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Rhizopus Oryzae (rhizopus + oryzae)
Selected AbstractsMolecular characterization and antifungal activity of a family 46 chitosanase from Amycolatopsis sp.FEMS MICROBIOLOGY LETTERS, Issue 1 2009CsO- Abstract An actinomycete strain, Amycolatopsis sp. CsO-2, produces a 27-kDa chitosanase. To reveal the molecular characteristics of the enzyme, its corresponding gene ctoA was cloned by a reverse genetic technique, based on the N-terminal amino acid sequence of the protein. The encoded CtoA protein was deduced to be composed of 286 amino acids, including a putative signal peptide (1,48), and exhibited 83% identity in the amino acid sequence with the family 46 chitosanases from Streptomyces sp. N174 or Nocardioides sp. N106. The active recombinant CtoA protein was successfully overproduced in Escherichia coli. The mutant protein E22Q, in which the glutamic acid residue 22 was replaced with glutamine, abolished the chitosanase activity, showing that the Glu22 residue is required for the enzymatic activity. CtoA exhibited antifungal activity against Rhizopus oryzae, which is known to produce chitosan probably as a cell wall component. In contrast, E22Q did not inhibit the growth of the fungus, suggesting that chitosan-hydrolyzing activity is essential for the antifungal activity. It is noteworthy that the antifungal effect of CtoA against R. oryzae was drastically enhanced by the simultaneous addition of the family 19 chitinase ChiC from Streptomyces griseus. [source] Enhanced biocontrol activity of Trichoderma virens transformants constitutively coexpressing ,-1,3- and ,-1,6-glucanase genesMOLECULAR PLANT PATHOLOGY, Issue 4 2007SLAVICA DJONOVI SUMMARY Evidence for the role of chitinases, proteases and ,-1,3- and ,-1,6-glucanases in mycoparasitism by Trichoderma species has been well documented. Moreover, constitutive over-expression of genes encoding individual cell-wall-degrading enzymes (CWDEs) has been shown to improve the potential of biological agents. In this study, we generated transformants of T. virens in which ,-1,3- and ,-1,6-glucanase genes, TvBgn2 and TvBgn3, respectively, were constitutively coexpressed in the same genetic T. virens Gv29.8 wild-type background. The double over-expression transformants (dOEs) grow and sporulate slower than the wild-type (WT). However, the reduction in growth did not seem to affect their mycoparasitic and biocontrol capabilities, as dOEs displayed much higher levels of total ,-1,3- and ,-1,6-glucanase activity than the WT. This higher enzymatic activity of dOEs positively correlated with observed in vitro inhibition of Pythium ultimum and Rhizoctonia solani mycelia, and with enhanced bioprotection of cotton seedlings against P. ultimum, R. solani and Rhizopus oryzae. Besides effective biocontrol of all pathogens at an original inoculum level, the performance of dOEs was highly enhanced (up to 312% of WT performance) when pathogen pressure was greater (i.e. concentration of inoculum was higher or pathogens applied in combination). These results demonstrate that the strategy of introducing multiple lytic enzyme-encoding genes through transformation of a given biocontrol strain can be successfully used to achieve better biocontrol. [source] Interaction of amphotericin B lipid formulations and triazoles with human polymorphonuclear leucocytes for antifungal activity against ZygomycetesMYCOSES, Issue 2 2008Maria Simitsopoulou Summary The frequency of zygomycosis has increased considerably over recent years mainly in immunocompromised and diabetic patients. Little is known about the effects of host innate immunity against different Zygomycetes especially under the influence of antifungal agents. The antifungal activity of human polymorphonuclear leucocytes (PMN) in combination with liposomal amphotericin B (LAMB), amphotericin B lipid complex (ABLC), voriconazole (VRC) and posaconazole (PSC) against Rhizopus oryzae and Rhizopus microsporus, frequently isolated Zygomycetes, were studied and compared with Absidia corymbifera, a less pathogenic Zygomycete. Antifungal activity was evaluated as per cent of hyphal damage using the XTT metabolic assay. While A. corymbifera was more susceptible to PMN than the other two Zygomycetes, R. microsporus appeared to be the most susceptible to combined effects of amphotericin B formulations and VRC with PMN. LAMB exhibited synergistic activity with PMN in inducing hyphal damage to R. microsporus but not to the other fungi. In contrast, ABLC exhibited synergistic or additive activity with PMN against all three fungi. Among triazoles, only VRC exhibited additive effect with PMN against R. microsporus. Lipid formulations of amphotericin B and particularly ABLC interact with PMN predominantly in inducing augmented hyphal damage to three different species of Zygomycetes. [source] Zygomycosis , a case report and overview of the disease in IndiaMYCOSES, Issue 4 2007Amit Diwakar Summary A case of zygomycosis caused by Rhizopus oryzae in a diabetic patient previously misdiagnosed as invasive pulmonary aspergillosis and an overview of the disease in India are presented. The case was diagnosed by direct microscopy, histopathologic examination and culture. Following