Composição química e atividades biológicas de extratos e frações de Guadua chacoensis (Rojas) Londoño & P.M. Peterson / Chemical composition and biological activities of extracts and fractions of Guadua chacoensis (Rojas) Londoño & P.M. Peterson

O Brasil é o país que possui a maior diversidade de bambus em todo o continente americano, com mais de 200 espécies catalogadas. Devido à alta resistência e durabilidade, essas espécies são muito utilizadas na construção civil e confecção de móveis e utensílios. No entanto, faltam estudos que investiguem a composição química e as atividades biológicas. Neste projeto foram avaliados extratos etanólicos de folhas e colmos de Guadua chacoensis (Rojas) Londoño & P.M. Peterson e frações em hexano, clorofórmio, acetato de etila e n-butanol. Também se obteve o óleo volátil, mas com um rendimento extremamente baixo (0,00079%). As frações dos extratos apresentaram teores de compostos fenólicos variando entre 1,92 e 15,80 µg EAG/mg. Esses compostos mostraram-se mais abundantes nas amostras de colmos. Em relação ao teor de flavonoides, as folhas apresentaram maior quantidade, variando entre 0,39 e 1,18 µg EQ/mg contra 0,17 a 0,34 µg EQ/mg nos colmos. Investigou-se a atividade antimicrobiana dos extratos, frações e óleo volátil frente cinco microrganismos: Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans e Aspergillus brasiliensis. As amostras demonstraram potencial inibitório moderado a bom contra S. aureus e C. albicans, porém fraca para as demais espécies. Testou-se a capacidade antioxidante frente o radical DPPH e os resultados indicaram atividade antioxidante significativa, especialmente as frações acetato e butanol de colmos. As folhas apresentaram EC50 variando entre 67,5 e 124,0 µg/mL e os colmos entre 40,2 e 124 µg/mL. A inibição da enzima tirosinase, que está associada à produção de melanina, também se mostrou boa a uma concentração de 1 mg/mL, com o extrato bruto de colmos apresentando 43% de inibição, seguido pelas frações acetato (36%) e n-butanol (38%) de folhas. As análises por CG-MS detectaram pelo menos 44 compostos diferentes no óleo volátil, com vários terpenos e sesquiterpenos, e com ß-ionona sendo o componente majoritário (8,75%). As amostras de colmos e folhas apontaram grande diversidade de compostos, cerca de 20 para cada fração, onde os ácidos graxos como ácido palmítico e linoleico e seus ésteres derivados foram os mais abundantes. A análise dos perfis cromatográficos por CCD e CLAE revelaram a presença de ácido p-cumárico nos colmos de G. chacoensis. Esse composto tem relevante atividade antioxidante e de inibição da tirosinase. Também foi possível identificar a quercetagetina-7-O-glicosídeo, uma flavona glicosilada, com propriedades anti-inflamatorias e antidiabéticas. Desta forma, constatou-se que G. chacoensis apresenta grande diversidade de metabólitos secundários com atividades biológicas relevantes, como atividade antioxidante e clareadora, abrindo caminho para investigações mais profundas de suas aplicações, especialmente no segmento de cosméticos e produtos naturais

