Fungal decomposition of chicken-feather waste in submerged and solid-state fermentation / Decomposição fúngica de resíduos de pena de frango em fermentação submersa e de estado sólido

Abstract Poultry industry is expanding rapidly and producing million tons of feather waste annually. Massive production of keratinaceous byproducts in the form of industrial wastes throughout the world necessitates its justified utilization. Chemical treatment of keratin waste is proclaimed as an eco-destructive approach by various researchers since it generates secondary pollutants. Keratinase released by a variety of microbes (bacteria and fungi) can be used for the effective treatment of keratin waste. Microbial degradation of keratin waste is an emerging and eco-friendly approach and offers dual benefits, i.e., treatment of recalcitrant pollutant (keratin) and procurement of a commercially important enzyme (keratinase). This study involves the isolation, characterization, and potential utility of fungal species for the degradation of chicken-feather waste through submerged and solid-state fermentation. The isolated fungus was identified and characterized as Aspergillus (A.) flavus. In a trial of 30 days, it was appeared that 74 and 8% feather weight was reduced through sub-merged and solid-state fermentation, respectively by A. flavus. The pH of the growth media in submerged fermentation was changed from 4.8 to 8.35. The exploited application of keratinolytic microbes is, therefore, recommended for the treatment of keratinaceous wastes to achieve dual benefits of remediation.

Resumo A indústria avícola está se expandindo rapidamente e produzindo milhões de toneladas de resíduos de penas anualmente. A produção massiva de subprodutos queratinosos na forma de resíduos agrícolas e industriais em todo o mundo exige sua utilização justificada. O tratamento químico de resíduos de queratina é proclamado como uma abordagem ecodestrutiva por vários pesquisadores, uma vez que gera poluentes secundários. A queratinase liberada por uma variedade de micróbios (bactérias e fungos) pode ser usada para o tratamento eficaz de resíduos de queratina. A degradação microbiana de resíduos de queratina é uma abordagem emergente e ecológica e oferece benefícios duplos, ou seja, tratamento de poluente recalcitrante (queratina) e obtenção de uma enzima comercialmente importante (queratinase). Este estudo envolve o isolamento, caracterização e utilidade potencial de espécies de fungos para a degradação de resíduos de penas de frango por meio da fermentação submersa e em estado sólido. O fungo isolado foi identificado e caracterizado como Aspergillus (A.) flavus. Em um ensaio de 30 dias, constatou-se que 74% e 8% do peso das penas foram reduzidos por A. flavus, respectivamente, por meio da fermentação submersa e em estado sólido. O pH do meio de crescimento em fermentação submersa foi alterado de 4,8 para 8,35. A aplicação explorada de micróbios queratinolíticos é, portanto, recomendada para o tratamento de resíduos ceratinosos para obter benefícios duplos de remediação.

Keratinolytic abilities of Micrococcus luteus from poultry waste

Keratinolytic microorganisms have become the subject of scientific interest due to their ability to biosynthesize specific keratinases and their prospective application in keratinic waste management. Among several bacterial classes, actinobacteria remain one of the most important sources of keratin-degrading strains, however members of the Micrococcaceae family are rarely scrutinized in regard to their applicatory keratinolytic potential. The tested Micrococcus sp. B1pz isolate from poultry feather waste was identified as M. luteus. The strain, grown in the medium with 1–2% chicken feathers and a yeast extract supplement, produced keratinases of 32 KU and lower level of proteases, 6 PU. It was capable to effectively decompose feathers or “soft” keratin of stratum corneum, in contrast to other “hard” hair-type keratins. The produced keratinolytic enzymes were mainly a combination of alkaline serine or thiol proteases, active at the optimum pH 9.4, 55 °C. Four main protease fractions of 62, 185, 139 and 229 kDa were identified in the crude culture fluid. The research on the auxiliary role of reducing factors revealed that reducing sulfur compounds could be applied in keratinolysis enhancement during enzymatic digestion of keratin, rather than in culture conditions. The presented M. luteus isolate exhibits a significant keratinolytic potential, which determines its feasible applicatory capacity towards biodegradation of poultry by-products or formulation of keratin-based feed components..(AU)

Dermatophytes and other associated fungi in patients attending to some hospitals in Egypt

Dermatophytes are keratinophilic fungi that infect keratinized tissues causing diseases known as dermatophytoses. Dermatophytes are classified in three genera, Epidermophyton, Microsporum, and Trichophyton. This investigation was performed to study the prevalence of dermatomycosis among 640 patients being evaluated at the dermatology clinics at Kasr elainy, El-Husein and Said Galal hospitals in Cairo and Giza between January 2005 and December 2006. The patients were checked for various diseases. Tinea capitis was the most common clinical disease followed by tinea pedis and tinea corporis. Tinea cruris and tinea unguium were the least in occurrence. Tinea versicolor also was detected. The most susceptible persons were children below 10 years followed by those aged 31–40 years. Unicellular yeast was the most common etiological agent and T. tonsuranswas the second most frequent causative agent followed by M. canis..(AU)