Metallic nanoparticle actions on the outer layer structure and properties of Bacillus cereus and Staphylococcus epidermidis.

Although the antimicrobial activity of nanoparticles (NPs) penetrating inside the cell is widely recognised, the toxicity of large NPs (>10 nm) that cannot be translocated across bacterial membranes remains unclear. Therefore, this study was performed to elucidate the direct effects of Ag-NPs, Cu-NPs, ZnO-NPs and TiO2-NPs on relative membrane potential, permeability, hydrophobicity, structural changes within chemical compounds at the molecular level and the distribution of NPs on the surfaces of the bacteria Bacillus cereus and Staphylococcus epidermidis. Overall analysis of the results indicated the different impacts of individual NPs on the measured parameters in both strains depending on their type and concentration. B. cereus proved to be more resistant to the action of NPs than S. epidermidis. Generally, Cu-NPs showed the most substantial toxic effect on both strains; however, Ag-NPs exhibited negligible toxicity. All NPs had a strong affinity for cell surfaces and showed strain-dependent characteristic dispersion. ATR-FTIR analysis explained the distinctive interactions of NPs with bacterial functional groups, leading to macromolecular structural modifications. The results presented provide new and solid evidence for the current understanding of the interactions of metallic NPs with bacterial membranes.

Comprehensive phenomic and genomic studies of the species, Pectobacterium cacticida and proposal for reclassification as Alcorniella cacticida comb. nov.

Introduction: Pectobacterium cacticida was identified as the causative agent of soft rot disease in cacti. Due to a high potential of spread in the face of global warming, the species poses a significant threat to horticultural and crop industry. The aim of this study was to revise the genomic, physiology and virulence characteristics of P. cacticida and update its phylogenetic position within the Pectobacterium genus. Methods: Whole genome sequences of five P. cacticida strains were obtained and subjected to comprehensive genomic and phylogenomic data analyses. We assessed the presence of virulence determinants and genes associated with host and environmental adaptation. Lipidomic analysis, as well as biochemical and phenotypic assays were performed to correlate genomic findings. Results: Phylogenomic analysis revealed that P. cacticida forms a distinct lineage within the Pectobacterium genus. Genomic evaluation uncovered 516 unique proteins, most of which were involved in cellular metabolism. They included genes of carbohydrate metabolism and transport and ABC transporters. The main differing characteristics from other Pectobacterium species were the lack of a myo-inositol degradation pathway and the presence of the malonate decarboxylase gene. All tested strains were pathogenic towards Opuntia spp., chicory, Chinese cabbage, and potato, but exhibited only mild pathogenicity towards carrot. Discussion: This study sheds light into the genomic characteristics of P. cacticida and highlights the pathogenic potential of the species. Unique genes found in P. cacticida genomes possibly enhance the species' survival and virulence. Based on phylogenomic analyses, we propose the reclassification of P. cacticida to a new genus, Alcorniella comb. nov.

Microwave Irradiation vs. Structural, Physicochemical, and Biological Features of Porous Environmentally Active Silver-Silica Nanocomposites.

Heavy metals and other organic pollutants burden the environment, and their removal or neutralization is still inadequate. The great potential for development in this area includes porous, spherical silica nanostructures with a well-developed active surface and open porosity. In this context, we modified the surface of silica spheres using a microwave field (variable power and exposure time) to increase the metal uptake potential and build stable bioactive Ag2O/Ag2CO3 heterojunctions. The results showed that the power of the microwave field (P = 150 or 700 W) had a more negligible effect on carrier modification than time (t = 60 or 150 s). The surface-activated and silver-loaded silica carrier features like morphology, structure, and chemical composition correlate with microbial and antioxidant enzyme activity. We demonstrated that the increased sphericity of silver nanoparticles enormously increased toxicity against E. coli, B. cereus, and S. epidermidis. Furthermore, such structures negatively affected the antioxidant defense system of E. coli, B. cereus, and S. epidermidis through the induction of oxidative stress, leading to cell death. The most robust effects were found for nanocomposites in which the carrier was treated for an extended period in a microwave field.

Undesirable consequences of the metallic nanoparticles action on the properties and functioning of Escherichia coli, Bacillus cereus and Staphylococcus epidermidis membranes.

