Bisdechlorogeodin from antarctic Pseudogymnoascus sp. LAMAI 2784 for citrus canker control

AIMS

Citrus canker caused by Xanthomonas citri subsp. citri (X. citri) is a disease of economic importance. Control of this disease includes the use of metallic copper, which is harmful to the environment and human health. Previous studies showed that the crude extract from the fungus Pseudogymnoascus sp. LAMAI 2784 isolated from Antarctic soil had in vitro antibacterial action against X. citri. The aim of the present study was to expand the applications of this extract.

METHODS AND RESULTS

In greenhouse assays, the crude extract was able to reduce bacterial infection on citrus leaves from 1.55 lesions/cm2 (untreated plants) to 0.04 lesions/cm2. Bisdechlorogeodin was identified as the main compound of the bioactive fraction produced by Pseudogymnoascus sp. LAMAI 2784, which inhibited bacterial growth in vitro (IC90 ≈ 156 µg ml-1) and permeated 80% of X. citri cells, indicating that the membrane is the primary target.

CONCLUSION

The present results showed that the bioactive fraction of the extract is mainly composed of the compound bisdechlorogeodin, which is likely responsible for the biological activity against X. citri, and the main mechanism of action is the targeting of the cell membrane. This study indicates that bisdechlorogeodin has valuable potential for the control of X. citri.

Biobank of fungi from marine and terrestrial Antarctic environments

Harsh and extreme environments, such as Antarctica, offer unique opportunities to explore new microbial taxa and biomolecules. Given the limited knowledge on microbial diversity, this study aimed to compile, analyze and compare a subset of the biobank of Antarctic fungi maintained at the UNESP's Central of Microbial Resources (CRM-UNESP). A total of 711 isolates (240 yeasts and 471 filamentous fungi) from marine and terrestrial samples collected at King George Island (South Shetland Islands, Antarctica) were used with the primary objective of investigating their presence in both marine and terrestrial environments. Among the yeasts, 13 genera were found, predominantly belonging to the phylum Basidiomycota. Among the filamentous fungi, 34 genera were represented, predominantly from the phylum Ascomycota. The most abundant genera in the marine samples were Metschnikowia, Mrakia, and Pseudogymnoascus, while in the terrestrial samples, they were Pseudogymnoascus, Leucosporidium, and Mortierella. Most of the genera and species of the CRM-UNESP biobank of Antarctic fungi are being reported as an important target for biotechnological applications. This study showed the relevance of the CRM-UNESP biobank, highlighting the importance of applying standard methods for the preservation of the biological material and associated data (BMaD), as recommended in national and international standards.

Water-Soluble Glutamic Acid Derivatives Produced in Culture by Penicillium solitum IS1-A from King George Island, Maritime Antarctica

A new method of screening was developed to generate 770 organic and water-soluble fractions from extracts of nine species of marine sponges, from the growth media of 18 species of marine-derived fungi, and from the growth media of 13 species of endophytic fungi. The screening results indicated that water-soluble fractions displayed significant bioactivity in cytotoxic, antibiotic, anti-Leishmania, anti-Trypanosoma cruzi, and inhibition of proteasome assays. Purification of water-soluble fractions from the growth medium of Penicillium solitum IS1-A provided the new glutamic acid derivatives solitumine A (1), solitumine B (2), and solitumidines A-D (3-6). The structures of compounds 1-6 have been established by analysis of spectroscopic data, chemical derivatizations, and vibrational circular dichroism calculations. Although no biological activity could be observed for compounds 1-6, the new structures reported for 1-6 indicate that the investigation of water-soluble natural products represents a relevant strategy in finding new secondary metabolites.

Metal and organic pollutants bioremediation by extremophile microorganisms

Extremophiles comprise microorganisms that are able to grow and thrive in extreme environments, including in an acidic or alkaline pH, high or low temperatures, high concentrations of pollutants, and salts, among others. These organisms are promising for environmental biotechnology due to their unique physiological and enzymatic characteristics, which allow them to survive in harsh environments. Due to the stability and persistence of these microorganisms under adverse environmental conditions, they can be used for the bioremediation of environments contaminated with extremely recalcitrant pollutants. Here, we provide an overview of extremophiles and the role of "omics" in the field of bioremediation of environmental pollutants, including hydrocarbons, textile dyes and metals.