Brazil is the country with the greatest diversity of bamboo in the entire American continent, with more than 200 species catalogued. Due to their high resistance and durability, they are widely used in home construction and manufacture of furniture and utensils. However, studies investigating chemical composition and biological activities are absent. In this project, ethanol extracts from leaves and stems of Guadua chacoensis (Rojas) Londoño & P.M. Peterson and fractions in hexane, chloroform, ethyl acetate and n-butanol were evaluated. Volatile oil was also obtained, but with an extremely low yield (0.00079%). The fractions of the extracts presented contents of phenolic compounds varying between 1.92 and 15.80 µg GAE/mg. These compounds were more abundant in culm samples. In relation to the flavonoid content, leaves showed a greater amount, varying between 0.39 and 1.18 µg QE/mg against 0.17 to 0.34 µg QE/mg in culms. The antimicrobial activity of extracts, fractions and volatile oil were investigated against five microorganisms: Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans and Aspergillus brasiliensis. The samples showed moderate to good inhibitory potential against S. aureus and C. albicans, but weak for the other species. The antioxidant capacity was tested against the DPPH radical and the results indicated significant antioxidant activity, especially acetate and butanol culm fractions. The leaves presented EC50 varying between 67.5 and 124.0 µg/mL and culms between 40.2 and 124 µg/mL. The inhibition of the enzyme tyrosinase, which is associated with the production of melanin, was also shown to be good at a concentration of 1 mg/mL, with the raw culm extract showing 43% inhibition, followed by acetate (36%) and n-butanol (38%) fractions of leaves. CG-MS analysis detected at least 44 different compounds in volatile oil, with several terpenes and sesquiterpenes, and with ß-ionone being the major component (8.75%). Culm and leaf samples showed great diversity of compounds, about 20 for each fraction, where fatty acids such as palmitic and linoleic acid and their derivative esters were the most abundant. The analysis of the chromatographic profiles by TLC and HPLC revealed the presence of p-coumaric acid in culms of G. chacoensis. This compound has relevant antioxidant and tyrosinase inhibiting activity. It was also possible to identify quercetagetine-7-O-glucoside, a glycosylated flavone, with anti-inflammatory and anti-diabetic properties. Thus, it was found that G. chacoensis presents a great diversity of secondary metabolites with relevant biological activities, such as antioxidant and whitening activity, opening ways for deeper investigations of its applications, especially in the segment of cosmetics and natural products

Statistical optimization of kojic acid production by a UV-induced mutant strain of Aspergillus terreus

ABSTRACT The ability of four Aspergillus strains for biosynthesis of kojic acid was evaluated among which Aspergillus terreus represented the highest level (2.21 g/L) of kojic acid production. Improvement kojic acid production ability of A. terreus by random mutagenesis using different exposure time to ultraviolet light (5-40 min) was then performed to obtain a suitable mutant of kojic acid production (designated as C5-10, 7.63 g/L). Thereafter, design of experiment protocol was employed to find medium components (glucose, yeast extract, KH2PO4 (NH4)2SO4, and pH) influences on kojic acid production by the C5-10 mutant. A 25-1 fractional factorial design augmented to central composite design showed that glucose, yeast extract, and KH2PO4 were the most considerable factors within the tested levels (p < 0.05). The optimum medium composition for the kojic acid production by the C5-10 mutant was found to be glucose, 98.4 g/L; yeast extract, 1.0 g/L; and KH2PO4, 10.3 mM which was theoretically able to produce 120.2 g/L of kojic acid based on the obtained response surface model for medium optimization. Using these medium compositions an experimental maximum Kojic acid production (109.0 ± 10 g/L) was acquired which verified the efficiency of the applied method.

The occurrence of aflatoxigenic Aspergillus spp. in dairy cattle feed in Southern Brazil

ABSTRACT The presence of mycotoxins or related fungi in animal feed is a major problem for animal and human health. Silage and concentrated feed samples were collected from 21 dairy farms in the Western part of Paraná state in Southern Brazil. Water activity and pH of all samples were measured, and each sample was analyzed to check for the presence of aflatoxigenic Aspergillus. Water activity was observed to be lower in the concentrated feed samples. The pH was lower in the silage samples, indicating fermentation processes. Two silage samples and four concentrated feed samples were contaminated with Aspergillus spp. Seven isolates of Aspergillus spp. were obtained and their potential to produce aflatoxins was evaluated. Four of the isolates, two from the silage samples and two from the concentrated feed samples, produced the aflatoxins B1, B2, G1, and G2 in culture media. These isolates were identified as Aspergillus parasiticus and Aspergillus nomius. The presence of aflatoxigenic isolates of Aspergillus spp. in silage and concentrated feed samples is a matter of concern, because of the risk of aflatoxin production and contamination of the animal feed.

