Bacterial Adhesion To Hydrocarbons Research Articles

Unveiling the Antibiotic Susceptibility and Antimicrobial Potential of Bacteria from Human Breast Milk of Pakistani Women: An Exploratory Study.

Human life quality and expectancy have increased dramatically over the past 5 decades because of improvements in nutrition and antibiotic's usage fighting against infectious diseases. Yet, it was soon revealed that the microbes adapted to develop resistance to any of the drugs that were used. Recently, there is great concern that commensal bacteria from food and the gastrointestinal tract of humans and animals could act as a reservoir for antibiotic resistance genes. Methodology. This study was intended for evaluating the phenotypic antibiotic resistance/sensitivity profiles of probiotic bacteria from human breast milk and evaluating the inhibitory effect of the probiotic bacteria against both Gram-negative and Gram-positive bacteria. The results point out that some of the isolated bacteria were resistant to diverse antibiotics including gentamycin, imipenem, trimethoprim sulfamethoxazole, and nalidixic acid. Susceptibility profile to certain antibiotics like vancomycin, tetracycline, ofloxacin, chloramphenicol, streptomycin, rifampicin, and bacitracin was also observed. The antimicrobial qualities of cell-free supernatants of some probiotic bacteria inhibited the growth of indicator bacteria. Also, antimicrobial properties of the probiotic bacteria from the present study attributed to the production of organic acid, bacterial adhesion to hydrocarbons (BATH), salt aggregation, coaggregation with pathogens, and bacteriocin production. Some isolated bacteria from human milk displayed higher hydrophobicity in addition to intrinsic probiotic properties like Gram-positive classification, catalase-negative activity, resistance to gastric juice (pH 2), and bile salt (0.3%) concentration. This study has added to the data of the antibiotic and antimicrobial activity of some probiotic bacteria from some samples of Pakistani women breast milk. Probiotic bacteria are usually considered to decrease gastrointestinal tract diseases by adhering to the gut epithelial and reducing population of pathogens and in the case of Streptococcus lactarius MB622 and Streptococcus salivarius MB620 in terms of hydrophobicity and exclusion of indicator pathogenic strains.

Assessment of the biofilm-forming ability on solid surfaces of periprosthetic infection-associated pathogens

Biofilm formation is one of the leading causes of complications after surgery in clinical settings. In this study, we profiled the biofilm-forming ability of various periprosthetic infection-associated pathogens on medically relevant surfaces, polystyrene (PS) and titanium (Ti). We also explored how a specific environmental stressor, epigallocatechin gallate (EGCG), affected biofilm formation. First, Congo red tests revealed that all microorganisms formed biofilms within 72 h. Then, the amounts of biofilm formation on PS at 24, 48 and 72 h and also on a Ti plate for 72 h were determined. Some microbes preferred one surface over the other, whereas other microbes formed consistent levels of biofilm regardless of the surface material. Staphylococcus lugdunenensis was the most potent, while Enterococcus faecalis and Staphylococcus aureus were the weakest. Bacterial adhesion to hydrocarbon (BATH) tests indicated that the biofilm-forming abilities were not directly correlated with cell surface hydrophobicity (CSH). Finally, an external signal, EGCG, was applied to challenge the biofilm formation of each microorganism. EGCG regulated each microorganism’s ability differently, though the change was consistent across surfaces for most pathogens. This study can help a better understanding of a broad spectrum of periprosthetic infection-associated pathogens by relative comparison of their biofilm-forming abilities.

Isolation and chemical characterization of the biosurfactant produced by Gordonia sp. IITR100.

Biosurfactants are amphipathic molecules produced from microorganisms. There are relatively few species known where the detailed chemical characterization of biosurfactant has been reported. Here, we report isolation and chemical characterization of the biosurfactant produced by a biodesulfurizing bacterium Gordonia sp. IITR100. Biosurfactant production was determined by performing oil spreading, drop-collapse, Emulsion index (E24), and Bacterial adhesion to hydrocarbons (BATH) assay. The biosurfactant was identified as a glycolipid by LCMS and GCMS analysis. The chemical structure was further confirmed by performing FTIR and NMR of the extracted biosurfactant. The emulsion formed by the biosurfactant was found to be stable between temperatures of 4°C to 30°C, pH of 6 to 10 and salt concentrations up to 2%. It was successful in reducing the surface tension of the aqueous media from 61.06 mN/m to 36.82 mN/m. The biosurfactant produced can be used in petroleum, detergents, soaps, the food and beverage industry and the healthcare industry.