Pyrene degradation by marine-derived ascomycete: process optimization, toxicity, and metabolic analyses

Marine-derived fungi are relevant genetic resources for bioremediation of saline environments/processes. Among the five fungi recovered from marine sponges able to degrade pyrene (Py) and benzo[a]pyrene (BaP), Tolypocladium sp. strain CBMAI 1346 and Xylaria sp. CBMAI 1464 presented the best removal rates of Py and BaP, respectively. Since the decrease in BaP was related to mycelial adsorption, a combined strategy was applied for the investigation of Py degradation by the fungus Tolypocladium sp. CBMAI 1346. The selected fungus was able to degrade about 95% of Py after 7 days of incubation (optimized conditions), generating metabolites different from the ones found before optimization. Metabolites and transcriptomic data revealed that the degradation occurred mainly by the cytochrome P450 pathway. Putative monooxygenases and dioxygenases found in the transcriptome may play an important role. After 21 days of degradation, no toxicity was found in the optimized culture conditions. The findings from the present study highlight the potential of marine-derived fungi to degrade environmental pollutants and convey innovative information related to the metabolism of pyrene.

Biosurfactant production by yeasts from different types of soil of the South Shetland Islands (Maritime Antarctica)

AIM

To screen and identify a potential biosurfactant-producing yeast strain isolated from Antarctic soil and to evaluate the fermentation process kinetics of the most promising strain on biosurfactant production using glycerol as carbon source.

METHODS AND RESULTS

From the 68 isolated yeast strains, 11 strains were able to produce biosurfactants after Emulsification Index (E.I.) and Drop Collapse tests, reaching an E.I. higher than 10%. Strain 1_4.0 was the best producer, identified as Candida glaebosa based on molecular analysis. Yeast was cultivated in a medium composed of glycerol supplemented with yeast extract for 120 h to determine the process kinetics. The increased C/N ratio affected yeast growth and biosurfactant production. Biosurfactant release was associated with the end of exponential and beginning of the stationary growth phases. Results indicated an E.I. of 30% at the end of the fermentation.

CONCLUSIONS

The feasiability of C. glaebosa to produce biosurfactant from a low-cost medium cultivation shows a great impact on the development of bioresource in the Antarctica terrestrial environment.

SIGNIFICANCE AND IMPACT OF THE STUDY

Although the diversity of psychrophilic/psychrotolerant micro-organisms from Antarctica has been the preferred subject of study by microbiologists, terrestrial microfungal communities are scarcely investigated and literature about the biotechnological potential of such micro-organisms should cover important biomolecules in addition to cold-adapted enzymes. In the present study, for the first time, the Maritime Antarctica environment was screened as a novel source of biosurfactants produced by micro-organisms.

Polycyclic aromatic hydrocarbons degradation by marine-derived basidiomycetes: optimization of the degradation process

Pyrene and benzo[a]pyrene (BaP) are high molecular weight polycyclic aromatic hydrocarbons (PAHs) recalcitrant to microbial attack. Although studies related to the microbial degradation of PAHs have been carried out in the last decades, little is known about degradation of these environmental pollutants by fungi from marine origin. Therefore, this study aimed to select one PAHs degrader among three marine-derived basidiomycete fungi and to study its pyrene detoxification/degradation. Marasmiellus sp. CBMAI 1062 showed higher levels of pyrene and BaP degradation and was subjected to studies related to pyrene degradation optimization using experimental design, acute toxicity, organic carbon removal (TOC), and metabolite evaluation. The experimental design resulted in an efficient pyrene degradation, reducing the experiment time while the PAH concentration applied in the assays was increased. The selected fungus was able to degrade almost 100% of pyrene (0.08mgmL^-1) after 48h of incubation under saline condition, without generating toxic compounds and with a TOC reduction of 17%. Intermediate metabolites of pyrene degradation were identified, suggesting that the fungus degraded the compound via the cytochrome P450 system and epoxide hydrolases. These results highlight the relevance of marine-derived fungi in the field of PAH bioremediation, adding value to the blue biotechnology.

Activity of Antarctic fungi extracts against phytopathogenic bacteria

This study aims to obtain secondary metabolites extracts from filamentous fungi isolated from soil and marine sediments from Antarctic ecosystems and to assess its potential antibacterial activity on Xanthomonas euvesicatoria and Xanthomonas axonopodis pv. passiflorae (phytopathogenic bacteria causing diseases in pepper and tomato and passionfruit, respectively). Among the 66 crude intracellular and extracellular extracts obtained from fungi recovered from soil and 79 obtained from marine sediment samples, 25 showed the ability to prevent the growth of X. euvesicatoria in vitro and 28 showed the ability to prevent the growth of X. axonopodis pv. passiflorae in vitro. Intracellular and extracellular extracts from soil fungi inhibited around 97% of X. euvesicatoria and 98% of X. axonopodis pv. passiflorae at 2·1 mg ml^-1 . The average inhibition rates against X. euvesicatoria and X. axonopodis pv. passiflorae for intracellular and extracellular extracts from marine sediments fungi were around 96 and 97%, respectively, at 3·0 mg ml^-1 . Extracts containing secondary metabolites with antimicrobial activity against X. euvesicatoria and X. axonopodis pv. passiflorae were obtained, containing possible substitutes for the products currently used to control these phytopathogens.

