Isolation and partial characterization of a biosurfactant produced by Streptococcus thermophilus A

Isolation and characterization of the surface active components from the crude biosurfactant produced by Streptococcus thermophilus A was studied. A fraction rich in glycolipids was obtained by the fractionation of crude biosurfactant using hydrophobic interaction chromatography. Molecular (by Fourier transform infrared spectroscopy) and elemental compositions (by X-ray photoelectron spectroscopy) were determined. Critical micelle concentration achieved was 20g/l, allowing for a surface tension value of 36mJ/m(2). Moreover, this glycolipid rich fraction was found to be an anti-adhesive and antimicrobial agent against several bacterial and yeast strains isolated from explanted voice prostheses. Further purification steps should be carefully analyzed as each purification step will increase the costs and decreases the amounts of biosurfactants recovered.     

Purification and characterization of a biosurfactant produced by Pseudomonas sp. G11 by asymmetrical flow field-flow fractionation (AsFlFFF)

Three hundred and thirty two bacterial colonies were isolated from soil contaminated by an oil spill. All the bacteria were cultured in a liquid medium individually, and the surface tensions of the media were compared. The bacterium whose culture medium had the lowest surface tension was identified as Pseudomonas sp. G11. A biosurfactant was produced by cultivation of the Pseudomonas sp. G11 in the LB media. For extraction of the biosurfactant, two solvent systems were used (n-hexane and a 2:1 (v/v) mixture of chloroform/MeOH), and the results were compared. Various experimental conditions (solvent composition, flow rate, etc.) were tested to optimize the analysis of the biosurfactant by asymmetrical flow field-flow fractionation (AsFlFFF). The biosurfactant was successfully separated from the culture medium by AsFlFFF when pure water was used as the carrier. From the retention data, the hydrodynamic diameter (d _H) and molecular weight (M) of the biosurfactant were determined by AsFlFFF. The molecular weight was determined by using pullulans as the calibration standards. The d _H and M were 49 nm and 2.3 × 10⁵ Da when extracted with n-hexane, and 39 nm and 1.13 × 10⁵ Da when extracted with the 2:1 mixture of chloroform/MeOH, respectively. Figure Separation of biosurfactant from its culture medium by flow FFF     

Physicochemical and functional characterization of a biosurfactant produced by Lactococcus lactis 53

Isolation and identification of key components of the crude biosurfactant produced by Lactococcus lactis 53 was studied. Fractionation was achieved by hydrophobic interaction chromatography which allowed the isolation of a fraction rich in glycoproteins. Molecular (by Fourier transform infrared spectroscopy) and elemental compositions (by X-ray photoelectron spectroscopy) were determined. Critical micelle concentration achieved for the isolated fraction was 14 g/l, allowing for a surface tension value of 36 mJ/m(2). Moreover, the isolated fraction, stable to pH changes between 5 and 9, was found to be an anti-adhesive and antimicrobial agent against several bacterial and yeast strains isolated from explanted voice prostheses, even at low concentrations. Further purification steps should be carefully analyzed as each purification step will increase the costs and decreases the amounts of biosurfactants recovered.     

Comparative study of biosurfactant produced by microorganisms isolated from formation water of petroleum reservoir

Biosurfactant produced by Pseudomonas aeruginosa, Bacillus subtilis and Rhodococcus erythropolis that isolated from the formation water of Chinese petroleum reservoir has been compared in surface abilities and oil recovery. Maximum biosurfactant production reached to about 2.66 g/l and the surface tension of liquid decreased from 71.2 to 22.56 mN/m using P. aeruginosa. Three strains exhibited a good ability to emulsify the crude oil, and biosurfactant of P. aeruginosa attained an emulsion index of 80% for crude oil which was greater than other strains. Stability studies were carried out under the extreme environmental conditions, such as high temperature, pH, salinity and metal ions. Results showed an excellent resistance of all biosurfactants to retain their surface-active properties at extreme conditions. It was found that the biosurfactants from three isolated bacteria showed a good stability above pH of 5, but at lower pH (from 1 to 5) they will harmfully be affected. They were able to support the condition up to 20 g/l salinity. P. aeruginosa biosurfactant was even stable at the higher salinity. Regarding temperature, all produced biosurfactants demonstrated a good stability in the temperature up to 120 °C. But stability of three biosurfactants was affected by monovalent and trivalent ions. Oil recovery experiments in physical simulation showed 7.2-14.3% recovery of residual oil after water flooding when the biosurfactant of three strains was added. These results suggest that biosurfactants of these indigenous isolated strains are appropriate candidates for enhanced oil recovery with a preference to biosurfactant of P. aeruginosa.     