Gastrointestinal transit tolerance, cell surface hydrophobicity, and functional attributes of Lactobacillus Acidophilus strains isolated from Indigenous Dahi.

Strains of Lactobacillus acidophilus WFA1 (KU877440), WFA2 (KU877441), and WFA3 (KU877442) were isolated from indigenous Dahi (yogurt), screened, and selected based on acid and bile tolerance along with the antimicrobial activity. These selected strains were further assessed for their probiotic and functional attributes. Results for simulated gastric and intestinal tolerance/ resistance revealed that all three strains can resist and survive under the following mentioned conditions. To access cell surface hydrophobicity, bacterial adhesion to hydrocarbons (BATH), cellular auto‐aggregation, and salt aggregation were performed. In BATH, adhesion of strains against three hydrocarbons namely xylene, dichloromethane, and hexadecane was conducted. The results show that strains showed the least adhesion to xylene (54.25%) as compared to dichloromethane (55.25%) and hexadecane (56.65%). WFA1 showed maximum adherence percentage (55.48%) followed WFA2 (55.48%) and WFA3 (51.38%). Cellular auto‐aggregation varied from 21.72% to 30.73% for WFA3 and WFA1, respectively. In the salt aggregation test (SAT), WFA1, WFA2, and WFA3 aggregated at 0.6, 1.0, and 2.0 molar concentrations of ammonium sulfate, respectively. PCR amplification of bile salt hydrolase gene (bsh) was performed and sequences were submitted to the public database of NCBI and Gene bank under accession numbers, KY689139, KY689140, and KY689141. Additionally, a cholesterol‐lowering assay was conducted and up to 26% reduction in cholesterol was observed by the strains. Regarding functional properties, exopolysaccharide (EPS) production, and antioxidant potential, strain WFA1 showed promising results EPS (1.027mg/ml), DPPH (80.66%), ABTS (81.97%), and reducing power (1.787). It can be concluded from the present study that the mentioned strains of L. acidophilus (WFA1, WFA2, and WFA3) are strongly hydrophobic; thus having an ability to survive and colonize under the gastrointestinal tract which confirms their probiotic nature. Regarding their functional properties, L. acidophilus WFA1 (KU877440) showed excellent properties of antioxidants and EPS production.

Studies on antibacterial and chemotaxis properties of Pseudomonas aeruginosa TEN01 biomass-derived sustainable biosurfactant

Biosurfactant producing bacterial strains were isolated from oil-contaminated sites at Chennai Petroleum Corporation Limited, Chennai, the potential strain was selected and identified as Pseudomonas aeruginosa TEN01 by 16 S rRNA sequencing technique. Biosurfactant was produced from cassava solid waste from the sago industry. Further, it was extracted by solvent extraction and partially purified by column chromatography. The partially purified biosurfactant was qualitatively analyzed by Thin Layer Chromatography (TLC), quantitatively analyzed by anthrone assay and characterized by Fourier Transform Infra-Red Spectroscopy (FT-IR) and Gas Chromatography-Mass Spectrometry (GC-MS). Rf value and chemical groups confirm the presence of glycolipid in the partially purified biosurfactant. GC-MS results confirmed the presence of long-chain fatty acids and carbohydrate which is found to be mainly present in glycolipids. Biosurfactants are surface-active molecules which have been found to be the best alternative to chemical-based surfactants. The present study focuses on modifying the cell surface using a biosurfactant from P. aeruginosa TEN01 to enhance membrane permeabilization. Antibacterial and chemotaxis properties of biosurfactant from P. aeruginosa TEN01 were found to be better towards Xenorhabdus poinarii, a bio-pesticide producing microbial strain, X. poinarii exhibited 81.7% adhesion to hydrocarbons upon biosurfactant treatment as analyzed by Bacterial Adhesion to Hydrocarbon (BATH) assay. The alteration in the membrane permeability was tested in X. poinarii using biosurfactant and chemical surfactants viz. Sodium dodecyl sulfate (SDS) and toluene by estimating the amount of intracellular protein released. High protein recovery (51.55%) was achieved with a biosurfactant. Cell viability in the biosurfactant-treated cells was also high (93.98%) in comparison to cells treated with chemical surfactants. Increased recovery of intracellular protein along with high cell viability makes the biosurfactant a potential candidate for application in numerous environmental fields.