SIGNIFICANCE AND IMPACT OF THE STUDY

Micro-organisms from extreme ecosystems, such as the Antarctic ecosystem, need to survive in harsh conditions with low temperatures, low nutrients and high UV radiation. Micro-organisms adapt to these conditions evolving diverse biochemical and physiological adaptations essential for survival. All this makes these micro-organisms a rich source of novel natural products based on unique chemical scaffolds. Discovering novel bioactive compounds is essential because of the rise in antibiotic-resistant micro-organisms and the emergence of new infections. Fungi from Antarctic environments have been proven to produce bioactive secondary metabolites against various micro-organisms, but few studies have shown activity against Xanthomonas phytopathogens.

Condensation of Macrocyclic Polyketides Produced by Penicillium sp. DRF2 with Mercaptopyruvate Represents a New Fungal Detoxification Pathway

Application of a refined procedure of experimental design and chemometric analysis to improve the production of curvularin-related polyketides by a marine-derived Penicillium sp. DRF2 resulted in the isolation and identification of cyclothiocurvularins 6-8 and cyclosulfoxicurvularins 10 and 11, novel curvularins condensed with a mercaptolactate residue. Two additional new curvularins, 3 and 4, are also reported. The structures of the sulfur-bearing curvularins were unambiguously established by analysis of spectroscopic data and by X-ray diffraction analysis. Analysis of stable isotope feeding experiments with [U-(13)C3(15)N]-l-cysteine confirmed the presence of the 2-hydroxy-3-mercaptopropanoic acid residue in 6-8 and the oxidized sulfoxide in 10 and 11. Cyclothiocurvularins A (6) and B (7) are formed by spontaneous reaction between 10,11-dehydrocurvularin (2) and mercaptopyruvate (12) obtained by transamination of cysteine. High ratios of [U-(13)C3(15)N]-l-cysteine incorporation into cyclothiocurvularin B (7), the isolation of two diastereomers of cyclothiocurvularins, the lack of cytotoxicity of cyclothiocurvularin B (7) and its methyl ester (8), and the spontaneous formation of cyclothiocurvularins from 10,11-dehydrocurvularin and mercaptopyruvate provide evidence that the formation of cyclothiocurvularins may well correspond to a 10,11-dehydrocurvularin detoxification process by Penicillium sp. DRF2.

Enhanced textile dye decolorization by marine-derived basidiomycete Peniophora sp. CBMAI 1063 using integrated statistical design

In the present study, the biotechnological potential of the marine-derived fungus Peniophora sp. CBMAI 1063 was investigated in relation to Reactive Black 5 (RB5) dye decolorization and degradation using an integrated statistical design composed of Plackett-Burman design (P&B), central composite design (CCD), and response surface methodology (RSM). RB5 dye was effectively decolorized (94 %) in saline conditions, without any detection of mutagenic compounds, and simultaneously, 57 % of total organic carbon (TOC) was removed in 7 days. The activity of lignin peroxidase (LiP) was not detected during the process. The gene expression of laccase (Lac) and manganese peroxidase (MnP) enzymes produced during the process was evaluated, and results from this experiment coupled with LC-MS analyses revealed that in the early stage of dye decolorization, a higher MnP gene expression and significant enzymatic activity was detected in Peniophora sp. CBMAI 1063 with the formation of p-Base and TAHNDS compounds. This paper reports innovative data related to the textile dye decolorization by the marine-derived basidiomycete Peniophora sp. CBMAI 1063, showing the metabolites formed and enzymatic action throughout the process in saline condition. The strategy used showed to be an efficient statistical approach that provides an attractive solution for the screening and simultaneous optimization of the degradation process.

