Production of biosurfactant by locally isolated bacteria from petrochemical waste

Ten bacterial strains previously isolated from petrochemical wastes were selected for the screening of biosurfactant producer(s), via four different methods; (i) surface tension measurements, (ii) blood hemolysis test, (iii) drop-collapsing test, and (iv) bacterial adherence to hydrocarbon (BATH) test. Two isolates coded AB-Cr1 and ETL-Cr1 identified as Actinobacillus sp. and Aeromonas sp., respectively were chosen to be the best candidates for biosurfactant production. Biosurfactant productions by both isolates were found to be growth-associated in all conditions tested. Biosurfactant production in glucose/crude oil medium (7.18-8.26 g/L) was found similar to that observed in crude oil-free medium (6.33-8.76 g/L). The production of biosurfactant was also studied in a fermentor using isolate AB-Cr1, as a factor of temperature, initial glucose concentration, pH and initial nitrogen concentration. The highest production of 12.45 g/L was obtained with AB-Cr1 grown in medium (pH 7) supplemented with 25mM NH4NO3 as nitrogen source and 3mM glucose as carbon source, incubated at 37°C under non-pH controlled strategy. TLC and FTIR characterization of crude biosurfactant produced by both isolates in medium supplemented or not with crude oil indicated the presence of lipoprotein and non-aromatic glycolipid types of biosurfactant. GC-MS analysis of fatty acid metyl esters indicated the presence of pentadecanoic acid in crude biosurfactant from both isolates as well as octadecanoic and heptadecanoic acid in the biosurfactant produced by AB-Cr1 and ETL-Cr1, respectively. The CMC of the biosurfactant produced in the presence and absence of crude oil were approximately (g/L) 1.0 and 0.1 for ABCr1, and 1.2 and 0.2 for ETL-Cr1, respectively. The biosurfactants were found capable of producing a relatively stable emulsion with hydrocarbon at pH 10. It was also found stable at various pHs (3.0-13.0 and 5.0-9.0) for AB-Cr1 and ETL-Cr1, respectively and thermostable for 1 hour at 100°C, based on the value of surface tensio

Ionic behavior assessment of surface-active compounds from corn steep liquor by exchange resins

Depending on their ionic nature, biosurfactants can be classified as nonionic, anionic, cationic, or amphoteric. The ionic behavior of biosurfactants is an important characteristic that dictates their use in industrial applications. In this work, a biosurfactant extract obtained from corn steep liquor was subjected to anionic or cationic resins, in order to study the ionic behavior under different operational conditions using response surface methodology. The independent variables included in the study are the dilution of biosurfactant solution, the amount of cationic or anionic resin, and the extraction time, whereas the dependent variables studied consisted of the surface tension of biosurfactant aqueous solution, after contacting with anionic or cationic resin. The results showed that biosurfactant extracted from corn steep liquor is amphoteric, since both resins were able to entrap this biosurfactant, making it particularly suited for use in personal care preparations for sensitive skin.Peer ReviewedPostprint (author's final draft

Production of lipopeptide biosurfactant by Kurthia gibsonii KH2 and their synergistic action in biodecolourisation of textile wastewater

Textile dyes are recalcitrant molecules and contain a high level of chemicals and colour which poses a serious challenge to surrounding environments. Therefore, this study aims to produce biosurfactant and investigate the synergistic action on decolourisation of textile dyes by the combination of bacteria and biosurfactant. An effective dye degrading strain and biosurfactant-producer, Kurthia gibsonii KH2, was isolated from textile wastewater using molasses as the only source of carbon and energy. The isolates were identified and screened for biosurfactant production using haemolytic activity, oil spreading technique, drop collapse test and emulsification index. Fourier Transform Infrared Spectrum (FTIR) and Thin Layer Chromatography (TLC) analyses were carried out to detect the type of biosurfactant. The effect of different physicochemical parameters on textile wastewater decolourisation was assessed within 24 h. The Kurthia gibsonii KH2 showed positive results for haemolytic activity, oil spreading technique, and drop collapse test. The emulsification test (E24) revealed that Kurthia gibsonii KH2 had a higher emulsification index of 63%. FTIR and TLC analyses indicated that the biosurfactant was a lipopeptide and was formed with a yield of 2 gL−1. The synergistic activity of Kurthia gibsonii KH2 and lipopeptide biosurfactant resulted in decolourisation levels of 85% at 100 mg/L concentration and pH 7 was recorded at 168 h of incubation. The high attributes of these combinations and the phytotoxicity tests implied that the metabolites were less toxic, making it a promising option for the biodecolourisation and biodegradation of industrial textile wastewater and various environmental conditions

Strategies for administration of biosurfactants-producing pseudomonads in closed hydroponic systems