Bioengineered Silver Nanoparticle from Spirulina platensis in Attenuating Biofilm Mediated Virulence in Vibrio parahemolyticus: An in vitro and in vivo Approach

Objectives: In this study, bioengineered AgNPs (silver nanoparticles) from Spirulina platensis was used to counter the biofilm mediated virulence by Vibrio parahemolyticus. Methods: AgNPs were synthesized from crude Spirulina platensis extract and characterized using UV spectrophotometry, Transmission electron microscope (TEM). Antibacterial effect against aquatic pathogen Vibrio parahemolyticus was carried out. Further, the nanoparticle at sub MIC (minimum inhibitory concentration) level were screened for anti-virulence property under in vitro studies which include biofilm inhibition using microtiter plate assay, microscopic analysis under light microscope and SEM (Scanning electron microscope) imaging, EPS (Exopolysaccharide) inhibition, CSH(Cell surface hydrophobicity) inhibition using BATH(Bacterial adhesion to hydrocarbons) assay, swarming and swimming motility inhibition, growth pattern analysis followed by in vivo study in aquatic animal model brine shrimp and its survival percentage along with light microscopic imaging was performed. Results: AgNPs, at 320μg/ml showed bactericidal activity, minimal inhibitory concentration was found to be 160 μg/ml. All anti-virulence assay performed at below sub MIC concentration. Biofilm and EPS showed 63% and 53% inhibition respectively, CSH was found to be decreased 3-fold. Growth pattern at sub MIC compared with non-treated showed similar result. In vivo study increased survival percentage (90%) when treated with AgNPs, compared to untreated (20%). A 7-fold increased resistance to pathogen was found and light microscope also confirms the efficacy of Ag nanoparticle. Conclusion: AgNPs become a substitute to the current commercial antibiotics used in aquaculture against Vibriosis, by functioning as an efficient quorum sensing inhibitor.

Production of Lipopeptide Biosurfactant by a Hydrocarbon-Degrading Antarctic Rhodococcus.

Rhodococci are renowned for their great metabolic repertoire partly because of their numerous putative pathways for large number of specialized metabolites such as biosurfactant. Screening and genome-based assessment for the capacity to produce surface-active molecules was conducted on Rhodococcus sp. ADL36, a diesel-degrading Antarctic bacterium. The strain showed a positive bacterial adhesion to hydrocarbon (BATH) assay, drop collapse test, oil displacement activity, microplate assay, maximal emulsification index at 45% and ability to reduce water surface tension to < 30 mN/m. The evaluation of the cell-free supernatant demonstrated its high stability across the temperature, pH and salinity gradient although no correlation was found between the surface and emulsification activity. Based on the positive relationship between the assessment of macromolecules content and infrared analysis, the extracted biosurfactant synthesized was classified as a lipopeptide. Prediction of the secondary metabolites in the non-ribosomal peptide synthetase (NRPS) clusters suggested the likelihood of the surface-active lipopeptide production in the strain’s genomic data. This is the third report of surface-active lipopeptide producers from this phylotype and the first from the polar region. The lipopeptide synthesized by ADL36 has the prospect to be an Antarctic remediation tool while furnishing a distinctive natural product for biotechnological application and research.