Fusarium and Aspergillus mycotoxins contaminating wheat silage for dairy cattle feeding in Uruguay

Abstract Wheat is one of the most important cultivated cereals in Uruguay for human consumption; however, when harvest yields are low, wheat is usually used in ensiling for animal feeding. Ensiling is a forage preservation method that allows for storage during extended periods of time while maintaining nutritional values comparable to fresh pastures. Silage is vulnerable to contamination by spoilage molds and mycotoxins because ensilage materials are excellent substrates for fungal growth. The aim of the study was to identify the mycobiota composition and occurrence of aflatoxins and DON from wheat silage. A total of 220 samples of wheat were collected from four farms in the southwest region of Uruguay were silage practices are developed. The main fungi isolated were Fusarium (43%) and Aspergillus (36%), with Fusarium graminearum sensu lato and Aspergillus section Flavi being the most prevalent species. Aflatoxin concentrations in silo bags ranged from 6.1 to 23.3 µg/kg, whereas DON levels ranged between 3000 µg/kg and 12,400 µg/kg. When evaluating aflatoxigenic capacity, 27.5% of Aspergillus section Flavi strains produced AFB1, 5% AFB2, 10% AFG1 and 17.5% AFG2. All isolates of F. graminearum sensu lato produced DON and 15-AcDON. The results from this study contribute to the knowledge of mycobiota and mycotoxins present in wheat silage.

Enhanced alkaline cellulases production by the thermohalophilic Aspergillus terreus AUMC 10138 mutated by physical and chemical mutagens using corn stover as substrate

Abstract A thermohalophilic fungus, Aspergillus terreus AUMC 10138, isolated from the Wadi El-Natrun soda lakes in northern Egypt was exposed successively to gamma and UV-radiation (physical mutagens) and ethyl methan-sulfonate (EMS; chemical mutagen) to enhance alkaline cellulase production under solid state fermentation (SSF) conditions. The effects of different carbon sources, initial moisture, incubation temperature, initial pH, incubation period, inoculum levels and different concentrations of NaCl on production of alkaline filter paper activity (FPase), carboxymethyl cellulase (CMCase) and β-glucosidase by the wild-type and mutant strains of A. terreus were evaluated under SSF. The optimum conditions for maximum production of FPase, CMCase and β-glucosidase were found to be the corn stover: moisture ratio of 1:3(w/v), temperature 45 °C, pH range, 9.0–11.0, and fermentation for 4, 4 and 7 day, respectively. Inoculum levels of 30% for β-glucosidase and 40% for FPase, CMCase gave the higher cellulase production by the wild-type and mutant strains, respectively. Higher production of all three enzymes was obtained at a 5% NaCl. Under the optimized conditions, the mutant strain A. terreus M-17 produced FPase (729 U/g), CMCase (1,783 U/g), and β-glucosidase (342 U/g), which is, 1.85, 1.97 and 2.31-fold higher than the wild-type strain. Our results confirmed that mutant strain M-17 could be a promising alkaline cellulase enzyme producer employing lignocellulosics especially corn stover.

Morphological changes and growth of filamentous fungi in the presence of high concentrations of PAHs

In this study, we evaluated the effect of low and high molecular weight polycyclic aromatic hydrocarbons (PAHs), i.e., Phenanthrene, Pyrene and Benzo[a]pyrene, on the radial growth and morphology of the PAH-degrading fungal strains Aspergillus nomius H7 and Trichoderma asperellum H15. The presence of PAHs in solid medium produced significant detrimental effects on the radial growth of A. nomius H7 at 4,000 and 6,000 mg L⁻¹ and changes in mycelium pigmentation, abundance and sporulation ability at 1,000–6,000 mg L⁻¹. In contrast, the radial growth of T. asperellum H15 was not affected at any of the doses tested, although sporulation was observed only up to 4,000 mg L⁻¹ and as with the H7 strain, some visible changes in sporulation patterns and mycelium pigmentation were observed. Our results suggest that fungal strains exposed to high doses of PAHs significantly vary in their growth rates and sporulation characteristics in response to the physiological and defense mechanisms that affect both pigment production and conidiation processes. This finding is relevant for obtaining a better understanding of fungal adaptation in PAH-polluted environments and for developing and implementing adequate strategies for the remediation of contaminated soils.

