Improvement of the alkali stability of Penicillium cyclopium lipase by error-prone PCR

BACKGROUND: Lipases are extensively exploited in lots of industrial fields; cold-adapted lipases with alkali-resistance are especially desired in detergent industry. Penicillium cyclopium lipase I (PCL) might be suitable for applications of detergent industry due to its high catalytic efficiency at low temperature and relatively good alkali stability. In this study, to better meet the requirements, the alkali stability of PCL was further improved via directed evolution with error-prone PCR. RESULTS: The mutant PCL (N157F) with an improved alkali stability was selected based on a high-throughput activity assay. After incubating at pH 11.0 for 120 min, N157F retained 70% of its initial activity, which was 23% higher than that of wild type PCL. Combined with the three-dimensional structure analysis, N157F exhibited an improved alkali stability under the high pH condition due to the interactions of hydrophilicity and ß-strand propensity. Conclusions: This work provided the theoretical foundation and preliminary data for improving alkali stability of PCL to meet the industrial requirements, which is also beneficial to improving alkali-tolerance ability of other industrial enzymes via molecular modification.

Pectin lyase overproduction by Penicillium griseoroseum mutants resistant to catabolite repression

Abstract Expression of pectinolytic genes is regulated by catabolic repression limiting the production of pectin lyase (PL) if the natural inducer, pectin, is missing from the growth medium. Here, we report the isolation of Penicillium griseoroseum mutants resistant to 2-deoxy-d-glucose (DG) that show resistance to catabolite repression and overproduce PL. Three spontaneous and nine UV-induced mutants were obtained. Some mutants produced sectors (segments morphologically different) that were also studied. The mutants were analyzed for pectinases production on pectinase-agar plates and five mutants and two sectors showing larger clearing zones than the wild type were selected for quantitative assay. Although PL production higher than the wild type has been found, phenotype instability was observed for most of the mutants and, after transfers to nonselective medium, the DG resistance was no longer present. Only mutants M03 and M04 were stable maintaining the DG-resistance phenotype. When growing for 120 h in liquid medium containing glucose with or without pectin, both mutants showed higher PL production. In the presence of glucose as sole carbon source, the mutant M03 produced 7.8-fold more PL than the wild type. Due its phenotypic stability and PL overproduction, the mutant M03 presents potential for industrial applications.

Biodegradation of kerosene: Study of growth optimization and metabolic fate of P. janthinellum SDX7

Penicillum janthinellum SDX7 was isolated from aged petroleum hydrocarbon-affected soil at the site of Anand, Gujarat, India, and was tested for different pH, temperature, agitation and concentrations for optimal growth of the isolate that was capable of degrading upto 95%, 63% and 58% of 1%, 3% and 5% kerosene, respectively, after a period of 16 days, at optimal growth conditions of pH 6.0, 30 °C and 180 rpm agitation. The GC/MS chromatograms revealed that then-alkane fractions are easily degraded; however, the rate might be lower for branched alkanes, n-alkylaromatics, cyclic alkanes and polynuclear aromatics. The test doses caused a concentration-dependent depletion of carbohydrates of P. janthinellum SDX7 by 3% to 80%, proteins by 4% to 81% and amino acids by 8% to 95% upto 16 days of treatment. The optimal concentration of 3% kerosene resulted in the least reduction of the metabolites of P. janthinellum such as carbohydrates, proteins and amino acids with optimal growth compared to 5% and 1% (v/v) kerosene doses on the 12th and 16th day of exposure. Phenols were found to be mounted by 43% to 66% at lower and higher concentrations during the experimental period. Fungal isolate P. janthinellum SDX7 was also tested for growth on various xenobiotic compounds.

Disseminated Penicilliosis in a Korean Human Immunodeficiency Virus Infected Patient from Laos

Penicillium marneffei may cause life-threatening systemic fungal infection in immune-compromised patients and it is endemic in Southeast Asia. A 39-yr-old HIV-infected male, living in Laos, presented with fever, cough, and facial vesiculopapular lesions, which had been apparent for two weeks. CT scans showed bilateral micronodules on both lungs; Pneumocystis jirovecii was identified by bronchoscopic biopsy. Despite trimethoprim-sulfamethoxazole and anti-tuberculosis medications, the lung lesions progressed and the facial lesions revealed central umbilications. Biopsy of the skin lesions confirmed disseminated penicilliosis, with the culture showing P. marneffei hyphae and spores. The P. marneffei was identified by rRNA PCR. A review of the bronchoscopic biopsy indicated penicilliosis. The patient completely recovered after being prescribed amphotericin-B and receiving antiretroviral therapy. This is the first case of penicilliosis in a Korean HIV-infected patient. It is necessary to consider P. marneffei when immunocompromised patients, with a history of visits to endemic areas, reveal respiratory disease.