Biodegradation of heavy oily sludge by a two-step inoculation composting process using synergistic effect of indigenous isolated bacteria

The impact of two-step inoculation of indigenous strains and their synergistic effect in the scaling-up of petroleum hydrocarbons biodegradation from a mineral-based medium (MBM) to a two-phase composting process were investigated. After isolating the strains KA3 and KA4 from heavy oily sludge (HOS), their emulsification index (E24), bacterial adhesion to hydrocarbon (BATH), and oil degradation efficiency were evaluated in the MBM. Then, they were inoculated twice into the composting bioreactors lasted for the primary 8 weeks as the first phase (FP) and subsequent 8 weeks as the second phase (SP). The results indicated that the consortium of the two strains degraded 16-61% of crude oil (1-5% concentration) in the MBM. In the composting reactors, removals of 20 g kg−1 initial concentration of total petroleum hydrocarbons (TPH) were found to be 63.95, 61.00, and 89.35% for the strains KA3, KA4, and their consortium, respectively. The computed biodegradation constants indicated the synergistic effect of the two strains and the effectiveness of the second-step inoculation. The study demonstrated the successful scaling-up of HOS biodegradation from MBM to the two-phase composting process through two-step inoculation of the isolated strains.

Expansion of the Spore Surface Polysaccharide Layer in Bacillus subtilis by Deletion of Genes Encoding Glycosyltransferases and Glucose Modification Enzymes.

Polysaccharides (PS) decorate the surface of dormant endospores (spores). In the model organism for sporulation, Bacillus subtilis, the composition of the spore PS is not known in detail. Here, we have assessed how PS synthesis enzymes produced during the late stages of sporulation affect spore surface properties. Using four methods, bacterial adhesion to hydrocarbons (BATH) assays, India ink staining, transmission electron microscopy (TEM) with ruthenium red staining, and scanning electron microscopy (SEM), we characterized the contributions of four sporulation gene clusters, spsABCDEFGHIJKL, yfnHGF-yfnED, ytdA-ytcABC, and cgeAB-cgeCDE, on the morphology and properties of the crust, the outermost spore layer. Our results show that all mutations in the sps operon result in the production of spores that are more hydrophobic and lack a visible crust, presumably because of reduced PS deposition, while mutations in cgeD and the yfnH-D cluster noticeably expand the PS layer. In addition, yfnH-D mutant spores exhibit a crust with an unusual weblike morphology. The hydrophobic phenotype from sps mutant spores was partially rescued by a second mutation inactivating any gene in the yfnHGF operon. While spsI, yfnH, and ytdA are paralogous genes, all encoding glucose-1-phosphate nucleotidyltransferases, each paralog appears to contribute in a distinct manner to the spore PS. Our data are consistent with the possibility that each gene cluster is responsible for the production of its own respective deoxyhexose. In summary, we found that disruptions to the PS layer modify spore surface hydrophobicity and that there are multiple saccharide synthesis pathways involved in spore surface properties.IMPORTANCE Many bacteria are characterized by their ability to form highly resistant spores. The dormant spore state allows these species to survive even the harshest treatments with antimicrobial agents. Spore surface properties are particularly relevant because they influence spore dispersal in various habitats from natural to human-made environments. The spore surface in Bacillus subtilis (crust) is composed of a combination of proteins and polysaccharides. By inactivating the enzymes responsible for the synthesis of spore polysaccharides, we can assess how spore surface properties such as hydrophobicity are modulated by the addition of specific carbohydrates. Our findings indicate that several sporulation gene clusters are responsible for the assembly and allocation of surface polysaccharides. Similar mechanisms could be modulating the dispersal of infectious spore-forming bacteria.

Construction of potential bacterial consortia for efficient hydrocarbon degradation

Hydrocarbon-degrading bacteria were isolated from 2% hydrocarbon enriched sample collected from vehicular repairing stations, garages and petrol bunk. Incubation of the isolated non-virulent strains in Bushnell-Haas (BH) medium supplemented with hydrocarbon, showed their ability to survive on hydrocarbon thereby reducing the total organic carbon content. Based on the degradation potential, different bacterial consortia were prepared and consortium CHM1 was found to grow best with maximum degradation. 16S rRNA gene sequencing of the strains revealed their identity with Klebsiella spp., Enterobacter sp. and Pantoea sp. high to moderate affinity towards hydrocarbon of the selected strains were indicated by Bacterial Adhesion To Hydrocarbon (BATH) test and Contact Angle. Gas Chromatography-Mass Spectrometric (GC-MS) analysis of the mixed hydrocarbon containing broth revealed the presence of benzene derivatives, aliphatic acids, naphthalene, aliphatic alkanes, cyclic aliphatics as major compounds. The efficiency of the selected bacterial consortium showed an overall 16.20% degradation of the mixed hydrocarbon after 4 days, where, aliphatic cyclic compound (1-(1,5-Dimethylhexyl)-4-(4-Methylpentyl)-Cyclohexane) were completely degraded, naphthalene derivatives were reduced to 36.72%, aliphatic acids were degraded to 78.13% and benzene derivatives to 24.16%. Degradation of the long-chain aliphatic alkanes was further observed through Fourier Transform Infrared spectrometric (FTIR) analysis.

