acetone and ethyl acetate from extracellular products of S25 showed significant antimicrobial activity by disc diffusion assay using 1,500 μg/ml of crude extract. Extracellular metobolite of A. calcoaceticus was extracted by shake flask method and the crude extract was partially purified by thin layer chromatography. Partially purified crude extract showed significant inhibition zone of antimicrobial activity (A. hydrophila, V. alginolyticus, V. parahaemolyticus) and less similar activity against V. harveyii and P. fluorescens. This is the first report on A. calcoaceticus isolated from sponges of Lakshadweep archipelago and the studies are underway to characterize and purify the antimicrobial compounds of the potential bacteria.     

Initial steps of sophoroselipid biosynthesis by Candida bombicola ATCC 22214 grown on glucose

 Candida bombicola ATCC 22214 produces the glycolipid sophoroselipid when cultivated on a medium with glucose as the sole carbon source. Under phosphate-limiting conditions the product yield rises from 0.033 to 0.143 and the specific product formation rate rises from 0.004 h^-1 to 0.007 h^-1. Enhanced sophoroselipid synthesis is initiated by the decline of the specific activities of NAD- and NADP-dependent isocitrate dehydrogenase (EC 1.1.1.41 and 1.1.1.42) to 2% and 0% of the initial activities respectively. Constantly high specific activity of citrate synthase (EC 4.1.3.7) causes an accumulation of isocitrate and citrate in the mitochondria. Both acids are transported into the cytosol where citrate is cleaved by ATP: citrate lyase (EC 4.1.3.8) giving rise to acetyl-CoA, the precursor of fatty acid synthesis. The ATP: citrate lyase is unaffected by different energy charges; the apparent K _m values for coenzyme A, ATP and citrate are 23 μM, 250 μM and 256 μM respectively. NADPH for fatty acid synthesis might be generated by further metabolism of oxaloacetate, the other product of the citrate-cleaving reaction, by oxidation of the isocitrate by the cytosolic NADP-dependent isocitrate dehydrogenase or via the hexose monophosphate shunt. A possible explanation for sophoroselipid formation during exponential growth is given. Received: 7 November 1995/Received revision: 19 March 1996/Accepted: 25 March 1996     

Extracellular location of a β-lactamase produced by Acinetobacter calcoaceticus

Summary Acinetobacter calcoaceticus strains 69 V and CCM 5593 formed a -lactamase that was predominantly found extracellularly in the culture medium. The enzyme has the characteristics of an inducible chromosomally mediated cephalosporinase. Neither cell lysis nor periplasmic leakage are responsible for the extracellular location. The mechanism of secretion is not known.Offprint requests to: P. Borneleit     

Characterization of the extracellular lipase, LipA, of Acinetobacter calcoaceticus BD413 and sequence analysis of the cloned structural gene

The extracellular lipase from Acinetobacter calcoaceticus BD413 was purified to homogeneity, via hydrophobic-interaction fast performance liquid chromatography (FPLC), from cultures grown in mineral medium with hexadecane as the sole carbon source. The enzyme has an apparent molecular mass of 32 kDa on SDS-polyacrylamide gels and hydrolyses long acyl chain p-nitrophenol (pNP) esters, like pNP palmitate (pNPP), with optimal activity between pH 7.8 and 8.8. Additionally, the enzyme shows activity towards triglycerides such as olive oil and tributyrin and towards egg-yolk emulsions. The N-terminal amino acid sequence of the mature protein was determined, and via reverse genetics the structural lipase gene was cloned from a gene library of A. calcoaceticus DNA in Escherichia coli phage M13. Sequence analysis of a 2.1 kb chromosomal DNA fragment revealed one complete open reading frame, lipA, encoding a mature protein with a predicted molecular mass of 32.1 kDa. This protein shows high similarity to known lipases, especially Pseudomonas lipases, that are exported in a two-step secretion mechanism and require a lipase-specific chaperone. The identification of an export signai sequence at the N-terminus of the mature lipase suggests that the lipase of Acinetobacter is also exported via a two-step translocation mechanism. However, no chaperone-encoding gene was found downstream of lipA, unlike the situation in Pseudomonas. Analysis of an A. calcoaceticus mutant showing reduced lipase production revealed that a periplasmic disutphide oxidoreductase is involved in processing of the lipase. Via sequence alignments, based upon the crystal structure of the closely related Pseudomonas glumae lipase, a model has been made of the secondary-structure elements in AcLipA. The active site serine of AcLipA was changed to an alanine, via site-directed mutagenesis, resulting in production of an inactive extracellular lipase.     