Production of plant cell wall degrading enzymes by monoculture and co-culture of Aspergillus niger and Aspergillus terreus under SSF of banana peels

Filamentous fungi are considered to be the most important group of microorganisms for the production of plant cell wall degrading enzymes (CWDE), in solid state fermentations. In this study, two fungal strains Aspergillus niger MS23 and Aspergillus terreus MS105 were screened for plant CWDE such as amylase, pectinase, xylanase and cellulases (β-glucosidase, endoglucanase and filterpaperase) using a novel substrate, Banana Peels (BP) for SSF process. This is the first study, to the best of our knowledge, to use BP as SSF substrate for plant CWDE production by co-culture of fungal strains. The titers of pectinase were significantly improved in co-culture compared to mono-culture. Furthermore, the enzyme preparations obtained from monoculture and co-culture were used to study the hydrolysis of BP along with some crude and purified substrates. It was observed that the enzymatic hydrolysis of different crude and purified substrates accomplished after 26 h of incubation, where pectin was maximally hydrolyzed by the enzyme preparations of mono and co-culture. Along with purified substrates, crude materials were also proved to be efficiently degraded by the cocktail of the CWDE. These results demonstrated that banana peels may be a potential substrate in solid-state fermentation for the production of plant cell wall degrading enzymes to be used for improving various biotechnological and industrial processes.

Production of bioethanol using agricultural waste: banana pseudo stem

India is amongst the largest banana (Musa acuminata) producing countries and thus banana pseudo stem is commonly available agricultural waste to be used as lignocellulosic substrate. Present study focuses on exploitation of banana pseudo stem as a source for bioethanol production from the sugars released due to different chemical and biological pretreatments. Two fungal strains Aspergillus ellipticus and Aspergillus fumigatus reported to be producing cellulolytic enzymes on sugarcane bagasse were used under co-culture fermentation on banana pseudo stem to degrade holocellulose and facilitate maximum release of reducing sugars. The hydrolysate obtained after alkali and microbial treatments was fermented by Saccharomyces cerevisiae NCIM 3570 to produce ethanol. Fermentation of cellulosic hydrolysate (4.1 g%) gave maximum ethanol (17.1 g/L) with yield (84%) and productivity (0.024 g%/h) after 72 h. Some critical aspects of fungal pretreatment for saccharification of cellulosic substrate using A. ellipticus and A. fumigatus for ethanol production by S. cerevisiae NCIM 3570 have been explored in this study. It was observed that pretreated banana pseudo stem can be economically utilized as a cheaper substrate for ethanol production.

Modulation of antimicrobial metabolites production by the fungus Aspergillus parasiticus

Biosynthesis of active secondary metabolites by fungi occurs as a specific response to the different growing environments. Changes in this environment alter the chemical and biological profiles leading to metabolites diversification and consequently to novel pharmacological applications. In this work, it was studied the influence of three parameters (fermentation length, medium composition and aeration) in the biosyntheses of antimicrobial metabolites by the fungus Aspergillus parasiticus in 10 distinct fermentation periods. Metabolism modulation in two culturing media, CYA and YES was evaluated by a 2² full factorial planning (ANOVA) and on a 2³ factorial planning, role of aeration, medium composition and carbohydrate concentration were also evaluated. In overall, 120 different extracts were prepared, their HPLC profiles were obtained and the antimicrobial activity against A. flavus, C. albicans, E. coli and S. aureus of all extracts was evaluated by microdilution bioassay. Yield of kojic acid, a fine chemical produced by the fungus A. parasiticus was determined in all extracts. Statistical analyses pointed thirteen conditions able to modulate the production of bioactive metabolites by A. parasiticus. Effect of carbon source in metabolites diversification was significant as shown by the changes in the HPLC profiles of the extracts. Most of the extracts presented inhibition rates higher than that of kojic acid as for the extract obtained after 6 days of fermentation in YES medium under stirring. Kojic acid was not the only metabolite responsible for the activity since some highly active extracts showed to possess low amounts of this compound, as determined by HPLC.

Optimization of lipid enriched biomass production from oleaginous fungus using response surface methodology.

Oleaginous microorganisms have emerged as potential sources of oils for biodiesel production. To replenish as an alternative to the vegetable oils, higher lipid accumulating strain coupled with process optimization is indispensable. In the present study, response surface methodology (RSM) based central composite design (CCD) was used for optimization of lipid content from oleaginous fungus Aspergillus sp. Maximum lipid yield of 73.07% (w/w) was achieved at 3% (v/v) inoculum volume, pH 5, glucose 1% (w/v), urea 0.5 % (w/v) and incubation time of 5 (days). Biomass (2.08 g/L) having a lipid content of 73.07 % (w/w) with major constituents of hexadecanoic acid methyl ester and 9-Octadecenoic acid methyl ester were obtained. The lipid composition signifies that from the oleaginous microbe are highly encouraging and desirable to be considered as diesel substitute.

