Semi-continuous production of the anticancer drug taxol by Aspergillus fumigatus and Alternaria tenuissima immobilized in calcium alginate beads.

Taxol is the most profitable drug ever developed in cancer chemotherapy; however, the market demand for the drug greatly exceeds the supply that can be sustained from its natural sources. In this study, Aspergillus fumigatus TXD105-GM6 and Alternaria tenuissima TER995-GM3 were immobilized in calcium alginate beads and used for the production of taxol in shake flask cultures. In an effort to increase the taxol magnitude, immobilization conditions were optimized by response surface methodology program (RSM). The optimum levels of alginate concentration, calcium chloride concentration, and mycelium fresh weight were 5%, 4%, and 15% (w/v), respectively. Under these conditions, taxol production by the respective fungal strains was intensified to 901.94 µg L-1 and 529.01 µg L-1. Moreover, the immobilized mycelia of both strains were successfully used in the repeated production of taxol for six different fermentation cycles. The total taxol concentration obtained in all cycles reached 4540.14 µg L-1 by TXD105-GM6 and 2450.27 µg L-1 by TER995-GM3 strain, which represents 7.85- and 6.31-fold increase, as compared to their initial titers. This is the first report on the production of taxol in semi-continuous fermentation. To our knowledge, the taxol productivity achieved in this study is the highest reported by academic laboratories for microbial cultures which indicates the future possibility to reduce the cost of taxol production.

Strain improvement and immobilization technique for enhanced production of the anticancer drug paclitaxel by Aspergillus fumigatus and Alternaria tenuissima.

UV and gamma irradiation mutagenesis was applied on Aspergillus fumigatus and Alternaria tenuissima in order to improve their producing ability of paclitaxel. Among the screened mutants, two stable strains (designated TXD105-GM6 and TER995-GM3) showed the maximum paclitaxel production. Paclitaxel titers of the two respective mutants were dramatically intensified to 1.22- and 1.24-fold, as compared by their respective parents. Immobilization using five different entrapment carriers of calcium alginate, agar-agar, Na-CMC, gelatin, and Arabic gum was successfully applied for production enhancement of paclitaxel by the two mutants. The immobilized cultures were superior to free-cell cultures and paclitaxel production by the immobilized mycelia was much higher than that of the immobilized spores using all the tried carriers. Moreover, calcium alginate gel beads were found the most conductive and proper entrapment carrier for maximum production of paclitaxel. The feasibility of the paclitaxel production by the immobilized mycelia as affected by incubation period, medium volume, and number of beads per flask was adopted. Under the favorable immobilization conditions, the paclitaxel titers were significantly intensified to 1.31- and 1.88-fold by the respective mutants, as compared by their free cultures. The obtained paclitaxel titers by the immobilized mycelia of the respective mutants (694.67 and 388.65 µg L-1) were found promising in terms of fungal production of paclitaxel. Hence, these findings indicate the future possibility to reduce the cost of producing paclitaxel and suggest application of the immobilization technique for the biotechnological production of paclitaxel at an industrial scale.

Production of paclitaxel with anticancer activity by two local fungal endophytes, Aspergillus fumigatus and Alternaria tenuissima.

Among 60 fungal endophytes isolated from twigs, bark, and mature leaves of different plant species, two fungal isolates named TXD105 and TER995 were capable of producing paclitaxel in amounts of up to 84.41 and 37.92 µg L-1, respectively. Based on macroscopic and microscopic characteristics, ITS1-5.8S-ITS2 rDNA sequence, and phylogenetic characteristic analysis, the two respective isolates were identified as Aspergillus fumigatus and Alternaria tenuissima. In the effort to increase paclitaxel magnitude by the two fungal strains, several fermentation conditions including selection of the proper fermentation medium, agitation rate, incubation temperature, fermentation period, medium pH, medium volume, and inoculum nature (size and age of inoculum) were tried. Fermentation process carried out in M1D medium (pH 6.0) and maintained at 120 rpm for 10 days and at 25 °C using 4% (v/v) inoculum of 5-day-old culture stimulated the highest paclitaxel production to attain 307.03 µg L-1 by the A. fumigatus strain. In the case of the A. tenuissima strain, fermentation conditions conducted in flask basal medium (pH 6.0) and maintained at 120 rpm for 14 days and at 25 °C using 8% (v/v) inoculum of 7-day-old culture were found the most favorable to attain the highest paclitaxel production of 124.32 µg L-1. Using the MTT-based assay, fungal paclitaxel significantly inhibited the proliferation of five different cancer cell lines with 50% inhibitory concentration values varied from 3.04 to 14.8 µg mL-1. Hence, these findings offer new and alternate sources with excellent biotechnological potential for paclitaxel production by fungal fermentation.

Isolation of cryptococcus, Candida, Aspergillus, Rhodotorula and nocardia from meningitis patients in egypt.

Meningitis occurs throughout Egypt and is largely attributed to bacterial pathogens, but there is little information on fungal etiologies of meningitis. We, therefore, investigated fungal infections among Egyptian patients with acute and subacute meningitis who tested negative for bacterial and viral agents. A total of 1000 cerebrospinal fluid (CSF) samples collected from nine governorates of Egypt during 1998-2002 were initially stained with Gram's, India ink, and lacto-phenol cotton-blue stains, and examined under light microscope to detect fungal elements. All CSF samples were cultured on brain heart infusion, Wickerham and Staib agar media for fungus isolation. CSF with suspected Cryptococcus neoformans infections were also tested by latex agglutination test for antigen detection. Species identification of selected isolates was carried out at the Mycotic Diseases Branch, CDC, Atlanta, Georgia, USA. Fungal agents were detected microscopically and by culture in 17 of 1000 (1.7%) CSF samples tested. Ten of 17 were identified as C. neoformans var grubii (serotype A), 4 as Candida albicans, and one each of Aspergillus candidus, Rhodotorula mucilaginosa (rubra) and Nocardia spp (actinomycetes). Out of the 17 cases with fungal CSF infection, 8 died (Cryptococcus-3, Candida-2, Aspergillus, Rhodotorula and Nocardia) and 2 suffered neurological sequelae. Of the 10 cryptococcal meningitis patients, 4 were HIV positive and one was diagnosed with lymphoma. To our knowledge, this is the first study on isolation of fungi other than Cryptococcus from CSF of Egyptian patients with acute/subacute meningitis. Consideration must now be given to cryptococcosis and candidiasis as potential etiologies of meningitis in Egypt.