Slime Production by Pseudomonas aeruginosa

Two samples of slime obtained from Pseudomonas aeruginosa strains, IFO 3445 and No. 24, the latter which produced mucoid colonies on brain heart infusion agar as well as on the synthetic agar medium, were investigated for their physicochemical properties, primarily for their viscosities. Results obtained indicated that the principal component of the slime from strain IFO 3445 might be a deoxyribonucleic acid-like substance, while the slime from the mucoid strain No. 24 might be an alginic acid-like substance.     

Slime Production by Pseudomonas aeruginosa

Adequate experimental conditions for slime production by Pseudomonas aeruginosa were investigated using a cellophane plate method. Definite slime production was observed on heart infusion agar, brain heart infusion agar, yeast extract agar and synthetic agar, but not on nutrient agar. The addition of phosphate to the nutrient agar above 0.05% caused visible slime formation. Incubation at 37 C resulted in a higher yield of slime than at 25 C. Longer incubation seemed more favorable for slime production, while the pH reaction of the test media did not effect the slime yield. All the test cultures of P. aeruginosa produced large amounts of slime by this procedure. Cultures of Pseudomonas fluorescens, other Pseudomonas spp. and certain vibrios also produced slime under these experimental conditions.     

Pseudomonas aeruginosa outer membrane protein F produced inEscherichia coli retains vaccine efficacy

Pseudomonas aeruginosa outer membrane protein F was purified by extraction from polyacrylamide gels of cell envelope proteins of anEscherichia coli strain expressing the cloned gene for protein F. Antisera directed against protein F purified fromP. aeruginosa PAO1 reacted with thisE. coli strain by immunofluorescence assay and immunoblotting, whereas these antisera were nonreactive withE. coli strains lacking thePseudomonas protein F gene. The protein F purified from thisE. coli strain was used to immunize mice by intramuscular injection of 10 µg of protein F preparation on days 1 and 14, followed by burn and challenge of the mice on day 28. As compared with control mice immunized withE. coli K-12 lipopolysaccharide, immunization with theE. coli-derived protein F afforded significant protection against subsequent challenge with heterologous Fisher-Devlin immunotype 5 and 6 strains ofP. aeruginosa. Antisera from mice immunized with theE. coli-derived protein F reacted at bands corresponding to protein F and 2-mercaptoethanol-modified protein F upon immunoblotting against cell envelope proteins of the PAO1, immunotype 5, and immunotype 6 strains ofP. aeruginosa and theE. coli strain containing the cloned F gene, but failed to react at these sites in anE. coli strain lacking the F gene. These data demonstrate thatP. aeruginosa protein F produced inE. coli through genetic engineering techniques retains its vaccine efficacy in the complete absence of anyP. aeruginosa lipopolysaccharide.     

