Desilked silkworm (Bombyx mori L.) pupae oil has been identified as a valuable source of unsaturated fatty acids (UFAs). However, direct consumption is a food safety issue due to the presence of sn-1,3 triacylglycerols (TAGs), including palmitic acid (PA). A simple, selective and safe conversion to structured triacylglycerols (STAGs) with high UFA content is highly desirable. Novel STAGs with low PA and high a-linolenic acid (ALA), oleic acid (OA) and linoleic acid (LA) content were synthesized from silkworm pupae oil using a solvent-free system catalyzed by Lipozyme RM IM. Crystallization and melting profiles were determined using thermograms, and optimal conditions involved an enzyme load of 7%, a silkworm pupae oil TAG to OA molar ratio of 1:5, and a reaction temperature of 60°C. The content of PA and stearic acid decreased from 41.04 to 20.11%, while UFAs increased from 61.12 to 77.88%. The STAGs exhibited lower crystallization (À15.44°C) and melting (À23.47°C) profiles than TAGs (4.64 and À5.58°C, respectively).Practical applications: The presented methods using a solvent-free system enable STAGs to be synthesized using a natural substrate (desilked silkworm pupae oil). A simple, selective and safe conversion to STAGs with high UFA content and low PA content is highly desirable. This STAG is rare in nature and chemical synthesis is cumbersome. This STAG could be applied as a clinical treatment for nutritional enhancement with a beneficial effect on human health because of the high content of the ALA.
The application of whole cells as catalytic biofilms in microchannels has attracted increasing scientific interest. However, the excessive biomass formation and structure of biofilms in a reactor limits their use. A microchannel reactor with surface modification was used to colonize recombinant Escherichia coil BL21-pET28a-egfp rapidly and accelerated growth of biofilms in the microchannel. The segmented flow system of ‘air/culture medium containing nanomaterials’ was firstly used to modulate the biofilms formation of recombinant E. coil; the inhibitory effects of nanomaterials on biofilm formation were investigated. The results indicated that the segmental flow mode has a significant impact on the structure and development of biofilms. Using the channels modified by silane reagent, the culture time of biofilms (30 h) was reduced by 6 h compared to unmodified channels. With the addition of graphene sheets (10 mg/L) in Luria-Bertani (LB) medium, the graphene sheets possessed a minimum inhibition rate of 3.23% against recombinant E. coil. The biofilms cultivated by the LB medium with added graphene sheets were stably formed in 20 h; the formation time was 33.33% shorter than that by LB medium without graphene. The developed method provides an efficient and simple approach for rapid preparation of catalytic biofilms in microchannel reactors.
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