Ochratoxigenic fungi associated with green coffee beans (Coffea arabica L.) in conventional and organic cultivation in Brazil

The genera Aspergillus comprises species that produce mycotoxins such as aflatoxins, ochratoxins and patulin. These are cosmopolitan species, natural contaminants of agricultural products. In coffee grains, the most important Aspergillus species in terms of the risk of presenting mycotoxins belong to the genera Aspergillus Section Circumdati and Section Nigri. The purpose of this study was to assess the occurrence of isolated ochratoxigenic fungi of coffee grains from organic and conventional cultivation from the South of Minas Gerais, Brazil, as well as to evaluate which farming system presents higher contamination risk by ochratoxin A (OTA) produced by fungi. Thirty samples of coffee grains (Coffea arabica L.) were analysed, being 20 of them of conventional coffee grains and 10 of them organic. The microbiological analysis was done with the Direct Plating Technique in a Dichloran Rose Bengal Chloramphenicol Agar (DRBC) media. The identification was done based on the macro and micro morphological characteristics and on the toxigenic potential with the Plug Agar technique. From the 30 samples analysed, 480 filamentous fungi of the genera Aspergillus of the Circumdati and Nigri Sections were isolated. The ochratoxigenic species identified were: Aspergillus auricoumus, A. ochraceus, A. ostianus, A. niger and A. niger Aggregate. The most frequent species which produces ochratoxin A among the isolated ones was A. ochraceus, corresponding to 89.55%. There was no significant difference regarding the presence of ochratoxigenic A. ochreceus between the conventional and organic cultivation systems, which suggests that the contamination risk is similar for both cultivation systems.

The potential effects of Zataria multiflora Boiss essential oil on growth, aflatoxin production and transcription of aflatoxin biosynthesis pathway genes of toxigenic Aspergillus parasiticus

This study aims at evaluating the effects of Zataria multiflora (Z. multiflora) essential oil (EO) on growth, aflatoxin production and transcription of aflatoxin biosynthesis pathway genes. Total RNAs of Aspergillus parasiticus (A.parasiticus) ATCC56775 grown in yeast extract sucrose (YES) broth medium treated with Z. multiflora EO were subjected to reverse transcription-polymerase chain reaction (RT-PCR). Specific primers of nor-1, ver-1, omt-A and aflR genes were used. In parallel mycelial dry weight of samples were measured and all the media were assayed by high-pressure liquid chromatography (HPLC) for aflatoxinB1 (AFB1), aflatoxinB2 (AFB2), aflatoxinG1 (AFG1), aflatoxinG2 (AFG2) and aflatoxin total (AFTotal) production. The results showed that mycelial dry weight and aflatoxin production reduce in the presence of Z. multiflora EO (100 ppm) on day 5 of growth. It was found that the expression of nor-1, ver-1, omt-A and aflR genes was correlated with the ability of fungus to produce aflatoxins on day 5 in YES medium. RT-PCR showed that in the presence of Z.multiflora EO (100 ppm) nor-1, ver-1 and omtA genes expression was reduced. It seems that toxin production inhibitory effects of Z. multiflora EO on day 5 may be at the transcription level and this herb may cause reduction in aflatoxin biosynthesis pathway genes activity.

Modification of c and n sources for enhanced production of cyclosporin 'a' by Aspergillus Terreus

Most of the studies regarding cyclosporin 'A' production through fungi concentrate around Tolypocladium inflatum. This is mainly due to lower reported production of this drug in other fungi. The present study was therefore conducted to explore indigenous isolates of Aspergillus terreus for synthesis of this drug and defining a production medium for obtaining high yield of cyclosporin 'A'. For this purpose carbon and nitrogen sources were optimized for the selected best strain of A. terreus. Overall results depicted that the best cyclosporin 'A' yield from selected Aspergillus terreus (FCBP58) could be obtained by using production medium containing glucose 10 percent as carbon source and peptone 0.5 percent as nitrogen source. This modification in production medium enhanced drug synthesis by selected fungi significantly. The production capabilities when compared with biomass of fungi there was found no relationship between the two confirming that the medium modification increased overall drug synthesis powers of the fungi.