Marine-derived fungus Aspergillus cf. tubingensis LAMAI 31: a new genetic resource for xylanase production

Marine-derived fungi have been reported as relevant producers of enzymes, which can have different properties in comparison with their terrestrial counterparts. The aim of the present study was to select from a collection of 493 marine-derived fungi the best producer of xylanase in order to evaluate the enzymatic production under different conditions. A total of 112 isolates produced xylanase in solid medium containing xylan as the carbon source, with 31 of them able to produce at least 10 U/mL of the enzyme. The best production (49.41 U/mL) was achieved by the strain LAMAI 31, identified as Aspergillus cf. tubingensis. After confirming the lack of pathogenicity (absence of ochratoxin A and fumonisin B₂ production) this fungus was submitted to the experimental design in order to evaluate the effect of different variables on the enzymatic production, with the aim of optimizing culture conditions. Three experimental designs (two Plackett–Burman and one factorial fractional) were applied. The best condition for the enzymatic production was defined, resulting in an increase of 12.7 times in comparison with the initial production during the screening experiments. In the validation assay, the peak of xylanase production (561.59 U/mL) was obtained after 96 h of incubation, being the best specific activity achieved after 72 h of incubation. Xylanase from A. cf. tubingensis LAMAI 31 had optimum pH and temperature at 5.0 and 55 °C, respectively, and was shown to be stable at a range of 40–50 °C, and in pH from 3.6 to 7.0. Results from the present work indicate that A. cf. tubingensis LAMAI 31 can be considered as a new genetic resource for xylanase production.

Stereoselective Bioreduction of α-Azido Ketones by Whole Cells of Marine-Derived Fungi

Seven strains of marine-derived fungi (Aspergillus sclerotiorum CBMAI 849, Cladosporium cladosporioides CBMAI 857, Penicillium raistrickii CBMAI 931, Penicillium citrinum CBMA 1186, Mucor racemosus CBMAI 847, Beauveria felina CBMAI 738, and Penicillium oxalicum CBMAI 1185) and terrestrial fungus Penicillium chrysogenum CBMA1199 were screened as catalysts for the asymmetric reduction of α-keto azides 5-8 to their corresponding β-azidophenylethanols 9-12. The marine fungi showed Prelog and anti-Prelog selectivities to the reduction α-keto azides 5-8. The fungi A. sclerotiorum CBMAI 849, C. cladosporioides CBMAI 857, P. raistrickii CBMAI 931, and P. citrinum CBMA 1186 catalyzed the reduction of azido ketone 6 to the corresponding (R)-2-azido-1-(4-methoxyphenyl)ethanol (10) with good conversions (68-100 %) and excellent enantiomeric excesses (>99 % ee) according to Prelog rule.

Structure and Biogenesis of Roussoellatide, a Dichlorinated Polyketide from the Marine-Derived Fungus Roussoella sp. DLM33

The structure of the fungal metabolite roussoellatide (1) has been established by spectroscopic and X-ray diffraction analyses. Results from feeding experiments with [1-(13)C]acetate, [2-(13)C]acetate, and [1,2-(13)C]acetate were consistent with a biosynthetic pathway to the unprecedented skeleton of 1 involving Favorskii rearrangements in separate pentaketides, subsequently joined via an intermolecular Diels-Alder reaction.

Marine-derived fungi: diversity of enzymes and biotechnological applications

The ocean is considered to be a great reservoir of biodiversity. Microbial communities in marine environments are ecologically relevant as intermediaries of energy, and play an important role in nutrient regeneration cycles as decomposers of dead and decaying organic matter. In this sense, marine-derived fungi can be considered as a source of enzymes of industrial and/or environmental interest. Fungal strains isolated from different substrates, such as invertebrates, decaying wood, seawater, sediments, and mangrove detritus, have been reported to be producers of hydrolytic and/or oxidative enzymes, with alginate lyase, amylase, cellulase, chitinase, glucosidase, inulinase, keratinase, ligninase, lipase, nuclease, phytase, protease, and xylanase being among the enzymes produced by fungi of marine origin. These enzymes present temperature and pH optima ranging from 35 to 70(∘)C, and 3.0 to 11.0, respectively. High-level production in bioreactors is mainly performed using submerged-state fermentation. Certain marine-derived fungal strains present enzymes with alkaline and cold-activity characteristics, and salinity is considered an important condition in screening and production processes. The adaptability of marine-derived fungi to oceanic conditions can be considered an attractive point in the field of fungal marine biotechnology. In this review, we focus on the advances in discovering enzymes from marine-derived fungi and their biotechnological relevance.

The marine-derived fungus Tinctoporellus sp. CBMAI 1061 degrades the dye Remazol Brilliant Blue R producing anthraquinones and unique tremulane sesquiterpenes

Conversion of RBBR dye to anthraquinones by the fungusTinctoporellussp., also producing novel tremulene terpenes.