Controversial and inconsistent findings on the toxicity of metallic nanoparticles (NPs) against many bacteria are common in recorded studies; therefore, further advanced experimental work is needed to elucidate the mechanisms underlying nanotoxicity. This study deciphered the direct effects of Ag-NPs, Cu-NPs, ZnO-NPs and TiO2-NPs on membrane permeability, cytoplasmic leakage, ATP level, ATPase activity and fatty acid profiling of Escherichia coli, Bacillus cereus and Staphylococcus epidermidis as model microorganisms. A multifaceted analysis of all collected results indicated the different influences of individual NPs on the measured parameters depending on their type and concentration. Predominantly, membrane permeability was correlated with increased cytoplasmic leakage, reduced total ATP levels and ATPase activity. The established fatty acid profiles were unique and concerned various changes in the percentages of hydroxyl, cyclopropane, branched and unsaturated fatty acids. Decisively, E. coli was more susceptible to changes in measured parameters than B. cereus and S. epidermidis. Also, it was established that ZnO-NPs and Cu-NPs had a major differentiating impact on studied parameters. Additionally, bacterial cell imaging using scanning electron microscopy elucidated different NPs distributions on the cell surface. The presented results are believed to provide novel, valuable and accumulated knowledge in the understanding of NPs action on bacterial membranes.

Evaluation of the Effects of Ag, Cu, ZnO and TiO2 Nanoparticles on the Expression Level of Oxidative Stress-Related Genes and the Activity of Antioxidant Enzymes in Escherichia coli, Bacillus cereus and Staphylococcus epidermidis.

Although the molecular response of bacteria exposed to metal nanoparticles (NPs) is intensively studied, many phenomena related to their survival, metal uptake, gene expression and protein production are not fully understood. Therefore, this work aimed to study Ag-NPs, Cu-NPs, ZnO-NPs and TiO2-NPs-induced alterations in the expression level of selected oxidative stress-related genes in connection with the activity of antioxidant enzymes: catalase (CAT), peroxidase (PER) and superoxide dismutase (SOD) in Escherichia coli, Bacillus cereus and Staphylococcus epidermidis. The methodology used included: the extraction of total RNA and cDNA synthesis, the preparation of primers for selected housekeeping and oxidative stress genes, RT-qPCR reaction and the measurements of CAT, PER and SOD activities. It was established that the treatment of E. coli and S. epidermidis with NPs resulted mainly in the down-regulation of targeted genes, whilst the up-regulation of genes was confirmed in B. cereus. The greatest differences in the relative expression levels of tested genes occurred in B. cereus and S. epidermidis treated with TiO2-NPs, while in E. coli, they were observed under ZnO-NPs exposure. The changes found were mostly related to the expression of genes encoding proteins with PER and CAT-like activity. Among NPs, ZnO-NPs and Cu-NPs increased the activity of antioxidants in E. coli and B. cereus. In turn, TiO2-NPs had a major effect on enzymes activity in S. epidermidis. Considering all of the collected results for tested bacteria, it can be emphasised that the impact of NPs on the antioxidant system functioning was dependent on their type and concentration.

Insight into the Antibacterial Activity of Selected Metal Nanoparticles and Alterations within the Antioxidant Defence System in Escherichia coli, Bacillus cereus and Staphylococcus epidermidis.

The antimicrobial activity of nanoparticles (NPs) is a desirable feature of various products but can become problematic when NPs are released into different ecosystems, potentially endangering living microorganisms. Although there is an abundance of advanced studies on the toxicity and biological activity of NPs on microorganisms, the information regarding their detailed interactions with microbial cells and the induction of oxidative stress remains incomplete. Therefore, this work aimed to develop accurate oxidation stress profiles of Escherichia coli, Bacillus cereus and Staphylococcus epidermidis strains treated with commercial Ag-NPs, Cu-NPs, ZnO-NPs and TiO2-NPs. The methodology used included the following determinations: toxicological parameters, reactive oxygen species (ROS), antioxidant enzymes and dehydrogenases, reduced glutathione, oxidatively modified proteins and lipid peroxidation. The toxicological studies revealed that E. coli was most sensitive to NPs than B. cereus and S. epidermidis. Moreover, NPs induced the generation of specific ROS in bacterial cells, causing an increase in their concentration, which further resulted in alterations in the activity of the antioxidant defence system and protein oxidation. Significant changes in dehydrogenases activity and elevated lipid peroxidation indicated a negative effect of NPs on bacterial outer layers and respiratory activity. In general, NPs were characterised by very specific nano-bio effects, depending on their physicochemical properties and the species of microorganism.

