RESUMO
Two lactic bacteria were used in sequential co-cultures to demineralize (DM) and deproteinize (DP) shrimp shells (SS) to obtain chitin. During the first 24 h, Lactobacillus delbrueckii performed the DM in a minimal medium containing 100 g/L SS and 50 g/L glucose. Then, three different conditions were assayed to complete DM and perform the DP stage: 1) Bifidobacterium lactis was added with 35 g/L of glucose (Ld-G â Bl-G); 2) only B. lactis was added (Ld-G â Bl); and 3) a 35 g/L pulse of glucose was added, and at 48 h, B. lactis was inoculated (Ld-G â G â Bl). The highest DM (98.63 %) and DP (88 %) were obtained using a glucose pulse in the DM step and controlling the pH value above 6.0 in the DP step. Finally, a deacetylases cocktail produced by Aspergillus niger catalyzed the deacetylation of the resulting chitin. The chitosan samples had a deacetylation degree higher than 78 % and a solubility of 25 % in 1.0 N acetic acid. The deacetylation yield was 74 % after a mild chemical treatment, with a molecular weight of 71.31 KDa. This work reports an entirely biological process to get chitin and chitosan from SS with high yields.
Assuntos
Quitosana , Animais , Quitosana/química , Quitina/química , Crustáceos , Biotecnologia , GlucoseRESUMO
An integral bioprocess to produce lactic acid (LA) from banana peel (BP) was studied. Oxidases produced by Trametes versicolor and hydrolases produced by Aspergillus flavipes and Aspergillus niger saccharified BP at optimal conditions: 230 rpm, 66 g/L BP, and 73.5% (v/v) of enzymatic crude extract (using equal quantities of the enzymatic extracts). At bioreactor scale (1 L), the joint action of oxidases and hydrolases released 18 g/L of reducing sugars (RS) after 24 h (60% corresponded to glucose), consuming the BP polysaccharides. Lactobacillus delbrueckii fermented the released RS, producing 10 g/L of LA; while in the sequential fermentation (inoculating L. delbrueckii after saccharification), 28 g/L of LA were produced, observing an apparent decrease in feedback inhibition of hydrolases below 1.5 g/L of RS. This process is susceptible for upscaling to produce high LA concentrations and represents a platform to utilize agroindustrial wastes to obtain value-added products.
Assuntos
Metabolismo dos Carboidratos , Fermentação , Ácido Láctico/biossíntese , Musa/metabolismo , Aspergillus/metabolismo , Trametes/metabolismoRESUMO
En la Leucemia linfática aguda (LLA) pediátrica las cinco fusiones génicas más frecuentes descritas son: ETV6/RUNX1, BCR/ABL variante p190, BCR/ABL variante p210, E2A/PBX1, MLL/AF4 y representan alrededor del 40%. Se busca determinar la frecuencia e importancia de las principales fusiones génica en la leucemia linfática en un grupo de pacientes pediátricos del INEN. Se realizó el análisis molecular de cinco genes de fusión en 23 pacientes con diagnóstico de LLA-B, obteniéndose las siguientes frecuencias: ETV6/RUNX1 (17.4%), BCR/ABL variante p190 (8.7%), BCR/ABL variante p210 (8.7%), E2A/PBX1 (8.7%), MLL/AF4 (4.3%). Esta metodología de estudio de los cinco genes de fusión, debe considerarse como herramienta de apoyo al diagnóstico y monitoreo en uso de terapias blanco en todos los casos de la LLA-B pediátricas.