Molecular diversity of fungal and bacterial communities in the marine sponge Dragmacidon reticulatum

The present work aimed to investigate the diversity of bacteria and filamentous fungi of southern Atlantic Ocean marine sponge Dragmacidon reticulatum using cultivation-independent approaches. Fungal ITS rDNA and 18S gene analyses (DGGE and direct sequencing approaches) showed the presence of representatives of three order (Polyporales, Malasseziales, and Agaricales) from the phylum Basidiomycota and seven orders belonging to the phylum Ascomycota (Arthoniales, Capnodiales, Dothideales, Eurotiales, Hypocreales, Pleosporales, and Saccharomycetales). On the other hand, bacterial 16S rDNA gene analyses by direct sequencing approach revealed the presence of representatives of seven bacterial phyla (Cyanobacteria, Proteobacteria, Actinobacteria, Bacteroidetes, Lentisphaerae, Chloroflexi, and Planctomycetes). Results from statistical analyses (rarefaction curves) suggested that the sampled clones covered the fungal diversity in the sponge samples studied, while for the bacterial community additional sampling would be necessary for saturation. This is the first report related to the molecular analyses of fungal and bacterial communities by cultivation-independent approaches in the marine sponges D. reticulatum. Additionally, the present work broadening the knowledge of microbial diversity associated to marine sponges and reports innovative data on the presence of some fungal genera in marine samples.

Two Polyketides from a Co-culture of Two Marine-derived Fungal Strains

Co-cultivation of the fungal strains Penicillium sp. Ma(M3)V and Trichoderma sp. Gc(M2)1 in malt 2% medium led to the production of two novel, unusual polyketides, ( Z)-2-ethylhex-2-enedioic acid and ( E)-4-oxo-2-propylideneoct-7-enoic acid. Analysis of spectroscopic data enabled the structure determination of both compounds.

Fungal communities in the garden chamber soils of leaf-cutting ants

Leaf-cutting ants modify the properties of the soil adjacent to their nests. Here, we examined whether such an ant-altered environment impacts the belowground fungal communities. Fungal diversity and community structure of soil from the fungus garden chambers of Atta sexdens rubropilosa and Atta bisphaerica, two widespread leaf-cutting ants in Brazil, were determined and compared with non-nest soils. Culture-dependent methods revealed similar species richness but different community compositions between both types of soils. Penicillium janthinellum and Trichoderma spirale were the prevalent isolates in fungus chamber soils and non-nest soils, respectively. In contrast to cultivation methods, analyses of clone libraries based on the internal transcribed spacer (ITS) region indicated that richness of operational taxonomic units significantly differed between soils of the fungus chamber and non-nest soils. FastUnifrac analyses based on ITS sequences further revealed a clear distinction in the community structure between both types of soils. Plectania milleri and an uncultured Clavariaceae fungus were prevalent in fungus chamber soils and non-nest soils, respectively. FastUnifrac analyses also revealed that fungal community structures of soil from the garden chambers markedly differed among ant species. Our findings suggest that leaf-cutting ants affect fungal communities in the soil from the fungus chamber in comparison to non-nest soils.

Sustainable production of biologically active molecules of marine based origin

The marine environment offers both economic and scientific potential which are relatively untapped from a biotechnological point of view. These environments whilst harsh are ironically fragile and dependent on a harmonious life form balance. Exploitation of natural resources by exhaustive wild harvesting has obvious negative environmental consequences. From a European industry perspective marine organisms are a largely underutilised resource. This is not due to lack of interest but due to a lack of choice the industry faces for cost competitive, sustainable and environmentally conscientious product alternatives. Knowledge of the biotechnological potential of marine organisms together with the development of sustainable systems for their cultivation, processing and utilisation are essential. In 2010, the European Commission recognised this need and funded a collaborative RTD/SME project under the Framework 7-Knowledge Based Bio-Economy (KBBE) Theme 2 Programme 'Sustainable culture of marine microorganisms, algae and/or invertebrates for high value added products'. The scope of that project entitled 'Sustainable Production of Biologically Active Molecules of Marine Based Origin' (BAMMBO) is outlined. Although the Union is a global leader in many technologies, it faces increasing competition from traditional rivals and emerging economies alike and must therefore improve its innovation performance. For this reason innovation is placed at the heart of a European Horizon 2020 Strategy wherein the challenge is to connect economic performance to eco performance. This article provides a synopsis of the research activities of the BAMMBO project as they fit within the wider scope of sustainable environmentally conscientious marine resource exploitation for high-value biomolecules.