Protease production by Streptomyces sp. isolated from brazilian cerrado soil

Streptomyces are important microorganisms because of their capacity to produce numerous bioactive molecules. In the present work protease production, by Streptomyces sp. 594 isolated from a Brazilian Cerrado soil, was maximized by optimizing a low-cost culture medium composition (casitone and sugarcane molasses) using statistical experimental design. The final protease activity (56 U/mL) was 2.8-fold and 58-fold higher than that obtained in the beginning of this study, and in a previous work, using an actinomycete selection medium, respectively. Protease production, not growth associated, appeared to be modulated by an inducer system, whereby the C/N ratio seemed to play a significant role.     

Isolation and partial characterization of an antifungal protein produced by Bacillus licheniformis BS-3

An antifungal protein produced by Bacillus licheniformis strain BS-3 was purified to homogeneity by ammonium sulfate precipitation, DEAE-52 column chromatography and Sephadex G-75 column chromatography. The purified protein was designated as F2 protein, inhibited the growth of Aspergillus niger, Magnaporthe oryzae and Rhizoctonia solani. F2 protein was a monomer with approximately molecular weight of 31 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gave a single peak on High Performance Liquid Chromatography (HPLC). Using Rhizoctonia solani as the indicator strain, the EC50 of F2 protein was 35.82 μg/mL, displaying a higher antifungal activity in a range of pH 6.0 to pH 10.0, and at a temperature below 70 °C for 30 min. F2 protein was moderately resistant to hydrolysis by trypsin, proteinase K, after which its relative activities were 41.7% and 59.5%, respectively. F2 protein was assayed using various substrates to determine the enzymatic activities, the results showed the hydrolyzing activity on casein, however, no enzymatic activities on colloidal chitin, CM-cellulose, xylan, M. lysodeikticus, and p-nitrophenyl-N-acetylglucosaminide.     

Chemical investigation of metabolites produced by an endophytic Aspergillus sp. isolated from Limonia acidissima

Endophytic fungi are considered as a good source to produce important secondary metabolites with interesting bioactivities. In a continuation of our studies towards the search for environmentally friendly bioactive compounds from Sri Lankan flora, we investigated the secondary metabolites produced by the endophytic fungi Aspergillus sp. isolated from the seeds of the popular edible fruit Limonia acidissima L. of the family Rutaceae. The pure culture of the Aspergillus sp. was grown on potato dextrose broth media. After 4 weeks fermentation, fungal media were extracted with organic solvents. Chromatographic separation of the fungal extracts over silica gel, Sephadex LH-20 and RP-HPLC furnished flavasperone (1), rubrofusarin B (2), aurasperone A (3), fonsecinone D (4) and aurasperone B (5). Compounds 1–4 showed moderate activities in brine shrimp toxicity assay. This is the first report of the ¹³C NMR data of compounds 4 and 5.     

Extraction and partial characterisation of antioxidant pigment produced by Chryseobacterium sp. kr6

Pigments synthesised by Chryseobacterium sp. kr6 growing on feather waste were extracted and characterised. The pigment extract was characterised by KOH test, UV–vis, CIELAB colour system, HPLC-DAD-MS, FTIR and its antioxidant capacity was evaluated. A positive bathochromic shift was observed when kr6 colonies or pigment extracts were subjected to alkaline solution (20% KOH) and a λ_max at 450 nm was detected for acetone extracts, although no typical fine structure of carotenoids was detected in the electomagnetic spectra. The HPLC profile of the extracted pigment showed that the compound has three different peaks with λ_max near 450 nm. The FTIR analysis shows some principal functional groups from a flexirubin-like molecule. The pigmented compound also presents antioxidant activity evaluated by the scavenging of the ABTS radical.     

Production,purification and partial characterization of a new adhesive factor (F42) produced by enterotoxigenic Escherichia coli isolated from pigs

Production of the F42 adhesive factor by porcine enterotoxigenic Escherichia coli (ETEC) grown on minimal solid medium was glucose-dependent. The addition of alanine and sodium acetate to this medium repressed the expression of this antigen whose production was also inhibited when the pH of the growing medium was lower than 7.4. The antigen was extracted from F42-positive ETEC grown in minimal liquid medium supplemented with 0.5% glucose. The cells were suspended in buffered 1 M NaCl and heated at 60°C. The supernatant was then treated with ammonium sulphate and the resulting precipitate treated with deoxycholate followed by chromatography of the deoxycholate-soluble material on Sepharose-4B. The molecular weight of F42 purified antigen was near 31,000 daltons and its pI 3.2, as determined by polyacrylamide gel electrophoresis and isoelectric focusing, respectively. Immunoelectrophoretic studies showed that the purified F42 antigen presented a slight anodic migration and was recognized only by its homologous antiserum.     

