Recovery of chitin and chitosan from shrimp waste with microwave technique and versatile application / Recuperação de quitina e quitosana de resíduos de camarão por micro-ondas e aplicação versátil

In this study, chitin and chitosan were extracted from Litopenaeus vannamei waste using chemical and microwave methods. Shrimp waste was cleaned, dried and ground sieved to 16, 32 and 60 mesh, and the samples were depigmented, demineralized, and deproteinized. Then, the chitin was submitted to a deacetylation process by 45% NaOH solution under microwave irradiation at 600w, for intermittent 15 min or using 5 pulses of 5 minutes. The study showed that the effectiveness of the particle size of 32 mesh and 6 pulses of 5 min to deacetylation with 92% of degree and chitosan yield (52.2%). The polymer chitosan showed higher antimicrobial activity against to Staphylococcus aureus, Escherichia coli, Salmonella enterica and the yeast Candida sp., respectively. The results indicated the feasibility of the microwave radiation as an attractive method to recover chitin and chitosan from shrimp wastes.(AU)

Neste estudo, a quitina e a quitosana foram extraídas de resíduos de Litopenaeus vannamei utilizando métodos químicos e do micro-ondas. Os resíduos de camarão foram limpos, secos e peneirados a 16, 32 e 60 mesh, e as amostras foram despigmentadas, desmineralizadas e desproteinizadas. Posteriormente, a quitina foi submetida a processo de desacetilação por solução de NaOH a 45% sob irradiação de micro-ondas a 600w, durante 15 min intermitentes ou utilizando 6 pulsos de 5 min. O estudo mostrou eficácia nas partículas com tamanho de 32 mesh e 6 pulsos de 5 minutos, com 92% grau de desacetilação e rendimento de quitosana (52,2%). A atividade antimicrobiana foi para Staphylococcus aureus, Escherichia coli e Salmonella enterica contra a levedura Candida sp., respectivamente. Os resultados indicaram a viabilidade da radiação de micro-ondas como um método atraente para recuperação de quitina e quitosana a partir de resíduos de camarão.(AU)

Método, escrita e narrativa: histórias de um grupo que chegou à velhice / Narrative, writing and method: about an old age group

O artigo apresenta uma reflexão sobre escrita e pesquisa a partir do relato de uma experiência em oficinas terapêuticas para pessoas que chegaram à velhice. Amparando-se nas ideias de autores como Márcia Moraes, Bruno Latour e Jeanne Marie Gagnebin, que produzem conhecimento acompanhando os percursos singulares e ouvindo os sujeitos no que eles têm a dizer, o texto foi desenvolvido numa escrita narrativa, trazendo a proximidade dos encontros, suas descobertas e hesitações, no próprio relato da experiência e discussão dos conceitos.

The article presents a point-of-view on both writing and research. It was conceived in therapeutic workshops with elderly people. The text was written in a narrative format and it was inspired by Marcia Moraes, Bruno Latour and Jeanne Marie Gagnebin. Such authors have developed their body of knowledge by observing other people's paths and by listening to them as well. The article addresses the workshop meetings, the group discoveries and questions, individual stories and conceptual discussions.

El artículo presenta uma reflexión acerca de la metodologia y escritura del trabajo de investigación, a partir de una experiencia en espacios terapêuticos para personas que han llegado a edade avanzada . El texto trae ideas de autores como Márcia Moraes, Bruno Latour e Jeanne Marie Gagnebin, que producem conocimento escuchando el campo, y usa el estilo de la narrativa como principal conductor, incluyendo en su redación lo que se ha pasado en los encuentos en campo.

Heavy metal biosorption by chitin and chitosan isolated from Cunninghamella elegans (IFM 46109)

Chitin and chitosan were extracted from mycelial biomass of Cunninghamella elegans and the performance for copper, lead and iron biosorption in aqueous solution was evaluated. The growth curve of C. elegans was accomplished by determination of biomass, pH, glucose and nitrogen consumption. Chitin and chitosan were extracted by alkali-acid treatment and the yields were 23.8 and 7.8 percent, respectively. For the adsorption analysis, the process of heavy uptake metal sorption was evaluated using polysaccharides solutions (1 percent w/v). The rate of metallic biosorption was dependent upon the concentration and pH of metal solutions, and the best results were observed with pH 4.0. Chitosan showed the highest affinity for copper and chitin for iron adsorption. The results suggest that C. elegans (IFM 46109) is an attractive source of production of chitin and chitosan, with a great potential of heavy metals bioremediation in polluted environments.