Cassava flour wastewater as a substrate for biosurfactant production

Five cassava flour wastewater (manipueira) preparations were tested as culture media for biosurfactant production by a wild-type Bacillus sp. isolate. No-solids (F), no-solids diluted (F/2), natural (I), natural diluted (I/2), and decanted (IPS) were the tested manipueira media. The microorganism was able to grow and to produce biosurfactant on all manipueira preparations. The media whose solids were removed (F and F/2) showed better results than preparations with the presence of solids (I, I/2, and IPS). No-solids medium (F) showed a surface tension of 26,59 mN/m and reciprocal of critical micelle concentration of over 100 and was selected as a potential substrate for biosurfactant production.     

Chloctanspirones A and B, novel chlorinated polyketides with an unprecedented skeleton, from marine sediment derived fungus Penicillium terrestre

Two novel chlorinated sorbicillinoids named chloctanspirones A (1) and B (2), possessing an unprecedented bicyclo[2.2.2]octane-2-spiro cyclohexane skeleton, together with their quasi-precursors terrestrols K (3) and L (4), two additional new chlorinated compounds, were isolated from a marine sediment derived fungus Penicillium terrestre. Their structures including absolute stereochemistries were elucidated by analysis of NMR, MS data, and TDDFT CD calculations. The cytotoxic effects of 1-4 were preliminarily evaluated in HL-60 and A-549 cells. Compound 1 was active against both HL-60 and A-549 cells with IC₅₀s 9.2 and 39.7 μM, respectively, while 2 showed weaker activity only against HL-60 cells (IC₅₀ 37.8 μM).     

Penicillilactone A,a novel antibacterial 7-membered lactone derivative from the sponge-associated fungus Penicillium sp. LS54

One novel 7-membered lactone derivative, penicillilactone A (1), together with two known compounds, rugulosin A (2) and rugulosin (3) were isolated from the sponge-derived fungus Penicillium sp. LS54. Their structures were elucidated on the basis of spectroscopic analysis and comparison with literature data. Remarkably, penicillilactone A (1) is the first natural product containing a 7-membered lactone ring fused with a furan core. Penicillilactone A (1) exhibited moderate antibacterial activity against aquatic pathogen Vibrio harveyi with an MIC value of 8 μg/mL.     

The influence of vegetable oils on biosurfactant production by Serratia marcescens

The production of biosurfactant, a surface-active compound, by two Serratia marcescens strains was tested on minimal culture medium supplemented with vegetable oils, considering that it is well known that these compounds stimulate biosurfactant production. The vegetable oils tested included soybean, olive, castor, sunflower, and coconut fat. The results showed a decrease in surface tension of the culture medium without oil from 64.54 to 29.57, with a critical micelle dilution (CMD⁻¹) and CMD⁻² of 41.77 and 68.92 mN/m, respectively. Sunflower oil gave the best results (29.75 mN/m) with a CMD⁻¹ and CMD⁻² of 36.69 and 51.41 mN/m, respectively. Sunflower oil contains about 60% of linoleic acid. The addition of linoleic acid decreased the surface tension from 53.70 to 28.39, with a CMD⁻¹ of 29.72 and CMD⁻² of 37.97, suggesting that this fatty acid stimulates the biosurfactant production by the LB006 strain. In addition, the crude precipitate surfactant reduced the surface tension of water from 72.00 to 28.70 mN/m. These results suggest that the sunflower oil’s linoleic acid was responsible for the increase in biosurfactant production by the LB006 strain.     

Biosurfactant production by Rhodococcus erythropolis grown on glycerol as sole carbon source

The production of biosurfactant by Rhodococcus erythropolis during the growth on glycerol was investigated. The process was carried out at 28°C in a 1.5-L bioreactor using glycerol as carbon source. The bioprocess was monitored through measurements of biosurfactant concentration and glycerol consumption. After 51 h of cultivation, 1.7 g/L of biosurfactant, surface, and interfacial tensions values (with n-hexadecane) of 43 and 15 mN/m, respectively, 67% of Emulsifying Index (E ₂₄), and 94% of oil removal were obtained. The use of glycerol rather than what happens with hydrophobic carbon source allowed the release of the biosurfactant, originally associated to the cell wall.     

