ABSTRACT
Aspergillus terricola and Aspergillus ochraceus, isolated from Brazilian soil, were cultivated in Vogel and Adams media supplemented with 20 different carbon sources, at 30 degrees C, under static conditions, for 120 and 144 h, respectively. High levels of cellulase-free xylanase were produced in birchwood or oat spelt xylan-media. Wheat bran was the most favorable agricultural residue for xylanase production. Maximum activity was obtained at 60 degrees C and pH 6.5 for A. terricola, and 65 degrees C and pH 5.0 for A. ochraceus. A. terricola xylanase was stable for 1 h at 60 degrees C and retained 50% activity after 80 min, while A. ochraceus xylanase presented a t(50) of 10 min. The xylanases were stable in an alkali pH range. Biobleaching of 10 U/g dry cellulose pulp resulted in 14.3% delignification (A. terricola) and 36.4% (A. ochraceus). The brightness was 2.4-3.4% ISO higher than the control. Analysis in SEM showed defibrillation of the microfibrils. Arabinase traces and beta-xylosidase were detected which might act synergistically with xylanase.
Subject(s)
Aspergillus ochraceus/classification , Aspergillus ochraceus/enzymology , Cellulose/metabolism , Endo-1,4-beta Xylanases/chemistry , Endo-1,4-beta Xylanases/metabolism , Wood/chemistry , Endo-1,4-beta Xylanases/isolation & purification , Enzyme Activation , Enzyme Stability , Species SpecificityABSTRACT
Twelve hundred rice samples consisting of paddy (675) and milled rice (525) were collected from 20 states across India. These samples were assessed for Aspergillus spp. infection on selective medium and aflatoxin B(1) (AFB1) by indirect competitive ELISA. In this investigation, Aspergillus flavus contamination dominated in all the seed samples. The other major contaminants were Aspergillus niger, Aspergillus ochraceus and Aspergillus parasiticus. Out of 1200 rice samples, 67.8% showed AFB1 ranging from 0.1 to 308.0 microg/kg. All the paddy samples from Chattishgarh, Meghalaya and Tamil Nadu showed AFB1 contamination. Milled rice grains from different states showed below the permissible levels of AFB1 (average 0.5-3.5 microg/kg). Eighty-two percent of samples from open storage that were exposed to rain showed AFB1 contamination followed by one-year-old seed. Out of 1200 samples, 2% showed AFB1 contamination above the permissible limits (>30 microg/kg). This is the first comprehensive report of aflatoxin contamination in rice across 20 states in India.
Subject(s)
Aflatoxin B1/isolation & purification , Aspergillus/isolation & purification , Food Contamination/analysis , Oryza/microbiology , Aflatoxin B1/biosynthesis , Aspergillus/classification , Aspergillus/metabolism , Aspergillus flavus/classification , Aspergillus flavus/isolation & purification , Aspergillus flavus/metabolism , Aspergillus niger/classification , Aspergillus niger/isolation & purification , Aspergillus niger/metabolism , Aspergillus ochraceus/classification , Aspergillus ochraceus/isolation & purification , Aspergillus ochraceus/metabolism , Colony Count, Microbial/methods , Consumer Product Safety , Culture Media , Enzyme-Linked Immunosorbent Assay , Food Microbiology , India , Oryza/chemistry , Species SpecificityABSTRACT
The present study dealt with the decolorization and degradation of textile dye Reactive blue-25 (0.1gl(-1)) by mycelium of Aspergillus ochraceus NCIM-1146. Spectrophotometric and visual examinations showed that the decolorization was through fungal adsorption, followed by degradation. Shaking condition was found to be better for complete and faster adsorption (7h) and decolorization (20 days) of dye Reactive blue-25 (100mgl(-1)) as compared to static condition. Presence of glucose in medium showed faster adsorption (4h) and decolorization of dye from bound (7 days) mycelium. FTIR and GCMS analysis study revealed biodegradation of Reactive blue-25 into two metabolites phthalimide and di-isobutyl phthalate.
Subject(s)
Aspergillus ochraceus/metabolism , Coloring Agents/metabolism , Aspergillus ochraceus/classification , Biodegradation, Environmental , Culture Media , Hydrogen-Ion Concentration , Mycology/methods , Spectrophotometry, Atomic , TemperatureABSTRACT
Two PCR assays have been developed to detect Aspergillus carbonarius and Aspergillus ochraceus, considered the main sources of ochratoxin A (OTA) contaminating commodities, particularly grapes, coffee and derivatives, in warm climates. The species specific primers have been designed on the basis of ITS (internal transcribed spacers of rDNA units) sequence comparisons obtained from Aspergillus strains and have been tested in a number of strains from different origins and hosts. These PCR assays, based on multi-copy sequences, are highly sensitive and specific and represent a good tool for an early detection of OTA-producing Aspergillus species and to prevent OTA entering the food chain.