Adaptation of phenol-degrading Pseudomonas putida KB3 to suboptimal growth condition: A focus on degradative rate, membrane properties and expression of xylE and cfaB genes.

Detailed characterization of new Pseudomonas strains that degrade toxic pollutants is required and utterly necessary before their potential use in environmental microbiology and biotechnology applications. Therefore, phenol degradation by Pseudomonas putida KB3 under suboptimal temperatures, pH, and salinity was examined in this study. Parallelly, adaptive mechanisms of bacteria to stressful growth conditions concerning changes in cell membrane properties during phenol exposure as well as the expression level of genes encoding catechol 2,3-dioxygenase (xylE) and cyclopropane fatty acid synthase (cfaB) were determined. It was found that high salinity and the low temperature had the most significant effect on the growth of bacteria and the rate of phenol utilization. Degradation of phenol (300 mg L-1) proceeded 12-fold and seven-fold longer at 10 °C and 5% NaCl compared to the optimal conditions. The ability of bacteria to degrade phenol was coupled with a relatively high activity of catechol 2,3-dioxygenase. The only factor that inhibited enzyme activity by approximately 80% compared to the control sample was salinity. Fatty acid methyl ester (FAMEs) profiling, membrane permeability measurements, and hydrophobicity tests indicated severe alterations in bacteria membrane properties during phenol degradation in suboptimal growth conditions. The highest values of pH, salinity, and temperature led to a decrease in membrane permeability. FAME analysis showed fatty acid saturation indices and cyclopropane fatty acid participation at high temperature and salinity. Genetic data showed that suboptimal growth conditions primarily resulted in down-regulation of xylE and cfaB gene expression.

Impact of an Engineered Copper-Titanium Dioxide Nanocomposite and Parent Substrates on the Bacteria Viability, Antioxidant Enzymes and Fatty Acid Profiling.

Due to the systematic increase in the production of nanomaterials (NMs) and their applications in many areas of life, issues associated with their toxicity are inevitable. In particular, the performance of heterogeneous NMs, such as nanocomposites (NCs), is unpredictable as they may inherit the properties of their individual components. Therefore, the purpose of this work was to assess the biological activity of newly synthesized Cu/TiO2-NC and the parent nanoparticle substrates Cu-NPs and TiO2-NPs on the bacterial viability, antioxidant potential and fatty acid composition of the reference Escherichia coli and Bacillus subtilis strains. Based on the toxicological parameters, it was found that B. subtilis was more sensitive to NMs than E. coli. Furthermore, Cu/TiO2-NC and Cu-NPs had an opposite effect on both strains, while TiO2-NPs had a comparable mode of action. Simultaneously, the tested strains exhibited varied responses of the antioxidant enzymes after exposure to the NMs, with Cu-NPs having the strongest impact on their activity. The most considerable alternations in the fatty acid profiles were found after the bacteria were exposed to Cu/TiO2-NC and Cu-NPs. Microscopic images indicated distinct interactions of the NMs with the bacterial outer layers, especially in regard to B. subtilis. Cu/TiO2-NC generally proved to have less distinctive antimicrobial properties on B. subtilis than E. coli compared to its parent components. Presumably, the biocidal effects of the tested NMs can be attributed to the induction of oxidative stress, the release of metal ions and specific electrochemical interactions with the bacterial cells.

Arthrospiribacter ruber gen. nov., sp. nov., a novel bacterium isolated from Arthrospira cultures.