Culture conditions for the production of a-galactosidase by Aspergillus parasiticus MTCC-2796: a novel source / Condiciones del cultivo para la producción de a-galactosidasa por Aspergillus parasiticus MTCC-2796: una nueva fuente

Aspergillus parasiticus microbial type culture collection (MTCC)-2796, a new source of a-galactosidase is an efficient producer of enzyme in basic medium under submerged fermentation conditions. Maximum a-galactosidase production (156.25 Uml-1) was obtained when the basic medium is supplemented with galactose (0.5 percent w/v) and raffinose (0.5 percent w/v) as carbon source and yeast extract as nitrogen source. Enzyme production was also enhanced considerably in the presence of wheat bran (1.0 percent w/v). Enzyme secretion was strongly inhibited by the presence of Hg2+, Cu2+, and Co2+ in the medium and to some extent by Zn2+ and Ni2+, while marginal increase in the enzyme production was observed when Mg2+ and Mn2+ were added in the medium. Among amino acids checked (aparagine, cysteine, glutamine, leucine and proline), glutamine (1 mM) was found to be an enhancer for the enzyme production. The temperature and pH range for the production of enzyme were 25ºC to 35ºC and 6.5 to 7.5, respectively with maximum activity (50 Uml-1) at 30ºC and pH 6.5 under static fermentation condition.

Kinetic study on inducibility of polygalacturonases from Aspergillus flavipes FP-500

The aim of this work was to describe growth dynamics, substrate depletion and polygalacturonases production by Aspergillus flavipes FP-500 in batch cultures by means of unstructured models. The microorganism was cultivated on several mono- di- and poly- saccharides, and then the culture development modeled with Monod and Leudeking-Piret equations. The kinetic parameters related to the models (µmax, ãx/s, alpha and beta) were obtained by minimizing the quadratic residuals function with a simplex algorithm. An accurate description of experimental data was attained with the proposed models. Besides, modeling provided significant kinetic information on microbial degradation of complex substrates, such as the correlation between specific growth rate µmax and production yield á, suggesting that A. flavipes FP-500 polygalacturonases are actually constitutive, but also that there is a certain degree of induciblility in these enzymatic activities.

Process of rock phosphate solubilization by Aspergillus sp PS 104 in soil amended medium.

Aspergillus sp PS 104, a soil isolate had excellent potential to solubilize rock phosphate in vitro. The process was influenced by the presence of various concentrations of local loess (red soil). The simultaneous occurrence, in our experiment, of high levels of solubilized phosphate and synthesized citric acid, together with the lowest reached pH values, confirmed the role of citric acid in the phosphate solubilization mechanism. When the soil was present, phosphate release was better correlated than citrate synthesis with H+ concentration. Changes in soluble phosphate concentration did not follow a sigmoid pattern. The ability of organism to release phosphatase was also studied. An interesting relationship was observed between the two processes of phosphate mobilization: citric acid synthesis and phosphatase production.

Response of fungal community in the unpolluted and polluted (textile and distillery wastes) habitats.

37 fungal species were recorded, maximum found in textile wastewater polluted habitats (35) followed by unpolluted (15) and distillery polluted (6) habitats. Fungal diversity in sediment samples of textile wastewater polluted habitats (25) was a little lower than wastewater samples (32), whereas it varied little both in the samples of unpolluted habitats (Sambhar wetlands: 5-6; Garden tanks: 9-10) and distillery waste (3-5). Seasonal variation in species diversity was more pronounced in the textile wastewater polluted habitats. Their minimum number was often found during the rainy season while maximum in the winter season, in the polluted habitats but during summer in the unpolluted habitats. Aspergillus was the most diverse genus represented by 7 species, followed by Cladosporium and Fusarium (3 species each) while Drechslera, Rhizopus and Trichoderma had 2 species each. The remaining genera (18) were monotypic. Colony Forming Units (CFUs) were also maximum in the textile wastewater polluted habitats (5.6-1898.9 x 10(3)/L), followed by unpolluted (6.7-560.0 x 10(3)/L) and distillery waste polluted habitats (3.1-53.3 x 10(3)/L), being usually higher in the sediment samples. Their number also varied seasonally, being maximum during winter season in the water samples, whereas in summer in the sediment samples. Aspergillus fumigatus, A. niger, Cladosporium cladosporioides, C. sphaerospermum and Penicillium chrysogenum usually contributed maximum to the CFU values in the polluted as well as in unpolluted habitats.