Optimization of biosurfactant lipopeptide production from Bacillus subtilis S499 by Plackett-Burman design

Bacillus subtilis S499 is well-known for its ability to produce two families of surfactant lipopeptides: Iturin A and Surfactin S1. Fermentation optimization for this strain was performed to amplify the surfactant production. Ten active variables were analyzed by two successive Plackett-Burman designs, consisting respectively of 12 and 16 experiments to give an optimized medium. The amount of biosurfactant lipopeptides in the supernatant of a culture carried out in this optimized medium was about five times higher than that obtained in nonoptimized rich medium. The analysis of the surfactant molecules produced in such optimized conditions has revealed the presence of a third family of lipopeptides: the fengycins. The time-dependent production of these three families of molecules in bioreactors showed that surfactin S1 is produced during the exponential phase and iturin A and fengycins during the stationary phase.     

Bromine-containing alkaloids from the marine sponge Penares sp.

Two new unusual alkaloids were isolated from the sponge Penares sp., collected from Viet Nam waters (the South China Sea). The structures of these compounds were established by analysis of 1D, 2D NMR (¹H-¹H COSY, DEPT, HSQC, HMBC, H2BC, and NOE), and MS data. Compound 1 shows moderate cytotoxicity against the human tumor cells HL-60 and HeLa.     

Ircinamine B, bioactive alkaloid from marine sponge Dactylia sp.

Ircinamine B was isolated from the marine sponge Dactylia sp., which was collected at Cape Sada in Japan. Based on extensive spectral analysis, the structures of the isolated metabolites were established. This novel compound showed moderate activity against the murine leukemia cell line P388 (IC₅₀ 0.28 μg/mL).     

Marine bacterial inhibitors from the sponge-derived fungus Aspergillus sp.

Chromatographic separation of a crude extract obtained from the fungus Aspergillus sp., isolated from the Mediterranean sponge Tethya aurantium, yielded a new tryptophan derived alkaloid, 3-((1-hydroxy-3-(2-methylbut-3-en-2-yl)-2-oxoindolin-3-yl)methyl)-1-methyl-3,4-dihydrobenzo[e][1,4]diazepine-2,5-dione (1), and a new meroterpenoid, austalide R (2), together with three known compounds (3–5). The structures of the new compounds were unambiguously elucidated on the basis of extensive one and two-dimensional NMR (¹H, ¹³C, COSY, HMBC, and ROESY) and mass spectral analysis. Interestingly, the compounds exhibited antibacterial activity when tested against a panel of marine bacteria, with 1 selectively inhibiting Vibrio species and 2 showing a broad spectrum of activity. In contrast, no significant activity was observed against terrestrial bacterial strains and the murine cancer cell line L5178Y.     

Chaetominedione, a new tyrosine kinase inhibitor isolated from the algicolous marine fungus Chaetomium sp.

A marine fungal isolate, identified as Chaetomium sp., was cultivated and found to produce a novel benzonaphthyridinedione derivative, chaetominedione (1). In addition to the known fungal metabolites, 2-furancarboxylic acid (2) and 5-(hydroxymethyl)-2-furancarboxylic acid (3) were obtained. The structures of all the compounds were determined based on extensive spectroscopic measurements (1D and 2D NMR, MS, UV, and IR). The total extract and compound 1 had significant inhibitory activity toward p56^lck tyrosine kinase (18.7% and 93.6% enzyme inhibition at 200 μg/mL, respectively).     

Eremophilane sesquiterenes from the marine fungus Penicillium sp. BL27-2

Six eremophilane sesquiterpenes were obtained from a marine fungus Penicillium sp. BL27-2. Their structures were elucidated as 3-acetyl-9, 7 （11）-dien-7a-hydroxy-8-oxoeremophilane （1）, 3-acetyl-13-deoxyphomenone （2）, Sporogen-AO 1 （3）, 7-hydro- xypetasol （4）, 8a-hydroxy-13-deo -xyphomenone （5） and 6-dehydropetasol （6） based on detailed NMR analysis. 1 was a new compound and 2 was obtained as a new natural compound. These compounds were assayed for their cytotoxic activity on P388, A549, HL60, BEL7402 and K562 cell lines by the MTT method. The assay results suggested the epoxide rings in eremophilane molecules were essential for their activity, and acetylation could enhance their activity.     