HETEROTROPHIC SLIMES IN FLOWING WATERS

1. While much attention has been paid to the ecology of macro-invertebrates in flowing water, the microbial ecology of such systems has been largely ignored and our knowledge of heterotrophic slimes in particular remains far from complete. Slime-forming organisms are ubiquitous in their distribution and are part of the normal riverine flora. Slime outbreaks occur in all types of organically enriched flowing fresh waters, regardless of their chemical nature. Slimes are predominantly of heterotrophs which require a constant supply of (i) a suitable carbon source, (ii) inorganic nutrients and in particular nitrogen and phosphorous, and possibly (iii) growth factors such as vitamins. Phosphorous is not a limiting factor for growth, with slimes developing in rivers with < 0·02 mg P l^-1. Other inorganic nutrients such as nitrogen can be used in various forms and are usually present in adequate amounts, even in unpolluted streams. Therefore occurrence appears to be most closely correlated with the presence of a source of available carbon. 2. The severity of outbreaks are not closely associated with soluble organic carbon content although there is a tendency for heavy growths to occur more frequently in more severely polluted waters. Low-molecular-weight sugars are clearly the causative agents of Sphaerotilus natans dominated slimes with higher molecular weight material such as starches not immediately effective as growth promoters. Mono- to penta-saccharides are mainly used by bacterial slimes while fungal components utilize fatty acids up to C₈. It is not possible to adopt a nationwide BOD₅ standards to control slime outbreaks as even small increases in river BOD₅ (< 1·0 mg l_-1) can support slime growth. There is a need to develop new methods of assessing the slime-promoting capability of effluents such as measuring the readily degradable low-molecular-weight carbon compounds, so that threshold concentrations of soluble organic carbon below which slime will not develop can be determined. 3. The effect of effluent enrichment on slime growth diminishes downstream as there is a tendency for the soluble carbohydrate to mix and dilute. The slime also metabolizes the carbohydrate, reducing the concentration by up to 60 % depending on the stage of slime development, thus limiting its own proliferation. This is the typical pattern of self-purification in flowing waters. 4. The taxonomy of all the slime-forming species are poorly understood as is the ecology of slimes. Species composition of slimes vary temporally and spatially within individual rivers. The primary factors affecting composition are nutrient type and water velocity, although pH determines whether a slime is either predominantly fungal or bacterial. The rate of transfer of oxygen and nutrients is dependent on water velocity with zoogloeal forms predominating as velocity falls to < 0·05 m s_-1. More details of the effects of water velocity and other environmental factors on all the slime-forming organisms is required. 5. The effects of specific environmental factors on slime growth have been determined primarily from laboratory-based studies, often using pure cultures on solid medium or batch culture methods. Clearly it has been difficult to relate these results to what is happening in the field. Little quantitative information on the productivity of slimes exist and the energy budgets or role of slimes in the self-purification process of rivers is largely unknown. The effects of temperature, pH, dissolved oxygen concentration, water velocity, solar energy input and grazing on the relationship between organic nutrient concentration and slime growth needs to be fully understood. Therefore there is a need for both field-based flow channel and field studies using mixed slime populations to accurately model the effects of environmental factors on slime development. Formation of such models is a prerequisite to the development of control strategies. 6. Due to slower oxidation rates at lower temperatures and reduced sloughing resulting in more luxuriant growths, slimes are generally considered to be more frequent and extensive in winter. However this is clearly not the case with outbreaks far more abundant in the summer due to the smaller flows reducing the dilution factor of effluents, and the enhanced temperature and suppressed oxygen concentration of the water, reducing competition and grazing. 7. The presence of slimes is not always detrimental, the major effect is unsightly appearance and reduced amenity value. Slime-forming organisms are predominantly aerobic and the rate of oxygen consumption of slimes is directly related to the dissolved oxygen concentration of the water. It would appear that slimes rarely cause deoxygenation, although sudden increases in water temperature which lowers the solubility of oxygen or enhanced chemical oxygen demand of the effluent due to reduced dilution, may cause total oxygen utilization. 8. The effects of slime growths on the aquatic environment are numerous and cumulative, especially in relation to salmonid fisheries. Nearly all pollutants that are released into the environment will enter surface waters at some stage, so the ability of heterotrophic slimes to rapidly accumulate heavy metals and perhaps other pollutants by various sorption processes will result in metals being concentrated and transferred along the food chain. This will eventually result in increased residual metal concentrations in fish or toxic concentrations of metals being accumulated in macro-invertebrates normally eaten by fish. Metals can be transported out of the polluted zone via sloughed floes and be released back in to solution downstream of the site originally affected. 9. The severity of problems associated with outbreaks increase with the length of the slime growth, with the majority of the longer outbreaks (> 5 km) resulting in oxygen depletion, increased siltation, alteration in flow pattern, increase in sloughed biomass, reduction in species diversity, destruction and reduction in habitat diversity and the elimination of fisheries. Case studies on the effects of slime growth, especially those causing fish kills, need to be carefully analysed and published. 10. The potential of heterotrophic slimes in biotechnology and wastewater treatment has yet to be fully realized. The ability to grow rapidly, producing considerable biomass rich in protein could be utilized. The sorption of heavy metals by all the slime-forming organisms but especially by the iron and manganese bacteria, could be used for the removal of low concentrations of metals in wastes, treatment of metal-rich effluents or for metal recovery. The property of removing phosphorous and nitrogen from solution should also be further considered. 11. No adequate control measures are available except for full treatment of effluents prior to discharge. Even traces of low-molecular-weight carbon compounds will result in slime development. Inadequate partial treatment may enhance slime growth by partially breaking down the effluent and releasing slime-promoting compounds. Intermittent discharge can reduce the standing crop of slime per unit surface area but as the total biomass supported by an effluent will remain the same, the slime will be extended over a greater length of river. Bacterial slimes are assemblages of filamentous and dispersed bacteria, and are far more common than fungal or algal dominated slimes. The two slime-forming organisms S. natans and zoogloeal bacteria are the major components of the majority of heterotrophic slimes, therefore any attempt at control should be aimed at these two species.     