Biodegradation of high concentrations of petroleum compounds by using indigenous bacteria isolated from petroleum hydrocarbons-rich sludge: Effective scale-up from liquid medium to composting process

The scale-up of petroleum hydrocarbons-rich sludge (PHRS) bioremediation from liquid medium to a composting method bioaugmentated with two indigenous bacteria, capable of degrading high levels of crude oil, was surveyed. After isolating the strains (Sphingomonas olei strain KA1 and Acinetobacter radioresistens strain KA2) and determining their biomass production, emulsification index (E24), bacterial adhesion to hydrocarbon (BATH), and crude oil degradation in liquid medium, they were inoculated into the composting experiments. In liquid medium, the removal rate of crude oil were 67.25, 70.86, 61.77, 42.13, and 27.92%, respectively for the initial oil levels of 1, 2, 3, 4, and 5% after 7 days. Degradation of 10, 20, 30, 40 and 50 g kg−1 concentrations of total petroleum hydrocarbons (TPH) were also calculated to be 91.24, 87.23, 84.69, 74.08, and 60.14%, respectively after a composting duration of 12 weeks. The values of the rate constants (k) and half-lives (t1/2) of petroleum hydrocarbons degradation were 0.083–0.212 day−1 and 3.27–8.35 days for the first-order and 0.003–0.089 g kg−1day−1 and 1.12–6.67 days for the second-order model, respectively. This study verified the suitability of the isolated strains for PHRS bioremediation. Successful scale-up of PHRS bioremediation from a liquid medium to a composting process for degrading high amounts of TPH was also confirmed.

Biofilm and Biosurfactant Mediated Aromatic Hydrocarbons Degradation by Marine Bacteria Isolated from Contaminated Marine Environments of Niger Delta

Aims: To examine the effects of biofilm and biosurfactant associated cells of marine bacteria isolated from contaminated marine environments of Niger Delta on aromatic hydrocarbon degradation.&#x0D; Study Design: Nine treatments and the controls designs were set up in triplicates containing 100 mL of sterile modified mineral basal medium in 250 mL conical flasks supplemented with 50, 100, 200 and 300 ppm of xylene, anthracene and pyrene each and nine marine hydrocarbon degraders; incubated at 24°C for 5 - 7 days. The nine treatments and control set ups designated as ANT1, XYL2, PYR3, ANT4, PYR5, ANT6, XYL7, XYL8, PYR9 and CTRL (without hydrocarbons) were used to examine the effects of biofilm and biosurfactant produced by the marine bacteria on aromatic hydrocarbon degradability.&#x0D; Place and Duration of Study: Department of Microbiology, Chukwuemeka Odumegwu Ojukwu University, Uli Nigeria between September, 2014 and August, 2017.&#x0D; Methodology: A laboratory scale study was carried on six composite samples of the sediment and water samples from the three studied areas using enrichment, selection, morphological, biochemical, growth effect, emulsification, surface tension, bacterial adherence to hydrocarbon (BATH), salt aggregation (SAT) and microtitre plate biofilm formation tests.&#x0D; Results: The findings revealed that the three sampling sites harbour a lot of efficient aromatic degrading bacterial strains belonging to the genera: Providencia, Alcaligenes, Brevundimonas, Myroides, Serratia, and Bacillus able to significantly (P = .05) degrade the aromatic hydrocarbons. Significant positive correlation between biofilm formation and emulsification activity (r = 0.670; P = .05), was observed while surface tension (r = 0.134; P &gt; .05), BATH (r = 0.142; P &gt; .05) and SAT (r = 0.227; P &gt; .05) had no significant positive correlation with biofilm formation.&#x0D; Conclusion: Thus, the metabolic traits potentials of these strains could be exploited for in situ bioremediation intervention in the coastal areas of Nigeria.