surgical resection of pulmonary cavity under cover of amphotericin B administration, the patient recovered completely. Of 461 cases reported to-date, approximately 70% had been diagnosed at the Postgraduate Institute of Medical Education and Research, Chandigarh, in north India. This may be attributed to better awareness, expertise and infrastructural facilities for mycological diagnosis than to any particular regional preponderance of the disease. Rhino-orbito-cerebral manifestations were the most common feature of zygomycosis (269 cases), followed by cutaneous disease (66 cases), which is in conformity with the pattern prevalent worldwide. The etiologic agents encountered were Rhizopus oryzae, Apophysomyces elegans, Saksenaea vasiformis, Cunninghamella bertholletiae, Absidia corymbifera, Basidiobolus ranarum and Conidiobolus coronatus. In contrast to cases from the developed world where transplant recipients and patients with haematological malignancies seem to be most vulnerable to zygomycosis, the most common risk factor in India was uncontrolled diabetes mellitus. Amphotericin B was the mainstay of various treatment modalities employed. The relevance of a strong clinical suspicion and early diagnosis of zygomycosis for favourable prognosis can hardly be over-emphasised. [source] Complete resolution of pulmonary Rhizopus oryzae infection with itraconazole treatment: more evidence of the utility of azoles for zygomycosisMYCOSES, Issue 3-4 2004D. P. Eisen Rhizopus oryzae; Zygomykose; Itraconazol Summary Zygomycosis often requires aggressive surgical and antifungal therapy. We report a non-neutropenic patient with myelodysplastic syndrome and iron overload receiving cytotoxic therapy who presented with pulmonary Rhizopus oryzae infection. This patient was cured through the use of itraconazole alone and the literature on the utility of azole antifungals for zygomycosis is reviewed. Zusammenfassung Die Zygomykosen erfordern aggressive chirurgische und antimykotische Therapie. Wir berichten über einen nicht-neutropenischen Patienten mit myelodysplastischem Syndrom und Eisenüberladung unter cytotoxischer Therapie, der eine pulmonale Rhizopus oryae Infektion entwick. Der Patient wurde durch Itraconazol geheilt. Es wird eine Literaturübersicht über den Wert von Azol-Antimykotika zur Zygomykose-Behandlung gegeben. [source] Production of L(+)-lactic acid from glucose and starch by immobilized cells of Rhizopus oryzae in a rotating fibrous bed bioreactorBIOTECHNOLOGY & BIOENGINEERING, Issue 1 2002Abdullatif Tay Abstract A rotating fibrous-bed bioreactor (RFB) was developed for fermentation to produce L(+)-lactic acid from glucose and cornstarch by Rhizopus oryzae. Fungal mycelia were immobilized on cotton cloth in the RFB for a prolonged period to study the fermentation kinetics and process stability. The pH and dissolved oxygen concentration (DO) were found to have significant effects on lactic acid productivity and yield, with pH 6 and 90% DO being the optimal conditions. A high lactic acid yield of 90% (w/w) and productivity of 2.5 g/L·h (467 g/h·m2) was obtained from glucose in fed-batch fermentation. When cornstarch was used as the substrate, the lactic acid yield was close to 100% (w/w) and the productivity was 1.65 g/L·h (300 g/h·m2). The highest concentration of lactic acid achieved in these fed-batch fermentations was 127 g/L. The immobilized-cells fermentation in the RFB gave a virtually cell-free fermentation broth and provided many advantages over conventional fermentation processes, especially those with freely suspended fungal cells. Without immobilization with the cotton cloth, mycelia grew everywhere in the fermentor and caused serious problems in reactor control and operation and consequently the fermentation was poor in lactic acid production. Oxygen transfer in the RFB was also studied and the volumetric oxygen transfer coefficients under various aeration and agitation conditions were determined and then used to estimate the oxygen transfer rate and uptake rate during the fermentation. The results showed that the oxygen uptake rate increased with increasing DO, indicating that oxygen transfer was limited by the diffusion inside the mycelial layer. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 80: 1,12, 2002. [source] High-affinity iron permease (FTR1) gene sequence-based molecular identification of clinically important ZygomycetesCLINICAL MICROBIOLOGY AND INFECTION, Issue 4 2008I. Nyilasi Abstract The clinical importance of zygomycosis, an emerging and frequently fatal mycotic disease, has increased during recent years. This report describes an identification method based on PCR amplification and sequencing of the high-affinity iron permease 1 gene (FTR1). Primers and amplification protocols were established and tested for the identification of Rhizopus oryzae, Rhizopus microsporus var. rhizopodiformis, R. microsporus var. oligosporus, Rhizopus schipperae, Rhizopus niveus and Rhizopus stolonifer. Rhizomucor and Syncephalastrum could be identified at the genus level. PCR,restriction fragment length polymorphism analysis of the amplified gene fragment using AluI digestion distinguished three subgroups among the R. oryzae isolates. [source] | |||||||||||||