Structure and Composition of Biological Slimes on Paper and Board Machines

Biological slimes (biofilms) collected from the wet end of paper and board machines were examined by electron microscopy and analyzed for fatty acid composition, neutral sugar composition, and ATP. Electron microscopy revealed minuscule prokaryotic organisms (diameter, 0.2 to 0.4 μm). Larger cells morphologically resembling Sphaerotilus and Leptothrix spp. were found in slimes from machines using recycled fiber or unbleached pulp. The bacteria were embedded in a slimy matrix and often contained reserve materials microscopically resembling poly-β-hydroxybutyrate and glycogen. Fatty acid analysis of the slimes revealed bacterial signature fatty acids in concentrations equivalent to the presence of 2 × 10¹⁰ to 2.6 × 10¹² (average, 7 × 10¹¹) bacterial cells (live and dead) per g (dry weight) of slime. The slimes contained several known components of bacterial polysaccharides in addition to glucose, indicating that the slime body consisted of bacterial polysaccharides. The slimes contained uronic acids equivalent to a binding capacity of 12.5 to 50 μmol of divalent cations per g (dry weight) of slime. The uronic acid-containing polysaccharides may be responsible for the accumulation of heavy metals in the slime. Calculation of the ATP contents of the slimes resulted in an estimate of 5 × 10¹² cells per g (dry weight) of slime when calibrated with pure bacterial cultures isolated from the slimes. From electron micrographs, an estimate ranging from 1 × 10¹⁰ to 1.5 × 10¹² (average, 4 × 10¹¹) cells per g (dry weight) of slime was obtained.     

Induction of cell fusion by a factor released by the cellular slime mold Polysphondylium pallidum

Heterokaryons and hybrid cells, which are extremely useful for research in cell biology, can be produced artificially by treating cells with either polyethylene glycol or certain inactivated viruses that alter the plasma membrane. We report here a novel cell-fusion inducing factor secreted by CK-8 strain cells of cellular slime mold Polysphondylium pallidum. Treatment of other strains or other species of cellular slime molds, such as NC-4 of Dictyostelium discoideum with the diluted fraction, containing molecules larger than 50 kDa, of the conditioned medium of CK-8 cell culture induces cell fusion at high frequency and produces multinucleated large cells. This cell fusion is inducible between cells of either a single strain or of two different strains of cellular slime molds.Abbreviations BSS Bonner's salt solution - CM conditioned medium - EDTA ethylenediaminetetraacetic acid - F2 fraction containing cell-fusion induction factor - Mr molecular mass     

Response of RP1+ and RP1− strains ofEscherichia coli to antibacterial agents and transfer of resistance toPseudomonas aeruginosa

The sensitivity of strains ofEscherichia coli, with and without the RP1 R-factor, to antibiotics and other antibacterial agents has been studied. RP1⁺ strains ofE. coli were resistant to kanamycin, carbenicillin, and tetracycline, resistance to the first two antibiotics being produced by destruction of the drugs. This resistance could be transferred to two strains ofPseudomonas aeruginosa. The parent strain ofE. coli UB 1005, its two mutant strains (DC2 and DC3), and two of the strains with the RP1 R-factor showed a similar order of sensitivity to phenylmercuric nitrate, chlorhexidine, thiomersal, and mercuric chloride.E. coli strains DC2 and DC2 (RP1⁺) were the most sensitive to benzalkonium chloride and cetrimide. RP1⁺ strains were more resistant than RP1⁻ strains to lysozyme-ethylenediaminetetraacetic acid, but treatment of the former strains with acriflavine rendered the cells more sensitive to the lytic system. There was no evidence thatP. aeruginosa (RP1⁺) strains possessed increased resistance to polymyxin or to disinfectants, although they became somewhat less sensitive to lysozyme-ethylenediaminetetraacetic acid.     