Antioxidant and anti-inflammatory activity of extract obtained from Aspergillus candidus MTCC 2202 broth filtrate.

Antioxidant potential of Aspergillus candidus MTCC 2202 broth filtrate extract was studied using different antioxidant models, whereas anti-inflammatory potential was studied using carrageenan-induced rat paw oedema model. The ethyl acetate extract at 1000 microg/ml showed maximum scavenging activity of the stable radical 1,1-diphenyl,2-picryl hydrazyl upto 96.65% (IC50=430.36 microg/ml) and scavenging of the radical cation, 2,2-azinobis-(3-ethylbenzothiazoline-6-sulphonate) upto 92.25% (IC50=606.29 microg/ml) at the same concentration. The extract had good reducing power, however showed moderate inhibition for conjugated dienes and thiobarbituric acid reactive acid substances (59.56 and 51.45%). The total phenolic content of various extracts of A. candidus broth filtrate was measured and a correlation between radical scavenging activities of extracts with total phenolic content was observed. The ethyl acetate extract (125 mg/kg ip) showed significant anti-inflammatory activity in carrageenan-induced rat paw oedema model. The exhibited antioxidant activity of ethyl acetate extract of A. candidus broth filtrate was comparable with BHA and ascorbic acid, while anti-inflammatory activity was comparable with standard diclofenac sodium.

Chemical properties and NMR spectroscopic identification of certain fungal siderophores.

Siderophores of six fungi viz. Aspergillus sp. ABp4, Aureobacidium pullulans, Penicillium oxalicum, P. chrysosporium, Mycotypha africana and Syncephalastrum racemosum were examined for their (1) electrophoretic mobilities to determine the acidic, basic or neutral charge; (2) Fe (III) binding nature viz., mono-, di-, or trihydroxamate; (3) amino acid composition; and (4) NMR (nuclear magnetic resonance) spectroscopy to determine their structure. Electrophoretic mobilities of siderophores of 3 fungi (P. oxalicum, P. chrysosporium, and M, africana) exhibited net basic charge, siderophores of 2 fungi (Aspergillus sp. ABp4 and S. racemosum) were acidic and 1 fungus (A. pullullans) was neutral. Electrophoresis of ferrated siderophore at pH 2 and colour of the spots indicated that siderophores of Aspergillus sp. ABp4 and P. oxalicum and A. pullulans were trihydroxamates, whereas siderophore of P. chrysosporium was dihydroxamate. Amino acid composition of siderophores purified by XAD-2 column chromatography, revealed the presence of asparagine, histidine, and proline in Aspergillus sp. ABp4, serine and alanine in P. chrysosporium, and valine in M. africana. The structure of purified siderophores as revealed by NMR spectroscopy identified siderophore of AB - 2670 (A. pullulans) as asperchrome F1, and AB-513 (M. africana) as rhizoferrin. The peak obtained for siderophore AB-5 (Aspergillus sp. ABp4) did not show resemblance to any known siderophore, therefore may be an exception.

Bioleaching of copper from chalcopyrite ore by fungi.

Microorganisms have been geologically active in mineral formation, mineral diagenesis and sedimentation via direct action of their enzymes or indirectly through chemical action of their metabolic products. This property of microorganisms is being harnessed during the recent years for extraction of metals from their ores, especially from low-grade ores. In the present study bioleaching of copper from its low-grade chalcopyrite ore using 26 isolates of acidophilic fungi is reported. Most of these fungal strains belonged to the genera Aspergillus, Penicillium and Rhizopus. The leaching experiments were conducted in Czepek Dox minimal medium containing 1% (100 mesh) ore with shaking at room temperature for 20 days. Out of these, 4 isolates exhibited significant bioleaching activities. Maximum leaching of copper (78 mg/L) was observed with Aspergillus flavus (DSF-8) and Aspergillus niger (DOF-1). Nutritional and environmental conditions for optimum bioleaching were standardized. Present study indicates the usefulness of acidophilic fungi in bioleaching of copper from its low-grade ores.