Aromatic butenolides produced by a soil ascomycete Auxarthron sp. KCB15F070 derived from a volcanic island

LC/MS-based chemical screening of fungal extract fraction library led to identification of three 2,3-aryl substituted furanone metabolites (1–3), including one known butenolide glycoside (1) whose stereochemistry remained unsolved and two new compounds gotjawaside and gotjawalide (2 and 3), from Auxarthron sp. KCB15F070, a fungus isolated from a soil sample of the volcanic island Jeju, Korea. Their planar structures were elucidated by 1D- and 2D-NMR spectroscopic and HRESIMS spectrometric techniques, and the absolute configurations of three compounds were solved using a combination of chemical derivatizations and computational analysis of vibrational circular dichroism (VCD) spectra.     

Aspergilolide,a steroid lactone produced by an endophytic fungus Aspergillus sp. MBL1612 isolated from Paeonia ostii

A new steroid lactone aspergilolide (1), and nine known compounds helvolic acid (2), verruculogen (3), tryprostatin B (4), 13-oxofumitremorgin B (5), fumitremorgin C (6), demethoxy fumitremorgin C (7), terezine D (8), aszonalenin (9), 12, 13-dihydroxy-fumitremorgin C (10) from cultures of the endophytic fungus Aspergillus sp. MBL1612. Their chemical structures were determined by a series of extensive spectroscopic methods. All of the compounds were isolated from this genus for the first time. The cytotoxicity against five human cancer cell lines of new compound were detected.     

Isolation and characterization of neurotoxins from the venom of the spiderAnemesia sp.

Three neurotoxin fractions have been isolated from the venom of the spider Anemesia sp. On interacting with a presynaptic membrane, two of them (An4 and Any) caused an enhancement of the secretion of the mediator and exhaustion of its reserves, while the third (An7) caused suppression of the amplitude of the synaptic potentials.Institute of Physiology and Biophysics, Academy of Sciences of the Republic of Uzbekistan, 700095, Tashkent, ul. Niyazova, 1. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 471–473, May–June, 1995. October 24, 1994.     

Isolation and characterization of thermophilic benzothiophene-degrading Mycobacterium sp.

A bacterial strain, SWU-4, capable of using benzothiophene (BT) as a sole carbon and energy source was isolated from a petroleum-contaminated site in Thailand and identified by 16S rRNA gene sequence analysis to be in the genus of Mycobacterium. The strain was Gram-positive, nonspore former, and grew at 50° C. Colonies of the strain on nutrient agar were rod-shaped, smooth with a convex surface, slightly mucoid, and yellow pigmented. The thermophilic Mycobacterium sp. strain SWU-4 rapidly degraded 2% (w/v) BT at 50°C. Interestingly, this strain was able to degrade a wide variety of organosulfur compounds including thiophene, bromo(α)thiophene, and 3-methylthiophene in liquid minimum medium at 50°C, which will be beneficial for industrial applications.     

Isolation of individual capsaicinoids from a mixture and their characterization by (13)C NMR spectrometry

Individual compounds were isolated from a laboratory mixture of capsaicinoids by a multi-stage approach. First, the capsaicinoids were fractionated into capsaicins and non-capsaicins by argentation solid phase extraction (SPE) on a silver-charged propyl sulfonate resin. Second, compounds in each fraction were isolated by semi-preparative liquid chromatography on a C₃₀ phase in aqueous methanol. Third, the individual components of the original mixture were concentrated by reversed phased (C₁₈) SPE. The structure of each purified compound was confirmed by ¹³C NMR spectrometry and spectral comparison to known standards, purchased or synthesized locally. The chemical shifts of 15 capsaicinoid standards were measured on a 600 MHz instrument, and their assignments to particular carbons were made by reference to Distortionless Enhancement by Polarization Transfer (DEPT) NMR experiments and NMR spectral prediction software.     