Accurate prediction of anti-phagocytic activity of Vibrio vulnificus by measurement of bacterial adherence to hydrocarbonsPrediction of Anti-Phagocytic Activity.

Vibrio vulnificus can cause necrotizing soft tissue infection via exposure through an open wound, and the incubation period in cases of wound infection is only about 16h. These facts strongly suggest that mechanisms to evade innate immune cell phagocytosis are essential for its pathogenicity. Hydrophobic interaction is one of the binding mechanisms between bacteria and phagocytes. Several factors that maintain cell surface hydrophobicity (CSH) can contribute to anti-phagocytic activity. In this study, we tried to identify V.vulnificus genes involved in maintaining the CSH, in order to elucidate mechanisms of anti-phagocytic activity. We obtained 143 mutants that had lost their ability to proliferate in the host, using signature-tagged transposon basis mutagenesis (STM). The CSH of these mutants was measured by the bacterial adherence to hydrocarbons (BATH) assay. The CSH of only four mutants differed significantly from that of wild type (WT). Of these four mutants, degS mutant (degS::Tn) showed lesser anti-phagocytic activity than WT in the opsonophagocytosis assay, even though degS::Tn showed opaque-type colonies. Furthermore, survival times of mice subcutaneously inoculated with degS::Tn were prolonged. These facts indicated that the BATH assay is a more suitable method of analyzing the anti-phagocytic activity of V.vulnificus than the comparison of colony morphology.

Screening of cell surface properties of potential probiotic lactobacilli isolated from human milk.

Evaluation of eleven candidate probiotic Lactobacillus strains isolated from human milk showed that some of the strains were well endowed with desirable cell surface and attachment attributes. The cell surface properties (hydrophobicity, auto-aggregation, attachment to collagen and HT-29 monolayer) of probiotic Lactobacillus species of human milk origin were compared with reference probiotic/ non-probiotic species and pathogenic strains. The bacterial adhesion to hydrocarbons (BATH) was determined using three aliphatic (Chloroform, n-Hexane and n-Octane) and two aromatic (Toluene and Xylene) solvents. Maximum affinity of Lactobacillus strains towards chloroform and toluene indicated the presence of low electron acceptor/ acidic surface components on cell surface of most of the strains. The highest value of per cent hydrophobicity was recorded with chloroform in HM1 (L. casei) (97·10 ± 3·35%) and LGG (98·92 ± 1·24%). A moderate auto-aggregation attribute was observed in all of our Lactobacillus isolates. Only HM10, HM12 and HM13 exhibited comparatively enhanced precipitation rate after 7 h of incubation period. The adhesion potential to collagen matrix was highest in LGG (26·94 ± 5·83%), followed by HM1 (11·07 ± 3·54%) and HM9 (10·85 ± 1·74%) whereas, on HT-29 cells, HM8 (14·99 ± 3·61%), HM3 (13·73 ± 1·14%) and HM1 (11·21 ± 3·18%) could adhere effectively. In this manner, we noticed that although the cell surface properties and adhesion prospective of probiotic bacteria were strain dependent, five of our isolates viz. HM1, HM3, HM8, HM9 and HM10 exhibited promising cell surface properties, which could be further targeted as indigenous probiotic.

Characterization of extracellular virulence properties and biofilm-formation capacity of Vibrio species recovered from ready-to-eat (RTE) shrimps

