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In this study, the effect of the addition of hyaluronic acid (HA) on bacterial cellulose (BC) production, under static conditions was evaluated in terms of the properties of the resulting BC hybrid membranes. HA was added to the fermentation process in three distinct time points: first day (BC-T0), third day (BC-T3) and sixth day (BC-T6). Analyses of FT-IR and CP/MAS (13)C NMR confirmed the presence of HA in bacterial cellulose membranes. The crystal structure, crystallinity index (Ic) surface roughness, thermal stability and hybrophobic/hydrophilic character changed. Membranes with higher roughness were produced with HA added on the first and third day of fermentation process. The surface energy of BC/HA membranes was calculated and more hydrophilic membranes were produced by the addition of HA on the third and sixth day, also resulting in more thermally stable materials. The results demonstrate that bacterial cellulose/hyaluronic acid hybrid membranes can be produced in situ and suggest that HA interacts with the sub-elementary bacterial cellulose fibrils, changing the properties of the membranes. The study and understanding of the factors that affect those properties are of utmost importance for the safe and efficient use of BC as biomaterials in numerous applications, specifically in the biological field.

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Research background. Despite the great properties of bacterial cellulose, its manufacture is still limited due to difficulties in production at large-scale. These problems are mainly related to low production yields and high overall costs of the conventional culture media normally used. Reversing these problems makes it necessary to identify new cheap and sustainable carbon sources. Thus, this work aimed to isolate and select a high cellulose-producing Komagataeibacter strain from vinegar industry, and study their potential for bacterial cellulose synthesis in an industrial soybean co-product, known as soybean molasses, to be used as fermentation medium. Experimental approach. For one isolated strain that exhibited high level of cellulose production in the standard Hestrin-Schramm medium, the ability of this biopolymer production in a soybean molasses-based medium was determined. The produced membranes were characterized by thermogravimetric analysis, X-ray diffraction, infrared spectroscopy, water holding capacity and rehydration ratio for determination of its characteristics and properties. The selected strain was also characterized by genetic analysis for determination of its genus and specie. Results and conclusions. An isolated strain was genetically identified as Komagataeibacter intermedius V-05 and exhibited the highest cellulose production in Hestrin-Schramm medium (3.7 g/L). In addition, the production by this strain in soybean molasses-based medium was 10.0 g/L. Membranes from both substrates were similar in terms of chemical structure, crystallinity and thermal degradation. Soybean molasses proved to be a suitable alternative medium for biosynthesis of cellulose in comparison with standard medium. In addition to providing higher production yield, the membranes showed great structural characteristics, similar to those obtained from standard medium. Novelty and scientific contribution. In this research, we have isolated and identified a Komagataeibacter strain which exhibits a high capacity for cellulose production in soybean molasses medium. The isolation and selection of strains with high capacity of microbial metabolites production is important for decreasing bioprocess costs. Furthermore, as there is a necessity today to find cheaper carbon sources that provide microbial products at a lower cost, soybean molasses represents an interesting alternative medium to produce bacterial cellulose prior to its industrial application.

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Caixa postal 6001 -CEP 86051-990, Londrina -Paraná -cesar.tischer@uel.br RESUMOMembranas de celulose são formas farmacêuticas com aplicação médica promovendo a regeneração tecidual. A membrana de celulose bacteriana de estrutura cristalina apresenta características físico-químicas únicas, como resistência mecânica, térmica, porosidade e molhabilidade. O objetivo deste trabalho foi preparar membranas para funcionalização com princípios ativos com papel no processo de regeneração tecidual. Para tanto, adicionamos à membrana produzida por Gluconacetobacter xylinus grupos cloroacetil a partir de reação com Cloroacetato de sódio, variando tempos de reação em refluxo. Os resultados foram monitorados por espectroscopia de Infra-Vermelho (FT-IR), ressonância magnética nuclear no estado sólido (CP-MAS NMR), bem como por termogravimetria (TG). Foi observado que foram necessárias 4 horas de reação para que a membrana apresentasse sinais no FT-IR consistentes com o produto cloroacetilado; o espectro de cp-mas nmr deste tempo comprovou a presença de grupo cloroacetil covalentemente ligado. A análise calorimétrica apresenta perfil de perda de massa que concorda com a perda de um grupo ligado antes da desestruturação total da cadeia celulósica. Conclui-se que foi adicionado o grupo cloroacetil, e a este poder-se-á adicionar outros grupos funcionais de princípios ativos funcionalizando a membrana de celulose bacteriana.Palavras-chave: celulose, Gluconacetobacter xylinus, cloroacetilação, termogravimetria, ressonância mafnética nuclear do estado sólido. INTRODUÇÃOA celulose produzida pela bactéria Acetobacter xylinum (renomeada para Gluconacetobacter xylinus) possui propriedades peculiares que a diferem consideravelmente da celulose de planta. A celulose bacteriana é obtida pura, ou seja, livre de lignina e hemiceluloses, extremamente hidrofílica e possui cristalinidade superior a da maioria das outras fontes deste biopolímero. Essas propriedades aliadas a estrutura tridimensional nanométrica conferem uma amplo leque de áreas de aplicação que tem como principal o uso na área médica, além da indústria alimentícia e eletrônica. Na área médica destaca-se a aplicação como substituto temporário da pele no tratamento de queimados e feridas de difícil cicatrização 1 .