The gene for a Geobacillus thermoleovorans CCR11 thermostable lipase was recovered by PCR and cloned. Four genetic constructions were designed and successfully expressed in E. coli: (i) the lipase structural gene (lipCCR11) in the PinPoint Xa vector; (ii) the lipase structural gene (lipACCR11) in the pET-28a(+) vector; (iii) the lipase structural gene minus the signal peptide (lipMatCCR11) in the pET-3b vector; and (iv) the lipase structural gene plus its own promoter (lipProCCR11) in the pGEM-T cloning vector. The lipase gene sequence analysis showed an open reading frame of 1,212 nucleotides coding for a mature lipase of 382 residues (40 kDa) plus a 22 residues signal peptide. Expression under T7 and T7lac promoter resulted in a 40- and 36-fold increase in lipolytic activity with respect to the original strain lipase. All recombinant lipases showed an optimal activity at pH 9.0, but variations were found in the temperature for maximum activity and the substrate specificity among them and when compared with the parental strain lipase, especially in the recombinant lipases that contained fusion tags. Therefore, it is important to find the appropriate expression system able to attain a high concentration of the recombinant lipase without compromising the proper folding of the protein.

Differences in sensitivity to 6-n-propylthiouracil (PROP) are associated with TAS2R38 genotypes. Those differences allow the classification in "nontasters" (NT), "tasters" (MT) and "supertasters" (ST), which have been related to differences in taste acuity and nutritional status, although there is controversy in the results obtained by different research groups. The aim of this study was to determine the frequencies of NT, MT and ST, TAS2R38 genotypes and to analyze its relationship with taste sensitivity, food consumption and anthropometric measures in healthy Mexican adults. Body Mass Index (BMI), Waist Circumference (WC), TAS2R38 genotype, detection thresholds for sucrose, capsaicin, PROP and linoleic acid as well as intensity perceived for sucrose, capsaicin and PROP suprathreshold solutions were performed in 76 Mexican adults. Food restriction was assessed and two sevenday food consumption records from 66 individuals were analyzed. The proportion of subjects with genotype AVI/AVI, and its associated phenotype NT, was close to 10%; the proportion of MT and ST was 54.6 and 31.8 respectively. Genotypes associated with ST were present in 38%, while those associated with MT accounted for 41% of the population. PROP sensitivity was associated with linoleic acid sensitivity, consumption of vegetables, grains and dairy foods. BMI and WC were negatively correlated to carbohydrate intake and linoleic acid detection threshold. PROP taster status and TAS2R38 genotypes were related. PROP and linoleic acid sensitivity influences food consumption in unrestrained eaters and could produce differences in long-term nutritional status.

The recombinant lipase LipMatCCR11 from the thermophilic strain Geobacillus thermoleovorans CCR11 was applied in the synthesis of n-butyl caproate via transesterification in hexane and xylene. The short chain flavour ester was obtained by alcoholysis from ethyl caproate and n-butyl alcohol and acidolysis from n-butyl butyrate and caproic acid. This enzyme was also used in the condensation reaction from caproic acid and n-butanol. The conversion percentages at equilibrium (Xe) were similar to those obtained with Candida antarctica lipase fraction B (CAL-B) in the same reaction conditions, while lower conversion velocities (k) were attained. LipMatCCR11 reached high conversion percentages in either hexane or xylene as organic media (> 63%); the enzyme was also able to catalyze the aminolysis reaction of ethyl caproate with benzyl amine in hexane obtaining a conversion percentage > 62%.

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