Identification of a slime exopolysaccharide depolymerase in mucoid strains ofPseudomonas aeruginosa

Strains ofPseudomonas aeruginosa recovered from pulmonary infections in cystic fibrosis (CF) patients are often mucoid in appearance owing to the secretion of a viscous slime exopolysaccharide (EPS). Unlike most mucoid isolates, strains WcM#2, P10, and P11 produce mucoid colonies after 24 h of incubation at 37°C, which become nonmucoid upon further incubation; this suggests the presence of a slime-degrading enzyme or depolymerase. Using both qualitative and quantitative assays, the presence of a slime EPS depolymerase was confirmed in each of these three strains as well as in four of four additional mucoid strains. Depolymerase activity was lower but still detectable in four of four nonmucoid strains. Enzyme preparations from strains WcM#2, P10, and P11 were active on most, but not all, slime EPS preparations fromP. aeruginosa strains, as well as sodium alginate; greater activity was observed on substrates after deacetylation. Comparisons are made between the enzyme described in this study and previous reports of slime EPS depolymerase in mucoid strains ofP. aeruginosa.     

Transformation of Pseudomonas aeruginosa and Escherichia coli with resistance plasmid DNA: formation of smaller conjugative plasmids from RPI.

Summary Sheared DNA from RPI, an R plasmid from a strain of Pseudomonas aeruginosa, was used to transform other strains of P. aeruginosa and Escherichia coli. From transformed cells other plasmids like RPI were isolated. These deletion plasmids were conjugally transferrable and confer resistance mainly against carbenicillin and tetracycline.     

Co-Existence of Multidrug-Resistant and -Susceptible Strains of Pseudomonas aeruginosa from a Single Clinical Isolate

Pseudomonas aeruginosa is a leading cause of hospital-acquired infections and difficult to treat due to acquired-resistance to multiple antibiotics. A pair of strains, M38100A and M38100B, previously identified from a single clinical isolate of P. aeruginosa was investigated to understand phenotypic and genotypic characteristics. Results revealed that the pair of strains was very similar for serum susceptibility, growth rate in a complex medium (Luria–Bertani), RAPD-genotype profiles, status of genes encoding type III secretion toxins, and no extra-chromosomal DNA. However, antibiotic susceptibility of the strain M38100B showed resistant to all tested-antibiotics while the strain M38100A showed susceptible to the same tested-antibiotics as similar levels of P. aeruginosa PAO1. The strain M38100B exhibited no growth in a minimal medium as a sole carbon and nitrogen source of glutamate while the strain M38100A grew well in the same minimal medium. These results suggest that multidrug resistance of the strain M38100B may be caused by multiple mutations on its genomic DNA and a precursor stage for a homogeneous multidrug resistant population.     

Psychrotrophic,lactic acid-producing bacteria from anoxic waters in Ace Lake,Antarctica; Carnobacterium funditum sp. nov. and Carnobacterium alterfunditum sp. nov.

Heterofermentative, lactic acid-producing, gram-positive, motile bacteria were isolated from the waters of Ace Lake, Antarctica. All strains produced virtually only l(+)lactic acid from d(+)glucose. d(–)ribose was fermented to lactic, acetic, and formic acids, and ethanol. Cell walls contained meso-diaminopimaleic acid. The strains did not grow at 30°C and were psychrotrophic. Whole cells contained 18:1cis 9 as a major component of their fatty acids. At 20°C, the strains grew better anaerobically than aerobically and all strains lacked catalase, oxidase and respiratory lipoquinones. DNA that coded for most of the 16S rRNA gene of one of the strains was amplified by the polymerase chain reaction and sequenced. The strain was phylogenetically most closely related to Carnobacterium mobile (K_nuc=0.0214). The isolates separated into two phenotypes. DNA/DNA homology studies determined on a representative from each phenotype showed low homology between the phenotypes (38±8%), and with Carnobacterium mobile (26±2%, 34±2%). Carnobacterium funditum sp. nov. produced acid from mannitol, trehalose, but not amygdalin. The G+C content of the DNA was 32–34%, and the Type strain is DSM 5970 (=ACAM 312). Carnobacterium alterfunditum sp. nov. produced acid weakly from amygdalin but not from mannitol or trehalose. The G+C content was 33–34%, and the Type strain is DSM 5972 (=ACAM 313).     

