Screening and Molecular Identification of New Microbial Strains for Production of Enzymes of Biotechnological Interest

ABSTRACT: This research focused on isolation, identification and characterization of new strains of fungi and bacteria, which were able to produce extracellular xylanase, mannanase, pectinase and α-amylase. Fungi isolates were identified on the basis of analyses of 18S gene sequencing and internal transcribed spacer region. The closest phylogenetic neighbors according to 18S gene sequence and ITS region data for the two isolates M1 and SE were Aspergillus fumigatus and Aspergillus sydowii, respectively. I4 was identified as Bacillus mojavensis on the basis of the 16S rRNA gene sequencing and biochemical properties. The enzyme production was evaluated by cultivating the isolated microorganisms in liquid-state bioprocess using wheat bran as carbon source. Two fungi (M1, and SE) and one bacterium (I4) strains were found to be xylanase producer, and several were proven to be outstanding producers of microbial xylanase. The strains producing xylanase secreted variable amounts of starch-debranching enzymes and produced low level β-mannan-degrading enzyme systems. The bacterium strain was found to be capable of producing pectinolytic enzymes on wheat bran at high level. Some of the strains have good potential for use as sources of important industrial enzymes.

A Case of Toenail Onychomycosis Due to Aspergillus sydowii Infection / 대한의진균학회지

Onychomycosis is caused by dermatophytes usually, but some species of nondermatophytic molds and yeasts are also associated with invasion of nails. Aspergillus sydowii is a nondermatophytic mold which is opportunistic filamentous fungus in all environments. We report a case of onychomycosis caused by A. sydowii in a 65-year-old male. The patient showed yellowish discoloration with hyperkeratotic change on the distal and lateral portion of both great toenails. Direct microscopic examination of scraping on the potassium hydroxide preparation revealed dichotomous septate hyphae and repeated cultures on Sabouraud dextrose agar showed the same blue green velvety colonies. Biseriate phialides that cover entire vesicle with conidial structure resembling Penicillium were shown in the slide culture. The DNA sequence of internal transcribed spacer (ITS) region of clinical sample was 99% match to that of A. sydowii strain XWSFJJ1 (GenBank accession number FJ461692). We confirmed A. sydowii by KOH mount, colony, light microscopic morphology and DNA sequence analysis. The patient was treated with 250 mg oral terbinafine daily and topical 5% amorolfine nail lacquer for 3 months.

Enhanced production of pectinolytic enzymes from immobilized cells of mixed aspergillus species.

The cells of isolated mixed culture of Aspergillus fumigatus and Aspergillus sydowii were immobilized in calcium alginate beads. Studies were carried out on different parameters like alginate concentration, incubation time and bead inoculum which affects the productivity and stability of the immobilized system. The best enzymatic activities were obtained with 3% alginate concentration, 48h of incubation time and 200 beads/flask of inoculum. Optimization of these factors causes an increase in enzymatic activities and the possibility of semicontinuous cultivation. Immobilized cells could be reused in five successive reaction cycles with a slight decrease in activities.

A Simple Detection Method of the Resistance to the Treatment of Onychomycosis: A Case Report of Aspergillus sydowii Onychomycosis

A 35-year-old housewife was diagnosed with onychomycosis and treated by oral terbinafine, 250mg/day, for 4 months. Clinically all infected nails improved gradually. However, her left great toe-nail was not improved thereafter. At that time the proximal end of the onychomycotic lesion was marked with surgical blade, and terbinafine therapy was continued for four weeks. However, the onychomycotic nail was not improved, and the scratch mark passed by the proximal end of the infected nail. Therefore, we detected the resistance to the therapy and switched the medication to itraconazole 100 mg/day and then another scratch mark was done at the proximal end of the onychomycotic lesion. After another 2 weeks the infected nail went along with the scratch mark distally, and showed clinical improvement. After 8 weeks therapy of itraconazole, she was cured clinically and mycologically. The fungal culture was identified as Aspergillus sydowii.