Polyphasic analysis of ten isolates of the red-pigmented bacteria isolated from ten Arthrospira cultures originating from different parts of the world is described. The 16S rRNA analysis showed <95 % identity with the known bacteria on public databases, therefore, additional analyses of fatty acids profiles, MALDI-TOF/MS, genome sequencing of the chosen isolate and following phylogenomic analyses were performed. Gram-stain-negative, strictly aerobic rods were positive for catalase, negative for oxidase, proteolytic and urease activity. Major fatty acids were 15 : 0 iso, 17:0 iso 3 OH and 17:1 iso w9c/16:0 10-methyl. The whole phylogenomic analyses revealed that the genomic sequence of newly isolated strain DPMB0001 was most closely related to members of Cyclobacteriaceae family and clearly indicated distinctiveness of newly isolated bacteria. The average nucleotide identity and in silico DNA-DNA hybridisation values were calculated between representative of the novel strains DPMB0001 and its phylogenetically closest species, Indibacter alkaliphilus CCUG57479 (LW1)T (ANI 69.2 % is DDH 17.2 %) and Mariniradius saccharolyticus AK6T (ANI 80.02 % isDDH 26.1 %), and were significantly below the established cut-off <94 % (ANI) and <70 % (isDDH) for species and genus delineation. The obtained results showed that the analysed isolates represent novel genus and species, for which names Arthrospiribacter gen nov. and Arthrospiribacter ruber sp. nov. (type strain DPMB0001=LMG 31078=PCM 3008) is proposed.

Antibiotics in the Soil Environment-Degradation and Their Impact on Microbial Activity and Diversity.

Antibiotics play a key role in the management of infectious diseases in humans, animals, livestock, and aquacultures all over the world. The release of increasing amount of antibiotics into waters and soils creates a potential threat to all microorganisms in these environments. This review addresses issues related to the fate and degradation of antibiotics in soils and the impact of antibiotics on the structural, genetic and functional diversity of microbial communities. Due to the emergence of bacterial resistance to antibiotics, which is considered a worldwide public health problem, the abundance and diversity of antibiotic resistance genes (ARGs) in soils are also discussed. When antibiotic residues enter the soil, the main processes determining their persistence are sorption to organic particles and degradation/transformation. The wide range of DT50 values for antibiotic residues in soils shows that the processes governing persistence depend on a number of different factors, e.g., physico-chemical properties of the residue, characteristics of the soil, and climatic factors (temperature, rainfall, and humidity). The results presented in this review show that antibiotics affect soil microorganisms by changing their enzyme activity and ability to metabolize different carbon sources, as well as by altering the overall microbial biomass and the relative abundance of different groups (i.e., Gram-negative bacteria, Gram-positive bacteria, and fungi) in microbial communities. Studies using methods based on analyses of nucleic acids prove that antibiotics alter the biodiversity of microbial communities and the presence of many types of ARGs in soil are affected by agricultural and human activities. It is worth emphasizing that studies on ARGs in soil have resulted in the discovery of new genes and enzymes responsible for bacterial resistance to antibiotics. However, many ambiguous results indicate that precise estimation of the impact of antibiotics on the activity and diversity of soil microbial communities is a great challenge.

Degradation of 4-chlorophenol and microbial diversity in soil inoculated with single Pseudomonas sp. CF600 and Stenotrophomonas maltophilia KB2.

Soil contamination with chlorophenols is a serious problem all over the world due to their common use in different branches of industry and agriculture. The objective of this study was to determine whether bioaugmenting soil with single Pseudomonas sp. CF600 and Stenotrophomonas maltophilia KB2 and additional carbon sources such as phenol (P) and sodium benzoate (SB) could enhance the degradation of 4-chlorophenol (4-CP). During the degradation experiment, the number of bacteria as well as the structural and functional diversity of the soil microbial communities were determined. It was found that the most effective degradation of 4-CP in the soil was observed after it was inoculated with CF600 and the addition of SB. The biodegradation of five doses of 4-CP in this soil proceeded within 100 days. At the same time, the rate of the disappearance of 4-CP in the soil that had been bioaugmented with CF600 and contaminated with 4-CP and P was 5-6.5 times lower compared to its rate of disappearance in the soil that had been contaminated with 4-CP. The biodegradation of 4-CP in all of the treated and untreated soils was accompanied by a systematic decrease in the number of heterotrophic bacteria (THB) ranging between 13 and 40%. It was also proven that the tested aromatic compounds affected the soil microbial community structure through an increase in the marker fatty acids for Gram-negative bacteria (BG-) and fungi (F). The essential changes in the patterns of the fatty acid methyl esters (FAMEs) for the polluted soil included an increase in the fatty acid saturation and hydroxy fatty acid abundance. The obtained results also indicated that the introduction of CF600 into the soil contaminated with 4-CP and SB or P caused an increase in the functional diversity of the soil microorganisms. In contrast, in the soil that had been inoculated with KB2 and in the non-inoculated soil, the addition of 4-CP and P decreased the microbial activity. In conclusion, the inoculation of both strains into contaminated soil with aromatic compounds caused irreversible changes in the functional and structural diversity of the soil microbial communities.