Filamentous fungi from the Atlantic marine sponge Dragmacidon reticulatum

Dragmacidon reticulatum is a marine sponge of wide occurrence in the Eastern and Western Atlantic. Little is known about D. reticulatum fungal diversity. Filamentous fungi recovered from D. reticulatum were assessed in the present study using a polyphasic taxonomic approach, including classical morphology, molecular biology and MALDI-TOF ICMS. Ninety-eight fungal strains were isolated from two D. reticulatum samples by using six different culture media, which were identified up to the genus level. Sixty-four distinct fungal ribotypes were obtained, distributed among twenty-four different genera belonging to the Ascomycota and Zygomycota. Representatives of Penicillium and Trichoderma were the most diverse and abundant fungi isolated. Amongst Penicillium spp. three isolates belonged to the same ribotype can be considered as a putative new species. Data derived from the present study highlight the importance of using a polyphasic approach to get an accurate identification in order to structure a reliable culture collection.

Stereoselective bioreduction of 1-(4-methoxyphenyl)ethanone by whole cells of marine-derived fungi

Nine strains of marine-derived fungi (Aspergillus sydowii Ce15, A. sydowii Ce19, Aspergillus sclerotiorum CBMAI 849, Bionectria sp. Ce5, Beauveria felina CBMAI 738, Cladosporium cladosporioides CBMAI 857, Mucor racemosus CBMAI 847, Penicillium citrinum CBMAI 1186, and Penicillium miczynskii Gc5) were screened, catalyzing the asymmetric bioreduction of 1-(4-methoxyphenyl)ethanone 1 to its corresponding 1-(4-methoxyphenyl)ethanol 2. A. sydowii Ce15 and Bionectria sp. Ce5 produced the enantiopure (R)-alcohol 2 (>99% ee) in accordance with the anti-Prelog rule and, the fungi B. felina CBMAI 738 (>99% ee) and P. citrinum CBMAI 1186 (69% ee) in accordance with the Prelog rule. Stereoselective bioreduction by whole cells of marine-derived fungi described by us is important for the production of new reductases from marine-derived fungi.

Selection of thermophilic and thermotolerant fungi for the production of cellulases and xylanases under solid-state fermentation

Twenty-seven thermophilic and thermotolerant fungal strains were isolated from soil, decaying organic matter and sugarcane piles based on their ability to grow at 45°C on medium containing corn straw and cardboard as carbon sources. These fungi were identified in the genera Aspergillus, Thermomyces, Myceliophthora, Thermomucor and Candida. The majority of the isolated strains produced xylanase and cellulases under solid state fermentation (SSF). The highest cellulase and xylanase productions were obtained by the cultivation of the strains identified as Aspergillus fumigatus M.7.1 and Myceliophthora thermophila M.7.7. The enzymes from these strains exhibited maximum activity at pH 5.0 and at 60 and 70ºC. The endo-glucanase from A. fumigatus was stable from 40°C to 65°C and both endo-glucanase and xylanase from M. thermophila were stable in this temperature range when in absence of substrate. The enzymes were stable from pH 4.0 to 9.0.

Molecular analysis of microbial diversity in corrosion samples from energy transmission towers

Microbial diversity in corrosion samples from energy transmission towers was investigated using molecular methods. Ribosomal DNA fragments were used to assemble gene libraries. Sequence analysis indicated 10 bacterial genera within the phyla Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes. In the two libraries generated from corroded screw-derived samples, the genus Acinetobacter was the most abundant. Acinetobacter and Clostridium spp. dominated, with similar percentages, in the libraries derived from corrosion scrapings. Fungal clones were affiliated with 14 genera belonging to the phyla Ascomycota and Basidiomycota; of these, Capnobotryella and Fellomyces were the most abundant fungi observed. Several of the microorganisms had not previously been associated with biofilms and corrosion, reinforcing the need to use molecular techniques to achieve a more comprehensive assessment of microbial diversity in environmental samples.

Marine-derived filamentous fungi and their potential application for polycyclic aromatic hydrocarbon bioremediation

Eight marine-derived fungi that were previously selected for their abilities to decolorize RBBR dye were subjected to pyrene and benzo[a]pyrene degradation. The fungus Aspergillus sclerotiorum CBMAI 849 showed the best performance with regard to pyrene (99.7%) and benzo[a]pyrene (76.6%) depletion after 8 and 16 days, respectively. Substantial amounts of benzo[a]pyrene (>50.0%) depletion were also achieved by Mucor racemosus CBMAI 847. Therefore, these two fungal strains were subjected to metabolism evaluation using the HPLC-DAD-MS technique. The results showed that A. sclerotiorum CBMAI 849 and M. racemosus CBMAI 847 were able to metabolize pyrene to the corresponding pyrenylsulfate and were able to metabolize benzo[a]pyrene to benzo[a]pyrenylsulfate, suggesting that the mechanism of hydroxylation is mediated by a cytochrome P-450 monooxygenase, followed by conjugation with sulfate ions. Because these fungi were adapted to the marine environment, the strains that were used in the present study are considered to be attractive targets for the bioremediation of saline environments, such as ocean and marine sediments that are contaminated by PAHs.