Antimicrobial activity of <Emphasis Type="Italic">Bacillus megaterium</Emphasis> strains

A bacterial strain with a high level of antimicrobial activity was isolated from soil and identified as Bacillus megaterium. Production of antibiotics by nine strains of this species from the collection of the State Research Institute for Genetics and Selection of Industrial Microorganisms was investigated. In submerged cultures, nine out of ten B. megaterium strains were found to produce antibacterial antibiotics differing in their spectra of action. Physicochemical characteristics of five compounds were described. Three of them belonged to peptide antibiotics. All five compounds were active against the methicillin-resistant strain Staphylococcus aureus INA 00761. Three of them were shown to be the previously undescribed compounds. Antibiotics produced by various B. megaterium strains were also active against the Leuconostoc mesenteroides VKPM B-4177 strain resistant to glycopeptide antibiotics and against gram-negative bacteria Pseudomonas aeruginosa ATCC 27853 and Escherichia coli ATCC 25922.     

Isolation and Characterization of Three Porin-Like Proteins from Vibrio vulnificus: Effect of Different Growth Media on Their Production

The effect of the culture media on the composition of the outer membrane protein of Vibrio vulnificus strain 393 from human blood was examined. Only one major outer membrane protein, with an apparent molecular weight of 37,000 (37K protein) and 34,000 (34K protein), was formed in the cells grown in 3% NaCl-BHI broth and chemically defined medium, respectively. The production of one major outer membrane protein was also observed in other isolates from humans and asari clam when they were grown in 3% NaCl-BHI broth. On the other hand, three major outer membrane proteins, with apparent molecular weights of 48,000 (48K protein), 37,000 (37K protein), and 34,000 (34K protein), were produced in the cells grown in 3% NaCl-nutrient broth. Three proteins, 48K, 37K, and 34K from strain 393, were purified and the amino acid compositions were determined. Although there was a little difference in the composition of amino acid among three proteins, the amino acid compositions of the three porin-like proteins showed characteristic properties of the porins of Escherichia coli and Salmonella typhimurium. Immunoblot analysis of the outer membrane proteins from four vibrios, E. coli, and S. typhimurium using monospecific antisera against these three porin-like proteins showed that only the antiserum against 37K protein cross-reacted with the outer membrane proteins from all the strains tested.     

Biosurfactants,an help in the biodegradation of hexadecane? The case of <Emphasis Type="Italic">Rhodococcus</Emphasis> and <Emphasis Type="Italic">Pseudomonas</Emphasis> strains

The roles of the extracellular biosurfactants produced by two bacterial strains, Pseudomonas aeruginosa GL1 and Rhodococcus equi Ou2, in hexadecane uptake and biodegradation were compared. For this purpose, cell hydrophobicity and production of glycolipidic biosurfactants were evaluated during bacterial growth on hexadecane, as well the effects of these biosurfactants on culture supernatants properties i.e., surface and interfacial tensions, and emulsification and pseudosolubilization capacities. The results showed that the role of biosurfactants was different in these two strains and was directly related to the hydrophobicity of the bacterial cells concerned. Extracellular biosurfactants produced by strain R. equi Ou2 had only a minor role in hexadecane degradation. Direct interfacial accession appeared to be the main mechanism for hexadecane uptake by the hydrophobic cells of strain R. equi Ou2. On the contrary, the biosurfactants produced by P. aeruginosa GL1 were required for growth on hexadecane, and their pseudosolubilization capacity rather than their emulsification capacity was involved in substrate degradation, allowing uptake from hexadecane micelles by the hydrophilic cells of this bacterium. The roles of biosurfactants thus differ widely among bacteria degrading hydrophobic compounds. J.-P. Vandecasteele—in retirement     