Effects of Pulp and Na-Bentonite Amendments on the Mobility of Trace Elements, Soil Enzymes Activity and Microbial Parameters under Ex Situ Aided Phytostabilization.

The objective of this study was to explore the potential use of pulp (by-product) from coffee processing and Na-bentonite (commercial product) for minimizing the environmental risk of Zn, Pb and Cd in soil collected from a former mine and zinc-lead smelter. The effects of soil amendments on the physicochemical properties of soil, the structural and functional diversity of the soil microbiome as well as soil enzymes were investigated. Moreover, biomass of Festuca arundinacea Schreb. (cultivar Asterix) and the uptake of trace elements in plant tissues were studied. The outdoor pot set contained the following soils: control soil (initial), untreated soil (without additives) with grass cultivation and soils treated (with additives) with and without plant development. All of the selected parameters were measured at the beginning of the experiment (t0), after 2 months of chemical stabilization (t2) and at the end of the aided phytostabilization process (t14). The obtained results indicated that both amendments efficiently immobilized the bioavailable fractions of Zn (87-91%) and Cd (70-83%) at t14; however, they were characterized by a lower ability to bind Pb (33-50%). Pulp and Na-bentonite drastically increased the activity of dehydrogenase (70- and 12-fold, respectively) at t14, while the activities of urease, acid and alkaline phosphatases differed significantly depending on the type of material that was added into the soil. Generally, the activities of these enzymes increased; however, the increase was greater for pulp (3.5-6-fold) than for the Na-bentonite treatment (1.3-2.2-fold) as compared to the control. Soil additives significantly influenced the composition and dynamics of the soil microbial biomass over the experiment. At the end, the contribution of microbial groups could be ordered as follows: gram negative bacteria, fungi, gram positive bacteria, actinomycetes regardless of the type of soil enrichment. Conversely, the shift in the functional diversity of the microorganisms in the treated soils mainly resulted from plant cultivation. Meanwhile, the highest biomass of plants at t14 was collected from the soil with Na-bentonite (6.7 g dw-1), while it was much lower in a case of pulp treatment (1.43-1.57 g dw-1). Moreover, the measurements of the heavy metal concentrations in the plant roots and shoots clearly indicated that the plants mainly accumulated metals in the roots but that the accumulation of individual metals depended on the soil additives. The efficiency of the accumulation of Pb, Cd and Zn by the roots was determined to be 124, 100 and 26% higher in the soil that was enriched with Na-bentonite in comparison with the soil that was amended with pulp, respectively. The values of the soil indices (soil fertility, soil quality and soil alteration) confirmed the better improvement of soil functioning after its enrichment with the pulp than in the presence of Na-bentonite.

Bioaugmentation as a strategy for the remediation of pesticide-polluted soil: A review.

Bioaugmentation, a green technology, is defined as the improvement of the degradative capacity of contaminated areas by introducing specific microorganisms, has emerged as the most advantageous method for cleaning-up soil contaminated with pesticides. The present review discusses the selection of pesticide-utilising microorganisms from various sources, their potential for the degradation of pesticides from different chemical classes in liquid media as well as soil-related case studies in a laboratory, a greenhouse and field conditions. The paper is focused on the microbial degradation of the most common pesticides that have been used for many years such as organochlorinated and organophosphorus pesticides, triazines, pyrethroids, carbamate, chloroacetamide, benzimidazole and derivatives of phenoxyacetic acid. Special attention is paid to bacterial strains from the genera Alcaligenes, Arthrobacter, Bacillus, Brucella, Burkholderia, Catellibacterium, Pichia, Pseudomonas, Rhodococcus, Serratia, Sphingomonas, Stenotrophomonas, Streptomyces and Verticillum, which have potential applications in the bioremediation of pesticide-contaminated soils using bioaugmentation technology. Since many factors strongly influence the success of bioaugmentation, selected abiotic and biotic factors such as pH, temperature, type of soil, pesticide concentration, content of water and organic matter, additional carbon and nitrogen sources, inoculum size, interactions between the introduced strains and autochthonous microorganisms as well as the survival of inoculants were presented.