Use of experimental design for the optimization of the production of new secondary metabolites by two Penicillium species

A fractional factorial design approach has been used to enhance secondary metabolite production by two Penicillium strains. The method was initially used to improve the production of bioactive extracts as a whole and subsequently to optimize the production of particular bioactive metabolites. Enhancements of over 500% in secondary metabolite production were observed for both P. oxalicum and P. citrinum. Two new alkaloids, citrinalins A (5) and B (6), were isolated and identified from P. citrinum cultures optimized for production of minor metabolites.

Microbial diversity associated with algae, ascidians and sponges from the north coast of São Paulo state, Brazil

Little is known about the microbial diversity associated with marine macroorganisms, despite the vital role microorganisms may play in marine ecosystems. The aim of the present study was to investigate the diversity of bacteria and fungi isolated from eight marine invertebrate and one algae samples. Data derived from ARDRA and sequencing analyses allowed the identification of marine-derived microorganisms isolated from those samples. Microbial strains identified up to the genus level revealed 144 distinct ribotypes out of 256 fungal strains and 158 distinct ribotypes out of 181 bacterial strains. Filamentous fungi were distributed among 24 different genera belonging to Ascomycota, Zygomycota and Basidiomycota, some of which had never been reported in the literature as marine invertebrate-inhabiting fungi (Pestalotiopsis, Xylaria, Botrysphaeria and Cunnninghamella). Bacterial isolates were affiliated to 41 different genera, being Bacillus, Ruegeria, Micrococcus, Pseudovibrio and Staphylococcus the most abundant ones. Results revealed an unexpected high microbial diversity associated to the macroorganisms which have been collected and suggested the selection of certain microbial taxonomic groups according to the host. The combined data gathered from this investigation contribute to broaden the knowledge of microbial diversity associated to marine macroorganisms, including as a promising source for the discovery of new natural products.

Pectinase production by a Brazilian thermophilic fungus Thermomucor indicae-seudaticae N31 in solid-state and submerged fermentation

Thermophilic organisms produce thermostable enzymes, which have a number of applications, justifying the interest in the isolation of new thermophilic strains and study of their enzymes. Thirty-four thermophilic and thermotolerant fungal strains were isolated from soil, organic compost, and an industrial waste pile based on their ability to grow at 45 degrees C and in a liquid medium containing pectin as the only carbon source. Among these fungi, 50% were identified at the genus level as Thermomyces, Aspergillus, Monascus, Chaetomium, Neosartoria, Scopulariopsis, and Thermomucor. All isolated strains produced pectinase during solid-state fermentation (SSF). The highest polygalacturonase (PG) activity was obtained in the culture medium of thermophilic strain N31 identified as Thermomucor indicae-seudaticae. Under SSF conditions on media containing a mixture of wheat bran and orange bagasse (1:1) at 70% of initial moisture, this fungus produced the maximum of 120 U/ml of exo-PG, while in submerged fermentation (SmF) it produced 13.6 U/ml. The crude PG from SmF was more thermostable than that from SSF and exhibited higher stability in acidic pH.

Cnidarian-derived filamentous fungi from Brazil: isolation, characterisation and RBBR decolourisation screening

Marine-derived fungi represent a valuable source of structurally novel and biologically active metabolites of industrial interest. They also have drawn attention for their capacity to degrade several pollutants, including textile dyes, organochlorides and polycyclic aromatic hydrocarbons (PAHs), among others. The fungal tolerance to higher concentrations of salt might be considered an advantage for bioremediation processes in the marine environment. Therefore, filamentous fungi were isolated from cnidarians (scleractinian coral and zoanthids) collected from the north coast of São Paulo State, Brazil. A total of 144 filamentous fungi were morphologically and molecularly characterised. Among them there were several species of Penicillium and Aspergillus, in addition to Cladosporium spp., Eutypella sp., Fusarium spp., Khuskia sp., Mucor sp., Peacilomyces sp., Phoma sp. and Trichoderma spp. These fungi were tested regarding their decolourisation activity for Remazol Brilliant Blue R (RBBR), a textile dye used as an initial screening for PAH-degrading fungi. The most efficient fungi for RBBR decolourisation after 12 days were Penicillium citrinum CBMAI 853 (100%), Aspergillus sulphureus CBMAI 849 (95%), Cladosporium cladosporioides CBMAI 857 (93%) and Trichoderma sp. CBMAI 852 (89%). Besides its efficiency for dye decolourisation within liquid media, C. cladosporioides CBMAI 857 also decolourised dye on solid media, forming a decolourisation halo. Further research on the biotechnological potential, including studies on PAH metabolism, of these selected fungi are in progress.