The importance of morphological versus chemical defences for the bloom-forming cyanobacterium Microcystis against amoebae grazing

Amoebae grazing can be an important loss factor for blooms of the common cyanobacterium Microcystis. Some Microcystis strains seem to be protected against amoebae grazing, but it is unclear whether this is achieved by their colony morphology or biochemically. These factors were investigated in grazing experiments using two Microcystis-grazing amoebae (Korotnevella sp. and Vannella sp.) and two Microcystis strains with differing colony morphology (aeruginosa and viridis morphotype) and different sensitivity to amoebae grazing. Amoebae did not increase in density and failed to reduce the growth rate of cultures of the amoebae insensitive viridis strain, irrespective of whether the Microcystis strain was colonial or unicellular. This suggests that the extended mucilage matrix surrounding viridis colonies is not the main defence mechanism against amoebae grazing. At the same time, the growth rate of both unicellular and colonial cultures of the amoebae-sensitive aeruginosa strain was heavily reduced by the growing amoebae. The addition of filtered viridis-conditioned medium to aeruginosa cultures significantly decreased both amoebae growth and its effect on aeruginosa growth rates, which indicates that extracellular compounds constitutively produced by viridis are at least partially responsible for their insensitivity to amoebae grazing. These results demonstrate the potential importance of chemical interactions between lower trophic levels (protists) for Microcystis bloom dynamics.     

Copper Uptake by <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> Isolated from Infected Burn Patients

Pseudomonas aeruginosa was isolated from infected burn patients and characterized by standard biochemical tests. The in vitro copper uptake was compared between this isolated pathogenic strain and two non-pathogenic control strains of Gram positive bacteria Bacillus thuringiensis strain Israelis as well as Gram negative bacteria Enterobacter aerogenes. Maximum copper uptake of 470 ppm/g biomass was obtained by P. aeruginosa strain, while the control strains B. thuringiensis and Enterobacter aerogenes had copper uptake of 350 and 383 ppm/g biomass, respectively. However, the lowest copper uptake (60 ppm/g biomass) was observed with another control the saprophytic strain Pseudomonas (Shewanella) putrefaciens. A further investigation regarding the effect of copper toxicity on bacterial growth, gave an MIC score of 600 ppm for P. aeruginosa strain compared to 460 and 300 ppm for the two Gram positive and Gram negative control strains, respectively. In tandem with these in vitro findings, blood analysis on burn patients infected with P. aeruginosa has indicated a selective decrease of copper (hypocupremia) and ceruloplasmin plasma levels. The iron metabolism was also affected by this copper deprivation leading to a similar decrease in plasma levels of PCV, iron, total iron binding capacity, and transferrin. All these hematological changes were significantly different (P < 0.05) from the matched group of non-infected burn patients. The observed hypocupremia in infected burn patients was attributed to demanding scavenger ability by P. aeruginosa strain for the copper of plasma.     

Toxin composition variations in cultures of Alexandrium species isolated from the coastal waters of southern China

The composition of the paralytic shellfish toxins (PSTs) of five Alexandrium tamarense strains isolated from the coastal waters of southern China and one Alexandrium minutum strain from Taiwan Island were investigated. A. tamarense CI01 and A. tamarense Dapeng predominantly produced C2 toxin (over 90%) with trace amounts of C1 toxin (C1), gonyautoxin-2 (GTX2) and GTX3; two strains of A. tamarense HK9301 maintained in different locations produced C1-4 toxins and GTX1, 4, 5 and 6; no PSTs were found in A. tamarense NEW, while A. minutum TW produced only GTX1-4. The toxin compositions of cultured A. tamarense strains did not vary as much during different growth phases as did the toxin composition of A. minutum TW. The toxin compositions of A. tamarense HK9301-1 did not change significantly under different salinity, light intensity, and nitrate and phosphate levels in the culture medium, although the toxin productivity varied expectably. Another strain HK9301-2 maintained in a different location produced much less toxins with a considerably different toxin composition. Under similar culture maintenance conditions for 3 years, the toxin profiles of A. tamarense HK9301-1 did not change as much as did A. tamarense CI01. Our results indicate that toxin compositions of the dinoflagellate strains are strain-specific and are subject to influence by nutritional and environmental conditions but not as much by the growth phase. Use of toxin composition in identifying a toxigenic strain requires special caution.     