A Case of Disseminated Penicillium marneffei Infection in a Liver Transplant Recipient / 대한진단검사의학회지

Penicillium marneffei is the only dimorphic fungus among Penicillium spp. that can cause a fatal infection in immunocompromised patients. P. marneffei is endemic in Southeast Asia and eastern China. P. marneffei infection is an AIDS-defining illness and the third most common opportunistic infection in the endemic regions. Here, the authors report a case of disseminated P. marneffei infection in a patient who underwent liver transplantation in China. During the hospital stay, the mold form of the fungus that produced a red wine-colored pigment on the agar plate was isolated from the patient's urine, transtracheal aspirate, and blood. The fungus was identified as P. marneffei by direct sequencing of the D1-D2 and ITS regions. Thermal dimorphism was also confirmed by subculturing the colony at 37degrees C. To the best of our knowledge, this is the first Korean case of disseminated P. marneffei infection in a liver transplant recipient.

Gel mobility shift scanning of pectin-inducible promoter from Penicillium griseoroseum reveals the involvement of a CCAAT element in the expression of a polygalacturonase gene

Previous reports have described pgg2, a polygalacturonase-encoding gene of Penicillium griseoroseum, as an attractive model for transcriptional regulation studies, due to its high expression throughout several in vitro growth conditions, even in the presence of non-inducing sugars such as sucrose. A search for regulatory motifs in the 5' upstream regulatory sequence of pgg2 identified a putative CCAAT box that could justify this expression profile. This element, located 270 bp upstream of the translational start codon, was tested as binding target for regulatory proteins. Analysis of a 170 bp promoter fragment by electrophoretic mobility shift assay (EMSA) with nuclear extracts prepared from mycelia grown in pectin-containing culture medium revealed a high mobility complex that was subsequently confirmed by analyzing it with a double-stranded oligonucleotide spanning the CCAAT motif. A substitution in the core sequence for GTAGG partially abolished the formation of specific complexes, showing the involvement of the CCAAT box in the regulation of the polygalacturonase gene studied.

Actividades hidrolíticas y caracterización isoenzimática de poblaciones microbianas aisladas del patrimonio documental del Archivo General de Colombia / Hydrolytic activity and isoenzymatic characterization of microbial population Isolated of documental Heritage of General Archive of Colombia (AGN)

Este trabajo presenta un modelo para el aislamiento y evaluación de microorganismos agentes deteriorantes del acervo documental. Se recuperaron e identificaron 28 aislamientos tanto de las unidades de conservación con biodeterioro como de la atmósfera del depósito 15 del Archivo General de la Nación de Colombia (AGN). De este grupo, 16 aislamientos microbianos mostraron capacidad hidrolítica sobre fibras vegetales cuando se cultivaron en medios con paredes celulares al 1porciento como única fuente de carbono. A las poblaciones microbianas recuperadas se les evaluó su capacidad para hidrolizar celulosa, xilano, almidón y proteínas, considerando los halos de degradación y el número de sustratos hidrolizados, se seleccionaron cuatro aislamientos: dos de Penicillium sp., uno de Bacillus sp. y uno de Actinopolyspora sp. A los aislamientos se les cuantificó las actividades depolimerasas y accesorias y se les determinó el perfil isoenzimático para celulasas y xilanasas. Los resultados sugieren: (i) los hongos filamentosos y actinomycetes son más eficientes en la degradación de polímeros complejos, (ii) posiblemente las poblaciones bacterianas actúan como colonizadores secundarios y (iii) el perfil isoenzimático permite descartar microorganismos saprófitos, de especializados en degradar soporte celulolítico

Easy detection of green fluorescent protein multicopy transformants in Penicillium griseoroseum

Penicillium griseoroseum, a deuteromycete fungus producer of pectinolytic enzymes, was transformed with a gene encoding for green fluorescent protein (GFP). The selection of transformants was based on the homologous nitrate reductase gene (niaD). Protoplasts of a P. griseoroseum Nia mutant (PG63) were co-transformed with the plasmids pNPG1 and pAN52-1-GFP. The plasmid pNPG-1 carries the homologous niaD gene and pAN52-1-GFP carries the SGFP-TYG version of GFP. The highest transformation efficiency (102 transformants/µg of pNPG1) resulted from the utilization of equimolar amounts of transforming and co-transforming vectors. Analysis of pAN52-1-GFP insertions into the genomic DNA of the transformants revealed single and multiple copy integrations. The transformants possessing a single copy of the gfp gene showed a low level of fluorescence, whereas multicopy transformants displayed strong fluorescence under visualization with fluorescent light. The transformants showing high expression of the gfp gene had the normal mycelia pigmentation altered, displaying a bright green-yellowish color, visible with the naked eye on the plates, without the aid of any kind of fluorescent light or special filter set.