In this study, we evaluated the virulence factor production, biofilm-forming ability and cell surface properties of ready-to-eat shrimps associated vibrios strains. A total of 1440 ready-to-eat (RTE) shrimp samples were purchased from open markets in southern Nigeria, from November 2016 to October 2017. Biofilm formation was carried out using the microtitre plate method. Cell-to-cell adhesion of Vibrio species was assessed via surface hydrophobicity using the bacterial adherence to hydrocarbons (BATH) and salting aggregation technique, autoaggregation and coaggregation assay. The virulence potential of the identified 120 Vibrio strains includes haemolysis 107 (89.17%), lipase 106 (88.33%), protease 108 (90%), gelatinase 111 (92.5%), the presence of surface-layer (S-layer) 109 (90.8%) and DNA degrading activity 107 (89.17%). Biofilm formation at 30 °C tryptone soy broth in dynamic conditions revealed total biofilm producers for the Vibrio species as follows: V. parahaemolyticus (95.65%), V. vulnificus (92.86%), V. fluvialis (91.67%), V. alginolyticus (87.5%), V. cholerae (100%), V. mimicus (90%), V. harveyi (66.7%), and other Vibrio spp. (84%). A total of 50 biofilm producing vibrios using BATH technique include 49 (98%) hydrophilic and 1 (2%) moderately hydrophobic. Using the modified salting aggregation technique, 50 (100%) was characterized as hydrophilic. Autoaggregation index for the 12 biofilms producing Vibrio strains ranged from 11.6 to 41.3%, while the autoaggregation index for the 12 test bacteria ranged from 26.2 to 71.3%. Coaggregation between the 12 test bacteria with the 12 Vibrio strains ranged from 9.3 to 78.5%. However most vibrios in this study were hydrophilic, their hydrophilic potential is important for their capability to autoaggregate and coaggregate. Findings on the specific process by which virulent Vibrio spp. form biofilm and adhere to shrimp surface as attached plankton may assist in monitoring epidemics of the pathogen.

Analysis of Biofilms Formation by Cronobacter sp. during Growth in Infant Formula Milk

Pacifier nipples are in permanent contact with saliva and with the oral microflora therefore, act as a favoured site for the growth of biofilms. This research was conducted to identify the bacterial biofilms that has been found on the pacifiers that collected from local child nursery and to analyse the formation of biofilms by Cronobacter sp. during growth in infant formula milk. Pacifiers collected were analysed to obtain colony forming unit (CFU) and isolated bacteria were identified using several biochemical tests according to Bergey’s Manual. Biofilm assay of three Cronobacter sp. were conducted using 24 wells microtiter plate and stained with 1% of crystal violet solution at different time interval: 6, 12, 18 and 24 h. The hydrophobicity of the bacterial cell suspension was evaluated using bacterial adhesion to hydrocarbons (BATH) method. Extracellular polymeric substances (EPS) analysis was done to identify percentage of carbohydrate and protein content by using phenol sulphuric acid method and Bradford method, respectively. The results obtained showed that the normal microflora bacteria were the most abundant microorganisms that were found on the pacifier with the main genus isolated was Staphylococcus sp., Enterobacteriaceae sp. and Clostridium sp. Based on biofilm and EPS analysis, Cronobacter sakazakii formed a strong biofilms after 18 h, with carbohydrate was identified as main component of EPS.

Invitro biofilm formation in ESBL producing Escherichia coli isolates from cage birds.

To determine biofilm and hydrophobicity formation ratios in extended spectrum beta lactamases (ESBL) synthesizing Escherichia coli isolates which were isolated from feces samples of 150 cage bird species randomly taken from pet shops in Hatay province, Turkey. Invitro biofilm production of 4 ESBL positive isolates were performed by Congo Red Agar (CRA), Standard Tube (ST) and Microtitre Plate (MP) methods while their hydrophobicity were examined by bacterial adhesion to hydrocarbon (BATH) test. In the examined isolates, while biofilm production was found to be negative by CRA method, highest biofilm producing strain, among 4 bacteria was determined to be A42 by ST and MP methods. The Scanning Electron Microscopy (SEM) also displayed these confirmed findings. The hydrophobicity values of strains were determined to be between 22.45% and 26.42%. As a result, biofilm formation in cage bird feces originated ESBL positive Escherichia coli isolates was performed for the first time in Turkey. In order to present the relation between pathogenicity and biofilm production in animal originated ESBL positive isolates, further studies are required.