Microbial lignocellulolytic enzymes: industrial applications and future perspectives

The demand for microbial industrial enzymes is ever increasing due to their use in a wide variety of processes. Lignocellulolytic enzymes have potential applications in a large number of fields, including the chemical, fuel, food, agricultural, paper, textile and cosmetic industrial sectors. Lignocellulosic biomass is an abundant renewable resource composed of cellulose (a polymer of glucose that represents the major fraction of lignocellulose), hemicellulose (also a sugar polymer) and lignin (a complex phenylpropane polymer). Lignocellulosic material can be broken down by microorganisms into its sugar components, thereby providing a readily fermentable substrate. One of the most significant potential applications of lignocellulolytic enzymes is fuel production from agricultural and forest wastes as an alternative renewable energy resource. The need to reduce carbon dioxide emissions provides an additional incentive for the development of processes for production of fuels from lignocellulosic biomass and has attracted the interest of biotechnologists and microbiologists in recent decades.

New destruxins from the marine-derived fungus Beauveria felina

Chemical investigation of the cytotoxic and anti-tuberculosis active butanone extract obtained from the growth media of the marine-derived fungus Beauveria felina led to the isolation of two new destruxins, [beta-Me-Pro] destruxin E chlorohydrin (1) and pseudodestruxin C (3), along with five known cyclic depsipeptides. The structures of the new destruxin derivatives were established by analysis of spectroscopic data, while the absolute configuration of the common amino acid residues was established by Marfey's analysis. The absolute configuration of the 2(R),4(S)-5-chloro-2,4-dihydroxypentanoic acid residue in 1 could be established by application of a J-based configuration method followed by derivatization with R-MPA-Cl and NMR analysis.

Analysis of the composition of bacterial communities in oil reservoirs from a southern offshore Brazilian basin

The aim of this study was to characterize and compare the bacterial community structure of two distinct oil samples from a petroleum field in Brazil by using both molecular, based on the construction of 16S rRNA gene libraries, and cultivation methods. Statistical comparisons of libraries based on Amplified Ribosomal DNA Restriction Analysis (ARDRA) data revealed no significant differences between the communities recovered in the non-biodegraded (NBD) and highly biodegraded oils (HBD). BlastN analysis of the 16S rRNA gene sequences representative of distinct ribotypes from both oils showed the presence of nine different bacterial genera in these samples, encompassing members of the genera Arcobacter, Halanaerobium, Marinobacter, Propionibacterium, Streptomyces, Leuconostoc, Acinetobacter, Bacillus and Streptococcus. Enrichments obtained using oil as inoculum and sole carbon source yielded bacterial isolates showing high 16S rRNA gene sequence similarity with Achromobacter xylosoxidans, Bacillus subtilis, Brevibacillus sp., Dietzia sp. and Methylobacterium sp. Comparison between the data obtained using cultivation-independent and enrichment cultures suggests that different selection of community members may occur when using distinct approaches. All the organisms found, except for Leuconostoc sp. and Streptococus sp., have been previously reported in the literature as hydrocarbon degraders and/or associated to oil field environments.

Isolation and characterization of alachlor-degrading actinomycetes from soil

Alachlor (2-cloro-N-(methoxymethyl)-N-(2,6-diethylphenyl)-acetamide) is an extremely toxic and highly mobile herbicide that is widely used for pre-emergence control of grasses and weeds in many commercial crops in Brazil. In order to select soil actinomycetes able to degrade this herbicide, fifty-three actinomycete strains were isolated from soil treated with alachlor using selective conditions and subjected to in vitro degradation assays. Sixteen isolates were shown to be tolerant to high concentrations of the herbicide (up to 720 mg L(-1)), and six of these were able to grow and degrade >/= 50 alachlor (72 mg L(-1)) in mineral salts medium. Morphological and phylogenetic analysis enabled the assignment of the alachlor-degrading strains to the genus Streptomyces. Strain LS151 was related to the type strains of Streptomyces capoamus/Streptomyces galbus, whereas strains LS143 and LS153 were related to Streptomyces bikiniensis. The remaining strains, LS166, LS177 and LS182, were similar in morphological features and recovered in a single cluster based on 16S rDNA sequence analysis, but shown to be distinct on the basis of genomic fingerprint data (rep-PCR). Though a definitive taxonomic assignment of alachlor-degrading strains was not possible, these data indicate that ability to degrade this pesticide was detected in different Streptomyces taxa.