No abstract

No abstract

Two extracellular keratinases of Scopulariopsis brevicaulis were purified and partially characterized. The enzymes were isolated by the techniques of gel filtration chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). These keratinases (K I & K II) were purified approximately 33 and 29 fold, respectively. SDS-PAGE of the products of gel filtration chromatography (K I & II) produced only one band each, suggesting homogeneity. The optimum pH for both keratinases was 7.8, while the optimum temperatures were 40 degrees C (K I) and 35 degrees C (K II). Estimated molecular weights were 40-45 KDa and 24-29 KDa for K I & K II respectively. Both keratinases were inhibited by phenylmethylsulfonyl fluoride which suggests a serine residue at or near an active site.

No abstract

Keratinolytic microbes represent an important component of soil biocenosis where they mineralize a highly resistant proteinaceous substrate "keratin" of vertebrate skin and its adnexes. Most research on the biodegradation of keratin has been carried out with dermatophytic (Deshmukh and Agrawal, 1985;Evans and Hose, 1975;Kunert, 1989) and nondermatophytic (Rajak et al., 1991(Rajak et al., , 1992 fungi and actinomycetes (Kunert, 1989;Noval and Nickerson, 1959), and the work with bacterial species has been little. The results obtained by Noval and Nickerson (1959) and Kunert (1989) with Streptomyces fradiae revealed that the degradation of hard keratins is due not only to extracellular protease (keratinase); it is always accompanied by the denaturation of keratin substrate by direct reduction, proteolysis, and finally by the marked alkalinization of the medium. The biochemical mechanism of keratin degradation by bacteria also centers on three interlinked processes: denaturation of the substrate, proteolysis, and deamination. The more important bacteria involved in the degradation of wool and other animal fibers include Bacillus putrificus, B. subtilis, B. cereus, and B. mesentericus.In the present paper, an in vitro degradation of keratin substrates by a strain of B. subtilis and two strains of Bacillus licheniformis has been studied. Materials and MethodsMicroorganisms. B. subtilis S1 (MTCC 2616) and B. licheniformis S21 (MTCC 2617) and S23 (MTCC 2618) were recovered from the soils of gelatin factory campus, Jabalpur, and were maintained on glucosepeptone-agar slants at 28Ϯ1°C.Substrate sterilization. Child's scalp hair, cow horn, cow hooves, and human nails were sterilized by the procedure described by Evans and Hose (1975). Inoculum. A loopful from 10-day-old culture of test organism was added to sterilized distilled water, and 1 ml of this inoculum was aseptically transferred to sterile basal salt medium divided into three sets.( i ) Keratin control: 200 mg of keratin substrate ϩ50 ml of medium. (ii) Bacterial control: 1 ml of inoculumϩ50 ml of medium. (iii) Test samples: 200 mg of keratin substrate ϩ50 ml of mediumϩ1 ml of inoculum. All flasks were incubated under stationary conditions at 28Ϯ1°C for 28 days in triplicates.Analysis. Aliquots were removed at the end of each incubation period through preweighed Whatman filter paper No. 42. The culture filtrate was centrifuged at 3,000 rpm for 5 min, and the supernatant was subjected to various biochemical tests.( i ) Determination of pH: Changes in the alkalinity of the culture filtrate was recorded weekly (7, 14, 21, 28 days) (Received May 17, 1999; Accepted November 12, 1999) The ability of two species of Bacillus to degrade child's scalp hair, cow horn, cow hooves, and human nails in vitro under static conditions was studied by the determination of soluble sulphhydryl compounds as cysteine, disulphides as cystine, and release of extracellular keratinase along with changes in alkalinity of the culture filtrate. Child's scalp hair was found to be the most ...