Changes in fatty acid composition of Stenotrophomonas maltophilia KB2 during co-metabolic degradation of monochlorophenols.

The changes in the cellular fatty acid composition of Stenotrophomonas maltophilia KB2 during co-metabolic degradation of monochlorophenols in the presence of phenol as well as its adaptive mechanisms to these compounds were studied. It was found that bacteria were capable of degrading 4-chlorophenol (4-CP) completely in the presence of phenol, while 2-chlorophenol (2-CP) and 3-chlorophenol (3-CP) they degraded partially. The analysis of the fatty acid profiles indicated that adaptive mechanisms of bacteria depended on earlier exposure to phenol, which isomer they degraded, and on incubation time. In bacteria unexposed to phenol the permeability and structure of their membranes could be modified through the increase of hydroxylated and cyclopropane fatty acids, and straight-chain and hydroxylated fatty acids under 2-CP, 3-CP and 4-CP exposure, respectively. In the exposed cells, regardless of the isomer they degraded, the most important changes were connected with the increase of the contribution of branched fatty acid on day 4 and the content of hydroxylated fatty acids on day 7. The changes, particularly in the proportion of branched fatty acids, could be a good indicator for assessing the progress of the degradation of monochlorophenols by S. maltophilia KB2. In comparison, in phenol-degrading cells the increase of cyclopropane and straight-chain fatty acid content was established. These findings indicated the degradative potential of the tested strain towards the co-metabolic degradation of persistent chlorophenols, and extended the current knowledge about the adaptive mechanisms of these bacteria to such chemicals.

Facilitation of Co-Metabolic Transformation and Degradation of Monochlorophenols by Pseudomonas sp. CF600 and Changes in Its Fatty Acid Composition.

In this study, co-metabolic degradation of monochlorophenols (2-CP, 3-CP, and 4-CP) by the Pseudomonas sp. CF600 strain in the presence of phenol, sodium benzoate, and 4-hydroxybenzoic acid as an additional carbon source as well as the survival of bacteria were investigated. Moreover, the changes in cellular fatty acid profiles of bacteria depending on co-metabolic conditions were analyzed. It was found that bacteria were capable of degrading 4-CP completely in the presence of phenol, and in the presence of all substrates, they degraded 2-CP and 3-CP partially. The highest 2-CP and 3-CP removal was observed in the presence of sodium benzoate. Bacteria exhibited three various dioxygenases depending on the type of growth substrate. It was also demonstrated that bacteria exposed to aromatic growth substrates earlier degraded monochlorophenols more effectively than unexposed cells. The analysis of fatty acid profiles of bacteria indicated the essential changes in their composition, involving alterations in fatty acid saturation, hydroxylation, and cyclopropane ring formation. The most significant change in bacteria exposed to sodium benzoate and degrading monochlophenols was the appearance of branched fatty acids. The knowledge from this study indicates that Pseudomonas sp. CF600 could be a suitable candidate for the bioaugmentation of environments contaminated with phenolic compounds.

Bioaugmentation as a strategy for cleaning up of soils contaminated with aromatic compounds.

The contamination of soil with aromatic compounds is of particular environmental concern as they exhibit carcinogenic and mutagenic properties. One of the methods of their removal from soil is bioaugmentation, defined as a technique for improvement of the degradative capacity of contaminated areas by introduction of specific competent strains or consortia of microorganisms. The efficiency of bioaugmentation is determined by many abiotic and biotic factors discussed in this paper. The first include chemical structure, concentration and availability of pollutants as well as physico-chemical properties of soil. In turn, among biotic factors the most important is the selection of proper microorganisms that can not only degrade contaminants but can also successfully compete with indigenous microflora. Several strategies are being developed to make augmentation a successful technology particularly in soils without degrading indigenous microorganisms. These approaches involve the use of genetically engineered microorganisms and gene bioaugmentation. The enhancement of bioaugmentation may be also achieved by delivering suitable microorganisms immobilized on various carriers or use of activated soil.