Subject(s)
Aspergillus ochraceus/isolation & purification , Aspergillus/classification , Aspergillus/isolation & purification , DNA, Ribosomal/analysis , Polymerase Chain Reaction/methods , Aspergillus/metabolism , Aspergillus ochraceus/classification , Aspergillus ochraceus/metabolism , Base Sequence , Food Contamination/analysis , Food Microbiology , Gene Amplification , Molecular Sequence Data , Ochratoxins/isolation & purification , Ochratoxins/metabolism , Phylogeny , Sequence Alignment , Species SpecificityABSTRACT
Ochratoxin A (OA) is a mycotoxin that has been found in coffee beans and coffee beverages. Its toxicological profile includes carcinogenicity, nephrotoxicity, and immunotoxicity. Aspergillus ochraceus is the major species responsible for OA production in Brazilian coffee beans. The genetic relationships among 25 A. ochraceus strains collected from Brazilian coffee-bean samples were determined based on RAPD and internal transcribed spacer (ITS) sequence data. The isolates were resolved into 2 distinct groups, one with 4 strains (group A) and the other with 21 strains (group B). Specific nucleotide variations characterizing group A and B were found for both ITS1 and ITS2 regions. Group B is a new group proposed here to accommodate the majority of the Brazilian isolates. Each group was found to contain both toxigenic and nontoxigenic strains, indicating that there is no association between molecular genotypes and the ability to produce OA.
Subject(s)
Aspergillus ochraceus/classification , Aspergillus ochraceus/genetics , DNA, Fungal/analysis , DNA, Ribosomal Spacer/analysis , Random Amplified Polymorphic DNA Technique/methods , Base Sequence , Brazil , Coffee/microbiology , Molecular Sequence Data , Ochratoxins/metabolism , Phylogeny , Sequence Analysis, DNAABSTRACT
70 strains of Aspergillus ochraceus mainly isolated from Brazilian coffee related sources were investigated for genetic relatedness using automated laser fluorescence analysis of AFLP fragments. Cluster analysis of fingerprints revealed a very close relationship among most of the strains. Based on these results, a sub-set of characteristic A. ochraceus strains was chosen for the detection of marker sequences. These sequences were obtained from silver stained AFLPs separated on polyacrylamide gels. A number of bands characteristic for A. ochraceus were detected and cut out from the gels. DNA was reamplified, cloned and fragments were sequenced. Based on these sequences a set of SCAR PCR-primers was constructed. PCRs were optimised for specificity and subsequently tested against a panel of Aspergillus species. Using this approach a PCR specific for Aspergillus ochraceus was developed.
Subject(s)
Aspergillus ochraceus/classification , Bacterial Typing Techniques/methods , DNA Fingerprinting/methods , DNA Primers , Polymerase Chain Reaction/methods , Polymorphism, Restriction Fragment Length , Aspergillus ochraceus/genetics , Aspergillus ochraceus/isolation & purification , Cloning, Molecular , Fluorescent Dyes/chemistry , Phylogeny , Sequence Analysis, DNA , Silver Staining/methods , Species SpecificityABSTRACT
Bilirubin dehydrogenase, a membrane-bound enzyme that catalyzes the one-step oxidation of ditaurobilirubin and bilirubin to ditaurobiliverdin and biliverdin, respectively, in the presence of an electron acceptor, was found in Aspergillus ochraceus IB-3, and purified from the membrane fraction through solubilization by Triton X-100. Phenazine and quinone derivatives acted as electron acceptors. Accumulation of ditaurobiliverdin and biliverdin by enzyme catalysis increased the absorbance at 660 nm, which is far from the range of wavelengths affected by serum ingredients. The enzyme selectively oxidized ditaurobilirubin at low pH, so changes in the reaction pH enable the enzyme to discriminate between the bilirubin fractions ditaurobilirubin (an example of conjugated bilirubin) and bilirubin (an example of unconjugated bilirubin). Using the enzyme, 2 to 80 microM of ditaurobilirubin were measured accurately by monitoring the changes in absorbance at 660 nm.
Subject(s)
Aspergillus ochraceus/enzymology , Bilirubin/analogs & derivatives , Bilirubin/analysis , Bilirubin/metabolism , Oxidoreductases/metabolism , Taurine/analogs & derivatives , Aspergillus ochraceus/classification , Benzoquinones/chemistry , Benzoquinones/pharmacology , Electrophoresis, Polyacrylamide Gel , Hydrogen-Ion Concentration , Methylphenazonium Methosulfate/analogs & derivatives , Methylphenazonium Methosulfate/pharmacology , Oxidation-Reduction , Oxidoreductases/drug effects , Spectrophotometry/methods , Substrate Specificity , Taurine/analysis , Taurine/metabolismABSTRACT
A new antibiotic, CJ-17,665 (I) was isolated from the fermentation broth of Aspergillus ochraceus, CL41582. It inhibits growth of multi-drug resistant Staphylococcus aureus, Streptococcus pyogenes, and Enterococcus faecalis, with MICs of 12.5, 12.5 and 25 microg/ml, respectively. The structure contains a diketopiperazine and an indole N-oxide moiety that is unusual in natural products.