Combination of ARDRA and RAPD genotyping techniques in identification of Acinetobacter spp. genomic species

A total of 10 non-repetitive multi-drug-resistant Acinetobacter strains were collected. With reference to A. calcoaceticus (ATCC23055), A. baumannii (ATCC19606), A. lwoffii (ATCC17986), and A. junii (NCTC5866),DNA fingerprint technique, amplified ribosomal DNA restriction analysis (ARDRA), and random amplified polymorphism DNA (RAPD) were carried out to identify the genomic species of Acinetobacter spp. The distances between them were calculated by the unweighted pair group method with arithmetic (UPGMA). Genotypes of Acinetobacter spp. were effectively classified and an A. junii together with nine A. baumannii isolates was genomically identified. The combination of ARDRA and RAPD DNA-fingerprint technique shows high complementarity, and could be a useful tool in Acinetobacter genomic species identification. __________ Translated from Microbiology, 2007, 34(2): 303–306 [译自:微生物学通报]     

Peculiarities of Ethanol Metabolism in an Acinetobacter sp. Mutant Strain Defective in Exopolysaccharide Synthesis

Activities of the key enzymes of ethanol metabolism were assayed in ethanol-grown cells of an Acinetobacter sp. mutant strain unable to synthesize exopolysaccharides (EPS). The original EPS-producing strain could not be used for enzyme analysis because its cells could not to be separated from the extremely viscous EPS with a high molecular weight. In Acinetobacter sp., ethanol oxidation to acetaldehyde proved to be catalyzed by the NAD⁺-dependent alcohol dehydrogenase (EC 1.1.1.1.). Both NAD⁺ and NADP⁺ could be electron accepters in the acetaldehyde dehydrogenase reaction. Acetate is implicated in the Acinetobacter sp. metabolism via the reaction catalyzed by acetyl-CoA-synthetase (EC 6.2.1.1.). Isocitrate lyase (EC 4.1.3.1.) activity was also detected, indicating that the glyoxylate cycle is the anaplerotic mechanism that replenishes the pool of C₄-dicarboxylic acids in Acinetobacter sp. cells. In ethanol metabolism by Acinetobacter sp., the reactions involving acetate are the bottleneck, as evidenced by the inhibitory effect of sodium ions on both acetate oxidation in the intact cells and on acetyl-CoA-synthetase activity in the cell-free extracts, as well as by the limitation of the C₂-metabolism by coenzyme A. The results obtained may be helpful in developing a new biotechnological procedure for obtaining ethanol-derived exopolysaccharide ethapolan.     

Evolutionary implications of features of aromatic amino acid biosynthesis in the genus Acinetobacter

Key enzymes of aromatic amino acid biosynthesis were examined in the genus Acinetobacter. Members of this genus belong to a suprafamilial assemblage of Gram-negative bacteria (denoted Superfamily B) for which a phylogenetic tree based upon oligonucleotide cataloging of 16S rRNA exists. Since the Acinetobacter lineage diverged at an early evolutionary time from other lineages within Superfamily B, an examination of aromatic biosynthesis in members of this genus has supplied improtant clues for the deduction of major evolutionary events leading to the contemporary aromatic pathways that now exist within Superfamily B. Together with Escherichia coli, Pseudomonas aeruginosa and Xanthomonas campestris, four well-spaced lineages have now been studied in comprehensive detail with respect to comparative enzymological features of aromatic amino acid biosynthesis. A. calcoaceticus and A. lwoffii both possess two chorismate mutase isozymes: one a monofunctional isozyme (chorismate mutase-F), and the other (chorismate mutase-P) a component of a bifunctional P-protein (chorismate mutase-prephenate dehydratase). While both P-protein activities were feedback inhibited by l-phenylalanine, the chorismate mutase-P activity was additionally inhibited by prephenate. Likewise, chorismate mutase-F was product inhibited by prephenate. Two isozymes of 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase were detected. The major isozyme (>95%) was sensitive to feedback inhibition by l-tyrosine, whereas the minor isozyme was apparently insensitive to allosteric control. Prephenate dehydrogenase and arogenate dehydrogenase activities were both detected, but could not be chromatographically resolved. Available evidence favors the existence of a single dehydrogenase enzyme, exhibiting substrate ambiguity for prephenate andl-arogenate. Dehydrogenase activity with either of the latter substrates was specific for NADP⁺, NAD⁺ being ineffective. Consideration of the phylogeny of Superfamily-B organisms suggests that the stem ancestor of the Superfamily possessed a single dehydrogenase enzyme having ambiguity for both substrate and pyridine nucleotide cofactor. Since all other members of Superfamily B have NAD⁺-specific dehydrogenases, specialization for NADP⁺ must have occurred following the point of Acinetobacter divergence, leading to the dichotomy seen in present-day Superfamily-B organisms.     

