Katarzyna Paraszkiewicz

Emulsifier production by steroid transforming filamentous fungus Curvularia lunata. Growth and product characterization

Curvularia lunata IM 2901, the filamentous fungus used for hydrocortisone manufacture, was found to be able to produce an extracellular emulsifying agent on water-soluble compounds with a yield of 2.6 g l(-1). Cell-free culture broth containing the examined agent caused the formation of stable emulsions with hydrophobic compounds of natural and xenobiotic origin. Vegetable and mineral oils were the best substrates for emulsification. Kinetics of surfactant biosynthesis was classified as a mixed growth-associated and non-growth-associated type. The crude emulsifier was isolated from culture fluid by acetone precipitation. Preliminary chemical characterization showed that the studied bioemulsifier contained 34.0% C, 5.7% H, 1.8% N, 0.15% S and was a complex of protein (25%) and polysaccharide (48%). Sugar component was identified as a polymer of D-glucose.

Cortexolone 11β-hydroxylation in protoplasts of Curvularia lunata

Abstract Transformation of cortexolone to hydrocortisone by the filamentous fungus Curvularia lunata using protoplasts as a research tool was studied. A stable mutant of C. lunata (IM 2901/366) hydroxylated cortexolone at 11 β -position with significantly higher activity than the wild strain (IM 2901) at the similar rate of growth. Protoplasts released from the mycelium of the wild strain and the mutant transformed the steroid substrate with about four and over five times higher yield than the parental mycelium (respectively). Due to the higher hydroxylation ability of the mutant, the activity of mutant protoplasts was 24 times higher than the activity of the mycelium of the wild strain. Hydroxylation of cortexolone was blocked in both strains by the inhibitor of cytochrome P-450 (cyt P-450) activity, ketoconazole. Cyt P-450, as hemoprotein involved in steroid-hydroxylating system, was localized in microsomal fractions of both strains. Estimation of cyt P-450 content in the intact protoplasts revealed that the level of cyt P-450 in the mutant cells was higher and it increased more rapidly in steroid presence than in the wild strain cells. It is suggested that the higher amount of cyt P-450 and higher steroid transformation activity of the mutant result from mutation(s) of genes involved in steroid 11 β -hydroxylase synthesis regulation.

Malachite green decolorization by the filamentous fungus Myrothecium roridum--Mechanistic study and process optimization.

The filamentous fungus Myrothecium roridum isolated from a dye-contaminated area was investigated in terms of its use for the treatment of Malachite green (MG). The mechanisms involved in this process were established. Peroxidases and cytochrome P-450 do not mediate MG elimination. The laccase of M. roridum IM 6482 was found to be responsible for the decolorization of 8-11% of MG. Thermostable low-molecular-weight factors (LMWF) resistant to sodium azide were found to be largely involved in dye decomposition. In addition, MG decolorization by M. roridum IM 6482 occurred in a non-toxic manner. Data from antimicrobial tests showed that MG toxicity decreased after decolorization. To optimize the MG decolorization process, the effects of operational parameters (such as the medium pH and composition, process temperature and culture agitation) were examined. The results demonstrate that M. roridum IM 6482 may be used effectively as an alternative to traditional decolorization agents.

Detection of biosurfactants in Bacillus species: genes and products identification.

To screen environmental Bacillus strains for detection of genes encoding the enzymes involved in biosurfactant synthesis and to evaluate their products e.g. surfactin, iturin and fengycin.

Lipid composition in a strain of Bacillus subtilis, a producer of iturin A lipopeptides that are active against uropathogenic bacteria

Urinary tract infections are a common disease in humans. Therefore, new methods are needed to destroy biofilms that are formed by uropathogens. Iturin A lipopeptides (LPs) C14 and C15 are potent biosurfactants synthetized by the Bacillus subtilis I′1a strain. The biological activity of extracted LPs was confirmed by examining extracts from I′1a cultures against uropathogenic bacteria that had been isolated from biofilms on urinary catheters. Compared with cultures of DSM 3257, which produce surfactin at a relatively low level, the extract obtained from strain I′1a exhibited a greater inhibitory effect against both planktonic and sessile forms of Escherichia coli, Serratia marcescens, Enterobacter cloacae, Proteus mirabilis, Citrobacter freundii and Enterococcus faecalis. Moreover, cyclic LP biosurfactants may disturb the integrity of cytoplasmic membranes; therefore, we investigated the effects of synthetized LPs on fatty acids and phospholipids of B. subtilis. LPs and lipids were analyzed using GC–MS, LC–MS/MS and MALDI-TOF/TOF techniques. Compared with B. subtilis DSM 3257, membranes of the I′1a strain were characterized by an increased amount of anteiso fatty acids and a ten-fold higher ratio of phosphatidylglycerol (PG)-to-phosphatidylethanolamine (PE). Interestingly, in cultures of B. subtilis DSM 3257 supplemented with LP extracts of the I′1a strain, the PG-to-PE ratio was fourfold higher, and the amount of anteiso fatty acids was also increased.Graphical Abstract

