No abstract

In this work, a novel nanobiocatalyst (L–Mcn4@Ca2Fe2O5) was synthesized from Bacillus lipase on srebrodolskite nanoparticles. Bacillus sp. MCn4 culture media was optimized reaching the maximum lipolytic activity using peptone 7.5 g/L and sucrose 5 g/L and Ca2Fe2O5, was synthesized and characterized (size of 100–150 nm). L–Mcn4@Ca2Fe2O5 was obtained by adsorption (12 U/mg oxide) and successfully characterized by different techniques. According to the best immobilization conditions, pH 4 and 100 Mm ionic strength, an adsorption model with two stages was proposed: initial interfacial activation followed by multi‐point electrostatic interactions. Stability studies showed an enhancement in its performance between 50 and 70 °C and against ethanol compared with free enzyme and the thermal decomposition process was softer when lipase was immobilized. The biocatalyst hydrolyzed fish oil showing enrichment in the PUFAs content with an increase on DHA of 1.2 fold showing a great potential for its use in the food industry.

Prevotella copri is a bacterium that can be found in the human gastrointestinal tract. The role of P. copri in the GIT is unclear, and elevated numbers of the microbe have been reported both in dietary fiber-induced improvement in glucose metabolism but also in conjunction with certain inflammatory conditions. These findings raised our interest in investigating the possibility of P. copri to grow on xylan, and identify the enzyme systems playing a role in digestion of xylan-based dietary fibers. Two xylan degrading polysaccharide utilizing loci (PUL10 and 15) were found in the genome, with three and eight glycoside hydrolase (GH) -encoding genes, respectively. Three of them were successfully produced in Escherichia coli: One extracellular enzyme from GH43 (subfamily 12, in PUL10, 60 kDa) and two enzymes from PUL15, one extracellular GH10 (41 kDa), and one intracellular GH43 (subfamily 137 kDa). Based on our results we propose that in PUL15, GH10 (1) is an extracellular endo-1,4-β-xylanase, that hydrolyses mainly glucuronosylated xylan polymers to xylooligosaccharides (XOS); while, GH43_1 in the same PUL, is an intracellular β-xylosidase, catalysing complete hydrolysis of the XOS to xylose. In PUL10, the characterized GH43_12 is an arabinofuranosidase, with a role in degradation of arabinoxylan, catalysing removal of arabinose-residues on xylan.