The Effect of Rhamnolipid Biosurfactant Produced by <Emphasis Type="Italic">Pseudomonas fluorescens</Emphasis> on Model Bacterial Strains and Isolates from Industrial Wastewater

In this study, the effect of rhamnolipid biosurfactant produced by Pseudomonas fluorescens on bacterial strains, laboratory strains, and isolates from industrial wastewater was investigated. It was shown that biosurfactant, depending on the concentration, has a neutral or detrimental effect on the growth and protein release of model Gram (+) strain Bacillus subtilis 168. The growth and protein release of model Gram (−) strain Pseudomonas aeruginosa 1390 was not influenced by the presence of biosurfactant in the medium. Rhamnolipid biosurfactant at the used concentrations supported the growth of some slow growing on hexadecane bacterial isolates, members of the microbial community. Changes in cell surface hydrophobicity and permeability of some Gram (+) and Gram (−) isolates in the presence of rhamnolipid biosurfactant were followed in experiments in vitro. It was found that bacterial cells treated with biosurfactant became more or less hydrophobic than untreated cells depending on individual characteristics and abilities of the strains. For all treated strains, an increase in the amount of released protein was observed with increasing the amount of biosurfactant, probably due to increased cell permeability as a result of changes in the organization of cell surface structures. The results obtained could contribute to clarify the relationships between members of the microbial community as well as suggest the efficiency of surface properties of rhamnolipid biosurfactant from Pseudomonas fluorescens making it potentially applicable in bioremediation of hydrocarbon-polluted environments.     

Production of 10-Hydroxy-8(E)-Octadecenoic Acid from Oleic Acid Conversion by Strains of Pseudomonas aeruginosa

Eighteen Pseudomonas aeruginosa strains were examined for their ability to convert oleic acid to produce 10-hydroxy-8(E)-octadecenoic acid (HOD), which was structurally confirmed by GC-MS, NMR, and FTIR. There were no substantial amounts of other new compounds found in the fermentation broths in addition to HOD and 7,10-dihydroxy-8(E)-octadecenoic acid (DOD). The results demonstrated that P. aeruginosa strains possessed varying levels of activity for producing HOD. Under the experimental conditions, strain NRRL B-14938 isolated from sheep manure was the best HOD producer exhibiting the highest HOD to DOD product ratio in the medium most suitable for purifying HOD. Using strain B-14938 as a model system for further characterization, optimum conditions for producing HOD were found to be at 26°C and pH 7.0 after 60 h of reaction time using a medium containing EDTA as a chelating agent. This study has identified a high-yielding P. aeruginosa strain and provided the reaction characteristics needed to develop a scale-up production process of HOD for testing its properties and potential new uses.     

Diversity of Oleic Acid,Ricinoleic Acid and Linoleic Acid Conversions Among <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> Strains*

Sixteen Pseudomonas aeruginosa strains, including patent strain NRRL B-18602, three recent isolates from composted materials amended with ricinoleic acid, and 12 randomly selected from the holdings of the ARS Culture Collection, were examined for their fatty acid converting abilities. The study examined the bioconversion of oleic acid to 7,10-dihydroxy-8(E)-octadecenoic acid (DOD) and ricinoleic acid to 7,10,12-trihydroxy-8(E)-octadecenoic acid (TOD). A new DOD-like compound from linoleic acid was observed. All strains except NRRL B-247 exhibited varying levels of DOD production. NRRL B-1000, NRRL B-18602 and NRRL B-23258 with yields up to 84% were among the best DOD producers. TOD production generally paralleled DOD production at a relatively lower yield of up to 15%. Strains NRRL B-1000 and NRRL B-23260 were the best TOD producers. A DOD-like product in low yields was obtained from linoleic acid. The fatty acid bioconversion capability was related neither to growth rate nor to variation in the greenish pigmentation of the strains. Production of significant quantities of DOD and TOD from oleic and ricinoleic acids, respectively, appeared to be a characteristic trait of P. aeruginosa strains. A number of highly effective strains for DOD production were identified.