Fatty acid patterns of Acinetobacter calcoaceticus 69-V indicate sensitivity against xenobiotics

The growth of Acinetobacter calcoaceticus 69-V on the alcohols ethanol, n-propanol, n-pentanol, n-hexanol and on phenol caused an alteration in its fatty acid composition leading to a gradual increase in the degree of saturation of the C16 acids from 55.4% to 83.5%, which (apart from phenol-grown cells) correlated to an increase in the resistance of the electron-transport phosphorylation against the effect of 2,4-dinitrophenol. These changes are in principle paralleled by changes observed when the growth temperature was increased in the sequence 20, 30 and 40°C with acetate as the carbon and energy source. However, in cells grown at 40°C, as in the case of phenol-grown cells, resistance decreased. This effect could be caused by an increase in the fluidity of the target membrane since, by contrast, the increase in sensitivity induced by growth at 40°C can be partially annulled by provoking a decrease in fluidity by performing the inhibition measurements at a lower temperature (20°C). Both the degree of saturation of the fatty acids and the fluidity of the cytoplasmic membrane are features that should enable the resistance of Acinetobacter calcoaceticus 69-V to xenobiotics to be predicted.     

Diversity of Degradation Pathways of Some Aromatic Compounds by Phenotype and Genotype Testing in Acinetobacter Strains

Phenotype and genotype testing were combined in this study to identify the diversity of five Acinetobacter strains to degrade some low-molecular-weight aromatic compounds. Three groups were identified: Group one, A. calcoaceticus PHEA-2 and A. baumanii UMI-95, which had the ability to degrade catechol and protocatchuate, and could catabolize vanillic acid and phenol; Group two, Acinetobacter sp. MM1, which had the ability to degrade protocatchuate, but not catechol, just could catabolize vanillic acid; and Group three, A. lwoffi UMI-8, A. junii 85, which degraded neither catechol nor protocatchuate, not could catabolize vanillic acid or phenol. This revised version was published online in July 2006 with corrections to the Cover Date.     

<Emphasis Type="Italic">Acinetobacter brisouii</Emphasis> sp. nov., isolated from a wetland in Korea

A bacterial strain 5YN5-8^T was isolated from peat layer on Yongneup in Korea. Cells of strain 5YN5-8^T were strictly aerobic, Gram-negative, coccobacilli, non-spore forming, and non-motile. The isolate exhibited optimal growth at 28°C, pH 7.0, and 0–1% NaCl. Results of 16S rRNA gene sequence analyses indicated a close relationship of this isolate to Acinetobacter calcoaceticus (97.8% similarity for strain DSM 30006^T). It also exhibited 94.4–97.8% 16S rRNA gene sequence similarities to the validly published Acinetobacter species. The value for DNA-DNA hybridization between strain 5YN5-8^T and other members of the genus Acinetobacter ranged from 16 to 28%. Predominant cellular fatty acids were C_18:1 ω9c, summed feature 4 containing C_15:0 iso 2-OH and/or C_16:1 ω7c, and C_16:0. The DNA G+C content was 43.9 mol%. Phylogenetic, phenotypic, and chemotaxonomic data accumulated in this study revealed that the isolate could be classified in a novel species of the genus Acinetobacter. The name Acinetobacter brisouii sp. nov. is proposed for the novel species, with 5YN5-8^T (=KACC 11602^T = DSM 18516^T) as the type strain.     

Mild reductions in cytosolic NADP-dependent isocitrate dehydrogenase activity result in lower amino acid contents and pigmentation without impacting growth

Transgenic tomato (Solanum lycopersicum) plants were generated targeting the cytosolic NADP-dependent isocitrate dehydrogenase gene (SlICDH1) via the RNA interference approach. The resultant transformants displayed a relatively mild reduction in the expression and activity of the target enzyme in the leaves. However, biochemical analyses revealed that the transgenic lines displayed a considerable shift in metabolism, being characterized by decreases in the levels of the TCA cycle intermediates, total amino acids, photosynthetic pigments, starch and NAD(P)H. The plants showed little change in photosynthesis with the exception of a minor decrease in maximum photosynthetic efficiency (F _v/F _m), and a small decrease in growth compared to the wild type. These results reveal that even small changes in cytosolic NADP-dependent isocitrate dehydrogenase activity lead to noticeable alterations in the activities of enzymes involved in primary nitrate assimilation and in the synthesis of 2-oxoglutarate derived amino acids. These data are discussed within the context of current models for the role of the various isoforms of isocitrate dehydrogenase within plant amino acid metabolism.     