Aigialomycins and related polyketide metabolites from the mangrove fungus Aigialus parvus BCC 5311

Reinvestigation of the secondary metabolites from the marine mangrove fungus Aigialus parvus BCC 5311 led to the isolation of six new nonaketide metabolites, aigialomycins F (4) and G (5a/5b), 7′,8′-dihydroaigialospirol (7), 4′-deoxy-7′,8′-dihydroaigialospirol (8), and rearranged macrolides 9 and 10, along with six previously described compounds, hypothemycin (1), aigialomycins A (2) and B (3), aigialospirol (6), 4-O-demethylhypothemycin (11), and aigialone (12). The structures of the new compounds were elucidated by analyses of the NMR spectroscopic and mass spectrometry data in combination with chemical means.     

Siderophore production by a marine Pseudomonas aeruginosa and its antagonistic action against phytopathogenic fungi

A marine isolate of fluorescent Pseudomonas sp. having the ability to produce the pyoverdine type of siderophores under low iron stress (up to 10 μM iron in the succinate medium) was identified as Pseudomonas aeruginosa by using BIOLOG Breathprint and siderotyping. Pyoverdine production was optimum at 0.2% (w/v) succinate, pH 6.0, in an iron-deficient medium. Studies carried out in vitro revealed that purified siderophores and Pseudomonas culture have good antifungal activity against the plant deleterious fungi, namely, Aspergillus niger, Aspergillus flavus, Aspergillus oryzae, Fusarium oxysporum, and Sclerotium rolfsii. Siderophore-based maximum inhibition was observed against A. niger. These in vitro antagonistic actions of marine Pseudomonas against phytopathogens suggest the potential of the organism to serve as a biocontrol agent.     

Fatty-acid composition of certain species of marine mycelial fungi

The fatty-acid composition of seven strains of marine mycelial fungi was studied. GC and GC—MS showed that marine fungi of the genus Penicillium synthesized fatty-acid mixtures of saturated and unsaturated acids of similar compositions with different percent contents. Fatty-acid profiles of fungi associated with holothuria Chiridota ochotensis were characterized for the first time. Producers of branched 15:0 and dichloro- and cyclopropane-containing acids were observed. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 18–20, January-February, 2009.     

Colensolide A: a new nitrogenous bromophenol from the New Zealand marine red alga Osmundaria colensoi

A new nitrogenous bromophenol, colensolide A, is isolated from the New Zealand red alga Osmundaria colensoi together with the known bromophenol lanosol and four of its derivatives. In this study, a novel technique is employed to identify potentially new compounds in semi-purified mixtures containing a plethora of structurally similar, known metabolites, using NMR spectroscopy. The structure and relative configuration of colensolide A is determined using standard spectroscopic techniques. Several of the known bromophenols exhibit antibacterial activity and one shows moderate cytotoxicity.     

Adsorption on stainless steel surfaces of biosurfactants produced by gram-negative and gram-positive bacteria: Consequence on the bioadhesive behavior of Listeria monocytogenes

The ability of adsorbed biosurfactants (Pf and Lb) obtained from gram-negative bacterium (Pseudomonas fluorescens) or gram-positive bacterium (Lactobacillus helveticus) to inhibit adhesion of four listerial strains to stainless steel was investigated. These metallic surfaces were characterized using the following complementary analytical techniques: contact-angle measurements (CAM), atomic force microscopy (AFM), polarization modulation-infrared reflection-adsorption spectroscopy (PM-IRRAS) and X-ray photoelectron spectroscopy (XPS). Contact-angles with polar liquids (water and formamide) indicated that the stainless steel surface covered with adsorbed biosurfactant was more hydrophilic and electron-donating than bare stainless steel. The surface characterization by XPS and PM-IRRAS revealed that conditioning the stainless steel changes the substrate in two ways, by modifying the surface alloy composition and by leaving an thin adsorbed organic layer. AFM observations enabled to say that the layer covered entirely the surface and was probably thicker (with patches) in the case of Pf-conditioned surfaces compared to the Lb-conditioned ones, which seemed to be less homogeneous. Though the added layer was thin, significant chemical changes were observed that can account for drastic modifications in the surface adhesive properties. As a matter of fact, adhesion tests showed that both used biosurfactants were effective by decreasing strongly the level of contamination of stainless steel surfaces by the four strains of Listeria monocytogenes. The more important decrease concerned the CIP104794 and CIP103573 strains (>99.7%) on surface conditioned by L. helveticus biosurfactant. A less reduced phenomenon (75.2%) for the CIP103574 strain on stainless steel with absorbed biosurfactant from P. fluorescens was observed. Whatever the strain of L. monocytogenes and the biosurfactant used, this antiadhesive biologic coating reduced both total adhering flora and viable and cultivable adherent bacteria on stainless steel surfaces. This study confirms that biosurfactants constitute an effective strategy to prevent microbial colonization of metallic surfaces by pathogenic bacteria like the food-borne pathogen L. monocytogenes.     