FAME profiles in Pseudomonas vesicularis during catechol and phenol degradation in the presence of glucose as an additional carbon source.

The aim of this study was to evaluate the impact of catechol and phenol added to culture media separately and with glucose as an additional, easily-degradable carbon source on fatty acid methyl ester (FAME) composition in Pseudomonas vesicularis. Simultaneously, the degradation rates of aromatic substrates used were investigated in single and binary substrate systems. Both catechol and phenol treatments caused changes in the distribution of tested groups of fatty acids. The most noticeable changes included an increase in degree of fatty acid saturation, the appearance of branched and disappearance of hydroxy fatty acids as compared to the control sample with glucose. Under catechol or phenol treatment sat/unsat ratio showed the values of 8.63 and 11.38, respectively, whereas in control cells it reached the value of 2.66. The high level of saturation comes from the high content of cyclopropane fatty acids in bacteria under exposure to aromatic substrates, regardless of the presence of glucose. In these treatments their content was more than 3-fold higher compared to the control. It has been demonstrated that glucose supplementation of culture media containing single aromatic substrate extended the degradation rates of catechol and phenol by P. vesicularis, caused an increase in number of cells but did not significantly change the fatty acid profiles in comparison with bacteria growing on catechol and phenol added to the media individually.

Whole cell-derived fatty acid profiles of Pseudomonas sp. JS150 during naphthalene degradation.

Changes in cellular fatty acid composition during naphthalene degradation, at the concentrations of 0.5 g l(-1) or 1.0 g l(-1), by Pseudomonas sp. JS150 were investigated. In response to naphthalene exposure an increase in saturated/unsaturated ratio was observed. Additionally, the dynamic changes involved alterations in the contents of hydroxy, cyclopropane and branched fatty acids. Among the classes of fatty acids tested the most noticeable changes in the abundance of cyclopropane fatty acids were observed. Since day 4 of incubation these fatty acids were not dectected in bacterial cells growing on naphthalene. In contrast, markedly increased in the percentage of hydroxy fatty acids over time was observed. However, the proportions of saturated straight-chain and branched fatty acids did not change such significantly.

Changes in fatty acid composition in Pseudomonas putida and Pseudomonas stutzeri during naphthalene degradation.

The effects of naphthalene on the whole cell-derived fatty acid composition of Pseudomonas putida and Pseudomonas stutzeri during naphthalene degradation were investigated. These strains differed in their abilities to degrade naphthalene and in 1,2-catechol dioxygenase activities. The cells of both strains reacted to the addition of naphthalene with an increase in the saturated/unsaturated ratio. The dynamic changes comprised also alterations in the percentage of hydroxy, cyclopropane and branched fatty acids. Upon the exposure of naphthalene, new fatty acids were detected.

Changes in whole cell-derived fatty acids induced by naphthalene in bacteria from genus Pseudomonas.

Fatty acid composition during naphthalene utilization was investigated in three strains of bacteria Pseudomonas vesicularis, Pseudomonas stutzeri and Pseudomonas sp. JS150 that expressed different naphthalene degradation abilities. All strains significantly changed their cellular fatty acid profiles as a response to naphthalene exposure. Since naphthalene was present in the medium P. stutzeri increased ratio of saturated/unsaturated fatty acids from 1.1 to 2.1 and Pseudomonas sp. JS150 from 7.5 to 12.0, respectively. In contrast, this ratio decreased from 2.1 to 1.1 in P. vesicularis under the same growth conditions. The changes comprised also alterations in the percentage of selected groups of fatty acids: iso and anteiso, hydroxy and cyclopropane fatty acids. Our results showed that naphthalene induced in tested strains different changes in fatty acids composition. It may suggest that in the presence of naphthalene microorganisms used different adaptive mechanisms to maintain the cells in appropriate physiological state.