The effects of structural modification of cell wall on the biotransformation capability by recombinant Corynebacterium glutamicum cells, expressing the chnB gene encoding cyclohexanone monooxygenase of Acinetobacter calcoaceticus NCIMB 9871, were investigated. Baeyer-Villiger oxygenation of 2-(2'-acetoxyethyl) cyclohexanone (MW 170 Da) into R-7-(2'-acetoxyethyl)-2-oxepanone was used as a model reaction. The whole-cell biotransformation followed Michaelis-Menten kinetics. The V (max) and K (S) values were estimated as 96.8 U g(-1) of dry cells and 0.98 mM, respectively. The V (max) was comparable with that of cyclohexanone oxygenation, whereas the K (S) was almost eightfold higher. The K (S) value of 2-(2'-acetoxyethyl) cyclohexanone oxygenation was reduced by ca. 30% via altering the cell envelop structure of C. glutamicum with ethambutol, which inhibits arabinosyl transferases involved in the biosynthesis of cell wall arabinogalactan and mycolate layers. The higher whole-cell biotransformation rate was also observed in the oxygenation of ethyl 2-cyclohexanone acetate upon ethambutol treatment of the recombinant C. glutamicum. Therefore, it was assumed that the biotransformation efficiency of C. glutamicum-based biocatalysts, with respect to medium- to large-sized lipophilic organic substrates (MW > ca. 170), can be enhanced by engineering their cell wall outer layers, which are known to function as a formidable barrier to lipophilic molecules.
This study examined the mediating and moderating effects of family cohesion on the relationship between positive psychological capital and health promotion behaviors among dual working parents of young children during the COVID-19 pandemic. We collected data from 214 dual working parents and analyzed the results using the IMB SPSS version 26.0 software. We found that positive psychological capital had significant effects on both family cohesion (β = 0.19, p < 0.001) and health promotion behaviors (β = 0.26, p < 0.001), while family cohesion showed a significant mediating effect on health promotion behaviors (β = 0.34, p = 0.002). Positive psychological capital (independent variable) also had significant effects on health promotion behaviors (β = 0.19, p < 0.001). Finally, a Sobel test showed that family cohesion had a significant partial mediating effect on the relationship between positive psychological capital and health promotion behaviors (Z = 2.70, p = 0.005) but no moderating effect. Thus, it is necessary to enhance health promotion behaviors through programs focused on both family cohesion and positive psychological capital. However, the fact that participants in this study were only from South Korea highlights the requirement for future research that includes participants from different cultural contexts and social systems.
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