Biosurfactant-mediated Biocontrol of Macrophomina phaseolina Causing Charcoal Rot in Vigna mungo by a Plant Growth Promoting Enterococcus sp. BS13

A potential bacterial isolate Enterococcus sp. BS13 screened from rhizospheric soil of Vigna mungo was identified as Enterococcus sp. based on morphological, biochemical and genomic characterization. The biosurfactant producing activity of BS13 was based on many tests such as blood heamolysis test, CTAB agar, emulsification stability (E24) test, oil spreading/displacement assay, drop collapse assay, bacterial adhesion to hydrocarbons (BATH) assay and surface tension (ST) measurement after 72 h of growth. GC-MS and FT-IR analyses established the similarity of biosurfactant with glycolipid type biosurfactant. Furthermore, Enterococcus sp. BS13 displayed plant growth-promoting ability, HCN production and antagonistic activity against Macrophomina phaseolina. Scanning electron microscopic study of fungal mycelia from zone of inhibition showed hyphal degradation, halo cell formation and mycelial deformities in the pathogen. M. phaseolina sclerotia formation and development were arrested towards the zone of interaction; consequently, such mycelia and sclerotia lost the vigour. In pot trials Enterococcus sp. BS13 increased the growth of V. mungo with considerable diseases reduction. Hence, Enterococcus sp.BS13 bears ability of biosurfactant production, plant growth promotion and biocontrol of M. phaseolina. Therefore, the exogenous application of BS13 can be a potential strategy to accelerate plant growth promotion and biocontrol of M. phaseolina.

Effect of low-concentration rhamnolipid on transport of Pseudomonas aeruginosa ATCC 9027 in an ideal porous medium with hydrophilic or hydrophobic surfaces

The success of effective bioaugmentation processes for remediation of soil and groundwater contamination requires effective transport of the injected microorganisms in the subsurface environment. In this study, the effect of low concentrations of monorhamnolipid biosurfactant solutions on transport of Pseudomonas aeruginosa in an ideal porous medium (glass beads) with hydrophilic or hydrophobic surfaces was investigated by conducting miscible-displacement experiments. Transport behavior was examined for both glucose-grown and hexadecane-grown cells, with low and high surface hydrophobicity, respectively. A clean-bed colloid deposition model was used for determination of deposition rate coefficients. Results show that cells with high surface hydrophobicity exhibit greater retention than cells with low surface hydrophobicity. Rhamnolipid affects cell transport primarily by changing cell surface hydrophobicity, with an additional minor effect by increasing solution ionic strength. There is a good linear relation between k and rhamnolipid-regulated cell surface hydrophobicity presented as bacterial-adhesion-to-hydrocarbon (BATH) rate of cells (R2=0.71). The results of this study show the importance of hydrophobic interaction for transport of bacterial cells in silica-based porous media, and the potential of using low-concentration rhamnolipid solutions for facilitating bacterial transport in bioaugmentation efforts.

Evaluating the Effect of Copper Nanoparticles in Inhibiting Pseudomonas aeruginosa and Listeria monocytogenes Biofilm Formation.

Background:Biofilm formation is a major virulence factor in different bacteria. Biofilms allow bacteria to resist treatment with antibacterial agents. The biofilm formation on glass and steel surfaces, which are extremely useful surfaces in food industries and medical devices, has always had an important role in the distribution and transmission of infectious diseases.Objectives:In this study, the effect of coating glass and steel surfaces by copper nanoparticles (CuNPs) in inhibiting the biofilm formation by Listeria monocytogenes and Pseudomonas aeruginosa was examined.Materials and Methods:The minimal inhibitory concentrations (MICs) of synthesized CuNPs were measured against L. monocytogenes and P. aeruginosa by using the broth-dilution method. The cell-surface hydrophobicity of the selected bacteria was assessed using the bacterial adhesion to hydrocarbon (BATH) method. Also, the effect of the CuNP-coated surfaces on the biofilm formation of the selected bacteria was calculated via the surface assay.Results:The MICs for the CuNPs according to the broth-dilution method were ≤ 16 mg/L for L. monocytogenes and ≤ 32 mg/L for P. aeruginosa. The hydrophobicity of P. aeruginosa and L. monocytogenes was calculated as 74% and 67%, respectively. The results for the surface assay showed a significant decrease in bacterial attachment and colonization on the CuNP-covered surfaces.Conclusions:Our data demonstrated that the CuNPs inhibited bacterial growth and that the CuNP-coated surfaces decreased the microbial count and the microbial biofilm formation. Such CuNP-coated surfaces can be used in medical devices and food industries, although further studies in order to measure their level of toxicity would be necessary.