Exiguolide, a new macrolide from the marine sponge Geodia exigua

A new 20-membered macrolide designated exiguolide has been isolated from the marine sponge Geodia exigua, and its structure determined by interpretation of spectroscopic data. Exiguolide specifically inhibited fertilization of sea urchin (Hemicentrotus pulcherrimus) gametes but not embryogenesis of the fertilized egg.     

An efficient biosurfactant-producing bacterium Pseudomonas aeruginosa MR01, isolated from oil excavation areas in south of Iran

A bacterial strain was isolated and cultured from the oil excavation areas in tropical zone in southern Iran. It was affiliated with Pseudomonas. The biochemical characteristics and partial sequenced 16S rRNA gene of isolate, MR01, was identical to those of cultured representatives of the species Pseudomonas aeruginosa. This bacterium was able to produce a type of biosurfactant with excessive foam-forming properties. Compositional analysis revealed that the extracted biosurfactant was composed of high percentages lipid (65%, w/w) and carbohydrate (30%, w/w) in addition to a minor fraction of protein (4%, w/w). The best production of 2.1 g/l was obtained when the cells were grown on minimal salt medium containing 1.2% (w/v) glucose and 0.1% (w/v) ammonium sulfate supplemented with 0.1% (w/v) isoleucine at 37 °C and 180 rpm after 2 days. The optimum biosurfactant production pH value was found to be 8.0. The MR01 could reduce surface tension to 28 mN/m and emulsified hexadecane up to E24  70. The results obtained from time course study indicated that the surface tension reduction and emulsification potential was increased in the same way to cell growth. However, maximum biosurfactant production occurred and established in the stationary growth phase (after 84 h). Fourier Transform Infrared spectrum of extracted biosurfactant indicates the presence of carboxyl, amine, hydroxyl and methoxyl functional groups. Thermogram of biosurfactant demonstrated three sharp endothermic peaks placing between 200 and 280 °C. The core holder flooding experiments demonstrated that the oil recovery efficiencies varied from 23.7% to 27.1% of residual oil.     

A unique feature of hydrogen recovery in endogenous starch-to-alcohol fermentation of the marine microalga, Chlamydomonas perigranulata

A unicellular marine green alga, Chlamydomonas perigranulata, was demonstrated to synthesize starch through photosynthesis, store it in a cell, and ferment it under anaerobic conditions in the dark to produce ethanol, 2,3-butanediol (butanediol), acetic acid, and carbon dioxide (CO₂). Previous fermentation data of an algal biomass cultivated outdoors in a 50-L tubular photo-bioreactor showed good carbon (C) recovery in the fermentation balance, with a higher ratio to alcohols and, therefore, lower ratio to CO₂ in the C distribution of products than what would be expected from the embden-Myerhof-Parnas pathway. These findings led to a proposed concept for a CO₂-ethanol conversion system (CDECS). The above data were evaluated in terms of hydrogen (H) recovery with the following results: C recovery at 105% was well balanced, although H recovery was as high as 139%, meaning an additional gain of H through fermentation. This finding was reproduced wholly in a set of experiments carried out in the same month of the following year, October, whereas another set of experiments was carried out in the following June provided ordinary fermentation results in terms of C and H recoveries with poor growth. Further analyses of these data revealed that butanediol is equal to ethanol as a product from a putative conversion system from CO₂ to the detected fermentation products, leading to the revision of the CDECS concept to a CO₂-alcohol conversion system (CDACS). The relevance of the CDACS will be discussed in relation to the cultivation conditions employed by chance.