Obtaining hemicellulosic hydrolysate from sugarcane bagasse for microbial oil production by Lipomyces starkeyi.

OBJECTIVE: The extraction of the hemicellulose fraction of sugarcane bagasse (SCB) by acid hydrolysis was evaluated in an autoclave and a Parr reactor aiming the application of the hydrolysate as a carbon source for lipid production by Lipomyces starkeyi. RESULTS: The hydrolysis that resulted in the highest sugar concentration was obtained by treatment in the Parr reactor (HHR) at 1.5% (m/v) H2SO4 and 120 °C for 20 min, reaching a hemicellulose conversion of approximately 82%. The adaptation of the yeast to the hydrolysate provided good fermentability and no lag phase. The fermentation of hemicellulose-derived sugars (HHR) by L. starkeyi resulted in a 27.8% (w/w) lipid content and YP/S of 0.16 g/l.h. Increasing the inoculum size increased the lipid content by approximately 61%, reaching 44.8% (w/w). CONCLUSION: The hemicellulose hydrolysate from SCB is a potential substrate for L. starkeyi to produce lipids for biodiesel synthesis based on the biorefinery concept.

Caffeine degradation by Rhizopus delemar in packed bed column bioreactor using coffee husk as substrate

Various microorganisms including bacteria, yeast and fungi can degrade caffeine. There are few publications about caffeine degradation pathway in filamentous fungi, mainly by solid-state fermentation (SSF). Studies were carried out on degradation of caffeine and their metabolites by filamentous fungi in SSF using coffee husk as substrate. The purpose of this work was to investigate the caffeine degradation pathway by Rhizopus delemar in packed bed column fermenter and to compare this degradation metabolism with glass flasks fermentation. The methylxanthines were quantified by HPLC analysis. The experiments were realized with the optimized conditions in previous experiments: pH 6.5, 28ºC, inoculation rate 10(6) spores/g substrate, aeration rate 60 mL/min and initial moisture 73%. Under these conditions, after 72 hous of fermentation was achieved only 0.19% of caffeine and 0.014% of theophylline in the coffee husk. The strain proved to be able for caffeine and theophylline degradation by SSF in packed bed column bioreactor.

Diversos microrganismos incluindo bactérias, fungos e leveduras são capazes de assimilar a cafeína de meios sintéticos ou de resíduos de café. Existem poucos trabalhos sobre a via de degradação da cafeína em fungos filamentosos, principalmente por fermentação no estado sólido (FES). Estudos de degradação da cafeína por fungos filamentosos em FES usando casca de café como substrato vêm sendo realizados. O objetivo deste trabalho foi investigar a via de degradação da cafeína por Rhizopus delemar em biorreator de colunas aeradas e comparar este metabolismo de degradação com o da fermentação em frascos de vidro. As metilxantinas foram quantificadas por análises em HPLC. Os experimentos foram realizados com as condições otimizadas previamente: pH 6,5, 28ºC, 10(6) espores/g substrato, vazão de ar 60 mL/min e 73% de umidade inicial. Após 90 horas de fermentação, 65% da cafeína foi reduzida, resultando 0,19% de cafeína e 0,014% de teofilina na casca de café. Esta cepa provou ter habilidade para degradar cafeína e teofilina por FES em biorreator de colunas.

Preparative chromatography of xylanase using expanded bed adsorption.

Expanded bed adsorption was used to purify a marketable xylanase often used in the kraft pulp bleaching process. Experiments in packed and expanded beds were carried out mainly to study the adsorption of xylanase on to a cationic adsorbent (Streamline SP) in the presence of cells. In order to study the presence of cells, a Bacillus pumilus mass (5% wet mass) was mixed with the enzyme extract and submitted to an expanded bed adsorption system. One xylanase was purified to homogeneity in the packed bed. However, the 5% cell content hampered purification.