Malachite green removal from aqueous solution using the system rapeseed press cake and fungus Myrothecium roridum

AbstractThe waste of rapeseed press cake (WRPC), obtained after the preparation of microbial culture medium, was investigated in a batch system as an adsorbent of malachite green (MG). The effects of the contact time, the temperature, the initial dye concentration and the adsorbent dosage were examined using MG aqueous solutions of pH 6.5. The highest sorption of MG was observed after 180 min in solution containing 50 mg/L of MG and 2.5 mg/L of WRPC. Equilibrium isotherm data was described by the Langmuir, Freundlich and Dubinin-Radushkevich models. The Langmuir expression was found to provide the best correlation. Kinetic models and thermodynamic parameters (Gibbs free energy, enthalpy, and entropy) were also investigated. Experimental data revealed that MG sorption followed the pseudo-second-order rate kinetics. MG desorption efficiency (94.5%) from WRPC with the use of 0.1 M NaOH solution was determined. Biological degradation of the dye-loaded sorbent in a submerged culture of the filamentous fungus M...

Synthesis of silver nanoparticles by Bacillus subtilis T-1 growing on agro-industrial wastes and producing biosurfactant.

In this study, culture supernatnats of Bacillus subtilis T-1 growing on brewery effluents and molasses was used for silver nanoparticles (Ag-NPs) synthesis. The biosurfactant production of B. subtilis T-1 was confirmed by the detection of genes in the genome and by the identification of the product in the supernatants. The genes for synthesis of surfactin (sfp, srfAA) and iturin (ituC) were noted by PCR reactions. Also, in examined culture supernatants the presence of C13, C14 and C15 surfactin homologues with the sodiated molecules [M + Na](+) at m/z 1030, 1044 and 1058 was confirmed using LC/MS/MS analysis. The formation of NPs in the culture supernatants was confirmed by UV-vis spectroscopy. The dynamic light scattering measurements and transmission electron microscopy images showed the nanometric sizes of the biosynthesised Ag-NPs which ranged from several nm to several tens of nm depending on the used culture supernatant. Biological properties of Ag-NPs were evaluated by binding of Ag-NPs with DNA isolated from the Escherichia coli ATCC 25922 and B. subtilis ATCC 6633. Biogenic Ag-NPs were actively bound to DNA in increased concentration which could be the one important mode of antibacterial action of the Ag-NPs.

Silver nanoparticles formed in bio- and chemical syntheses with biosurfactant as the stabilizing agent

ABSTRACT In this work, the comparison of the physical properties of silver nanoparticles (AgNPs) obtained via the reduction of silver nitrate (AgNO3) in biological and chemical (model) syntheses supplemented with the biosurfactant surfactin is described. In the studies, two strains of Bacillus subtilis (denoted T’1 and I’1a) were used. The biological synthesis of AgNPs was performed using supernatants obtained from cultures of bacteria growing on brewery effluents, molasses, and Luria–Bretani (LB) medium. In model experiments, ascorbic acid served as the reductant; surfactin acted as the stabilizing agent. The surfactin concentrations were adjusted to 5 and 30 mg/L, which corresponded to minimum and maximum surfactin concentrations as measured in the supernatants obtained from the B. subtilis cultures. The chemical synthesis was carried out at acidic as well as alkaline pH. Dynamic light scattering (DLS) revealed that in model and biological samples, single AgNPs were accompanied by aggregated structures. Transmission electron microscopy showed that the contribution of the aggregates in bacterial supernatants and in chemical synthesis is negligible under acidic conditions. However, in the alkaline environment, this contribution predominates. In the model experiments, smaller nanoparticles were formed with higher concentrations of surfactant. The presence of surfactin significantly increased the stability of AgNPs in both bio- and chemical syntheses. GRAPHICAL ABSTRACT

Application of Fungal Waste Biomass Originating from Steroid Hormone Manufacture for Heavy Metals Removal

Application of Fungal Waste Biomass Originating from Steroid Hormone Manufacture for Heavy Metals Removal The biomass of Curvularia lunata, used previously for hydrocortisone production, was investigated as a heavy metal biosorbent. Removal of lead, zinc and cadmium ions was evaluated as a function of biosorbent dosages, initial ion concentrations, mode of mycelium modifications, initial pH of metal solutions and when these metals ions where presented in binary as well in ternary combinations. The results presented in this paper indicate the potential utility of C. lunata waste biomass for lead and, to a lower extent, for zinc and cadmium ions removal from acid solutions.

Microbial Decolorization of Triphenylmethane Dyes

Synthetic dyes belong to important class of organic compounds extensively used in textile, paper printing, color photography, leather, plastics, food, cosmetic, and pharmaceutical industries (Ali, Water Air Soil Poll 213:251–273, 2010; Rauf and Ashraf, Chem Eng J 209:520–530, 2012). According to Global Industry Analysts, the production of worldwide synthetic dyes and pigments industries is predicted to reach almost 10 million tons by 2017 which will be worth close to