Zoospore-producing oomycetes are major plant pathogens of particular concern in hydroponic systems. Compared with pesticides, biocontrol using antagonistic microorganisms is a sustainable approach to control oomycetes. Previous research has demonstrated that biosurfactants and biosurfactant-producing microorganisms are potentially useful components of a sustainable biocontrol strategy. In this study three ways of supplying a biosurfactant-producing strain to a recirculating hydroponic cultivation system infected with a zoospore-producing plant pathogen were evaluated. The strain P. koreensis 2.74 was added as washed cells, in its spent KB broth or in a minimal medium adapted from the nutrient solution, and compared with control treatments. A significant reduction in disease with up to 50% was achieved when a high concentration of washed cells was added weekly to the plant cultivation system. The disease suppression obtained through addition of washed cells equalled the effect achieved when the purified biosurfactant was used. Phytotoxicity was observed when the spent broth was included in the treatment

"In vitro" evaluation of some properties in spore former bacteria isolated from calves faeces

Aims: To isolate and evaluate spore-former bacteria for being used as probiotic additives in animal nutrition by their technological features. Study Design: The study was experimental, by using calves’ faeces for spore-forming identification and further evaluation of their “in vitro” probiotic-related properties. Place and Duration of Study: Laboratory of Preventive Microbiology, Centro de Referencia para Lactobacilos (CERELA-CONICET), between June 2013 and November 2013. Methodology: In this work, some Bacillus strains were isolated from calves’ faeces and evaluated for their “in vitro” beneficial characteristics: Surface properties, biosurfactant and emulsification production, and inhibition of pathogens. The antibiotic sensibility was also assayed. Results: Two Bacillus strains were selected, identified by phenotypic and molecular techniques as Bacillus subtilis strains M14 and M12. Spores resulted to be more hydrophobic than vegetative cells. The M14 strain showed biosurfactant and emulsifying properties. Inhibition assays against pathogenic bacteria indicated they inhibit gram-positive microorganisms. The antibiotic susceptibility showed that the two strains were sensitive to the antibiotics assayed, except Bacillus M12 that was resistant to Kanamycin. Conclusion: The results indicate these strains can be further studied for their inclusion in the design of a probiotic product for newborn calves.Fil: Maldonado, Natalia Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Silva de Ruíz, Clara. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; ArgentinaFil: Nader, Maria Elena Fatima. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentin

Increased Biological Activity of Aneurinibacillus migulanus Strains Correlates with the Production of New Gramicidin Secondary Metabolites

Acknowledgments This project was funded by the Government of Kuwait (to FA) and the European Union Seventh Framework Programme under grant agreement 245268 (ISEFOR; to LB and SW). Further support came from the SwissBOL project, financed by the Swiss Federal Office for the Environment (grant holder LB) and the Sciex–Scientific Exchange Programme (http://nms.ch/) (NMS.CH; to LL and LB). LL is indebted to the Ministry of Education, Science, Research and Sport of the Slovak Republic for financial support in the frame of the project “VEGA 1/0061/16” and “VEGA 1/0046/16”. Funding This project was funded by the Government of Kuwait (to FA) and the European Union Seventh Framework Programme under grant agreement 245268 (ISEFOR; to LB and SW). Further support came from the SwissBOL project, financed by the Swiss Federal Office for the Environment (grant holder LB) and the Sciex–Scientific Exchange Programme NMS.CH (to LL and LB). LL is indebted to the Ministry of Education, Science, Research and Sport of the Slovak Republic for financial support in the frame of the project “VEGA 1/0061/16.”Peer reviewedPublisher PD

Root uptake of lipophilic zinc-rhamnolipid complexes

This study investigated the formation and plant uptake of lipophilic metal-rhamnolipid complexes. Monorhamnosyl and dirhamnosyl rhamnolipids formed lipophilic complexes with copper (Cu), manganese (Mn), and zinc (Zn). Rhamnolipids significantly increased Zn absorption by Brassica napus var. Pinnacle roots in 65Zn-spiked ice-cold solutions, compared with ZnSO4 alone. Therefore, rhamnolipid appeared to facilitate Zn absorption via a nonmetabolically mediated pathway. Synchrotron XRF and XAS showed that Zn was present in roots as Zn-phytate-like compounds when roots were treated with Zn-free solutions, ZnSO4, or Zn-EDTA. With rhamnolipid application, Zn was predominantly found in roots as the Zn-rhamnolipid complex. When applied to a calcareous soil, rhamnolipids increased dry matter production and Zn concentrations in durum (Triticum durum L. cv. Balcali-2000) and bread wheat (Triticum aestivum L. cv. BDME-10) shoots. Rhamnolipids either increased total plant uptake of Zn from the soil or increased Zn translocation by reducing the prevalence of insoluble Zn-phytate-like compounds in roots