Isolierung von Cytochrom P-450 und des entsprechenden Reductasesystems aus Acinetobacter calcoaceticus

Cytochrome P–450 is found in soluble as well as in particulate fractions of n-alkane-induced cells of Acinetobacter calcoaceticus EB 104 as shown by differential centrifugation and; gelfiltration experiments. It is reduced by NADH in the presence of at least two soluble proteins. Particulate cytochrome P–450 was extracted by Triton X-100 and purified to homogeneity. The 80 fold enrichment resulted in a content of 19.0 nmol cytochrome P-450/mg protein. The maxima of the absolute spectra are 417 nm for the oxidized, 408 nm for the reduced and 448 nm for the CO complex of reduced cytochrome. A ferredoxin, identified by maxima of 415 and 460 nm in the absorption spectrum of the oxidized form and by the occurrence of acid-labile sulfur, as well as a corresponding NADH-dependent ferredoxin reductase were isolated independently from the same bacterial strain. Enzymatic reduction of purified cytochrome P–450 is mediated by these proteins, which are discussed as in vivo components of the cytochrome P–450 system of A. calcoaceticus EB 104.     

Isolation and characterization of arsenite-oxidizing bacteria from arsenic-contaminated soils in Thailand

Two hundred and eighty-eight arsenic-resistant bacteria were isolated by an enrichment culture method from a total of 69 arsenic-contaminated soil-samples collected from Dantchaeng district in Suphanburi province (47 samples), and from Ron Phiboon district in Nakhon Sri Thammarat province (22 samples), in Central and Southern Thailand, respectively. Twenty-four of the 288 isolated arsenic-resistant bacteria were found to be arsenite-oxidizing bacteria. On the basis of their morphological, cultural, physiological, biochemical and chemotaxonomic characteristics, and supported by phylogenetic analysis based upon their 16S rRNA gene sequences, they were divided into five groups, within the genera Acinetobacter, Flavobacterium, Pseudomonas, Sinorhizobium and Sphingomonas, respectively. Within genera, phylogenetic analysis using the 16S rRNA gene sequences suggested that they were comprised of at least ten species, five isolates being closely related to known bacteria (Acinetobacter calcoaceticus NCCB 22016^T, Pseudomonas plecoglossicida FPC951^T, Ps. knackmussii B13^T, Sinorhizobium morelense Lc04^T, and Sphingomonas subterranea IFO16086^T). The other five proposed species are likely to be new species closely related to Flavobacterium johnsoniae, Sinorhizobium morelense, Acinetobacter calcoaceticus and Pseudomonas plecoglossicida, but this awaits further characterization for confirmation of the taxonomic status. No overlap in isolated species or strains was observed between the two sites. The strain distribution and characterization are described.     

Degradation of long-chain n-alkanes by the yeast Candida maltosa

Summary Microsomal membrane fractions of the yeast Candida maltosa were investigated with respect to their ability to catalyse the oxidation of n-alkanes, fatty alcohols and fatty acids. Analysis of intermediates of n-hexadecane oxidation led to the conclusion that monoterminal attack was predominant, whereas diterminal oxidation proceeded as a minor reaction. The oxidation of long-chain primary alcohols to the corresponding aldehydes occurred without addition of nicotinamide adenine dinucleotide (phosphate) [NAD(P)⁺] and was accompanied by stoichiometric oxygen consumption and hydrogen peroxide production, suggesting that an alcohol oxidase instead of an NAD(P)⁺-requiring alcohol dehydrogenase catalysed these reactions. As shown for n-hexadecane, the hydroxylation of palmitic acid was found to be carbon monoxide-dependent, indicating involvement of a cytochrome P-450 system, as in the case of n-alkane hydroxylation.     

High levels of multiple metal resistance and its correlation to antibiotic resistance in environmental isolates of Acinetobacter

Forty strains of Acinetobacter were isolated from different environmental sources. All the strains were classified into four genospecies, i.e. A. baumannii (33 isolates), A. calcoaceticus (three isolates), A. junii (three isolates) and A. genospecies3 (one isolate). Susceptibility of these 40 strains to salts of 20 heavy metals and 18 antibiotics was tested by the agar dilution method. All environmental isolates of Acinetobacter were resistant to multiple metal ions (minimum 13 metal ions) while all but one of the strains were resistant to multiple antibiotics (minimum four antibiotics). The maximum number of strains were found to be sensitive to mercury (60% strains) while all strains were resistant to copper, lead, boron and tungsten even at 10 mm concentration. Salts of these four metal ions may be added to the growth medium to facilitate selective isolation of Acinetobacter. Rifampicin and nalidixic acid were the most toxic antibiotics, inhibiting 94.5 and 89.5% of the acinetobacters, respectively. A. genospecies3 was found to be the most resistant species, tolerating high concentrations of all the 20 metal ions and also to a greater number of antibiotics than any other species of Acinetobacter tested. An inhibitory concentration (10 mm) of Ni²⁺ and Zn²⁺ was observed to inhibit the growth of all of the clinical isolates but allowed the growth of the environmental isolates, facilitating the differentiation between pathogenic and non-pathogenic acinetobacters.