Padanamides A and B, highly modified linear tetrapeptides produced in culture by a Streptomyces sp. isolated from a marine sediment

Two highly modified linear tetrapeptides, padanamides A (1) and B (2), are produced by laboratory cultures of a Streptomyces sp. obtained from a marine sediment. Padanamide B is cytotoxic to Jurkat cells, and a chemical genomics analysis using Saccharomyces cerevisiae deletion mutants suggested that padanamide A inhibits cysteine and methionine biosynthesis or that these amino acids are involved in the yeast's response to the peptide.     

Isolation of polyhydroxyalkanoate-producing bacteria from a polluted soil and characterization of the isolated strain Bacillus cereus YB-4

We describe the characterization of polyhydroxyalkanoate (PHA)-producing bacteria isolated from an ammunition-polluted soil in Kitakyushu City, Japan. Over 270 strains were evaluated for PHA accumulation based on a colony staining method using Nile red. Of these, nine strains were selected based on the intensity of Nile red fluorescence and the cells were quantitatively analyzed for PHA by gas chromatography. PHA accumulation was observed in five strains, all of which are inferred to be close to the Bacillus cereus group according to 16S rDNA sequence analysis. Interestingly, these strains produced a PHA copolymer, poly(3-hydroxybutyrae-co-3-hydroxyvalerate) [P(3HB-co-3HV)], with a 3HV fraction up to 2 mol% with glucose as a carbon source. Further characterization was performed on one isolate, B. cereus YB-4. Gel permeation chromatography analysis revealed that the number of average molecular weights of PHA accumulated in B. cereus YB-4 drastically changed from 722,000 to 85,000 over a 72-h cultivation period. Furthermore, the PHA synthase genes were cloned and the deduced amino acid sequences were determined. This study provides new insights into PHA biosynthesis by members of the B. cereus group.     

Isolation of a Novel Polyketide from Neodidymelliopsis sp.

Fungi have become an invaluable source of bioactive natural products, with more than 5 million species of fungi spanning the globe. Fractionation of crude extract of Neodidymelliopsis sp., led to the isolation of a novel polyketide, (2Z)-cillifuranone (1) and five previously reported natural products, (2E)-cillifuranone (2), taiwapyrone (3), xylariolide D (4), pachybasin (5), and N-(5-hydroxypentyl)acetamide (6). It was discovered that (2Z)-cillifuranone (1) was particularly sensitive to ambient temperature and light resulting in isomerisation to (2E)-cillifuranone (2). Structure elucidation of all the natural products were conducted by NMR spectroscopic techniques. The antimicrobial activity of 2, 3, and 5 were evaluated against a variety of bacterial and fungal pathogens. A sodium [1-¹³C] acetate labelling study was conducted on Neodidymelliopsis sp. and confirmed that pachybasin is biosynthesised through the acetate polyketide pathway.     

Halomonas sp. OKOH--a marine bacterium isolated from the bottom sediment of Algoa Bay--produces a polysaccharide bioflocculant: partial characterization and biochemical analysis of its properties

A bioflocculant-producing bacterium isolated from seawater was identified based on 16S rRNA gene nucleotide sequence to have 99% similarity to that of Halomonas sp. Au160H and the nucleotide sequence was deposited as Halomonas sp. OKOH (Genbank accession number is HQ875722). Influences of carbon source, nitrogen source, salt ions and pH on flocculating activity were investigated. The bioflocculant was optimally produced when glucose (87% flocculating activity) and urea (88% flocculating activity) were used as sources of carbon and nitrogen, respectively. Also, initial pH of 7.0 and Ca2? supported optimal production of the bioflocculant with flocculating activities of 87% respectively. Chemical analyses revealed the bioflocculant to be a polysaccharide.     

Ascomycotin A,a new citromycetin analogue produced by Ascomycota sp. Ind19F07 isolated from deep sea sediment

A new citromycetin analogue, ascomycotin A (1), together with eight known compounds, wortmannilactone E (2), orcinol (3), orsellinic acid (4), isosclerone (5), (3R,4S)-( ? )-4-hydroxymellein (6), diorcinol (7), chaetocyclinone B (8) and 2,5-dimethoxy-3,6-di(p-methoxypheny1)-1,4-benzoquinone (9), was isolated from the fungal strain Ascomycota sp. Ind19F07, which was isolated from the deep sea sediment of the Indian Ocean. The structures of the compounds were established by spectroscopic data including 1D and 2D NMR and HR-ESI-MS. Compounds (1–9) were evaluated for antibacterial activity.