In this study, yeast strains were screened and immobilized in a form preserving the multifaceted biocatalytic activity. Im-mobilization of the silica-supported whole-cells of various yeasts – such as Lodderomyces elongisporus, Pichia carsonii, Candida norvegica and Debaryomyces fabryi – by sol-gel entrapment resulted in easy-to-handle biocatalysts that mediated efficiently different types of synthetic reactions. In the present study, the enantiotope selective reduction of prochiral ke-tones 1a-d and the acyloin condensation of benzaldehyde 3 were studied representing two remarkably diverse types of bio-transformation. The yeast cell biocatalysts – in the presence of fresh or recovered NADH cofactor – could be applied for continuous-flow bioreduction of ketones 1a,b with moderate to good yields (20 to 92%) and excellent enantiomeric purity (>99%). Immobilized L. elongisporus and P. carsonii cells could also mediate acyloin condensation of benzaldehyde 3 in batch as well as in continuous-flow mode. The switchable biocatalytic activity of the immobilized yeast cells was demon-strated by consecutive biotransformations under continuous-flow conditions involving reduction of phenylacetone 1a to (S)-phenylpropane-2-ol (S)-2a first, followed by conversion of benzaldehyde 3 to (R)-1-hydroxy-1-phenylpropan-2-one (R)-4 and reduction of 1a to (S)-2a again by using the same packed bed bioreactor.

Tomato fruit (Solanum lycopersicum) is a valuable agricultural crop worldwide due to its nutritional value and culinary applications, making it one of the most widely consumed vegetables in the human diet. However, excessive solar UV-B radiation represents a significant factor in decreasing productivity, marketable yields, and fruit quality in tomato crops by causing damage to both DNA and the photosynthetic system, as well as chlorophyll degradation. The application of silicon nanoparticles has been shown to increase tolerance to abiotic stressors, including enhanced UV-B radiation. Therefore, this study aims to evaluate the protective effects of foliar silicon nanoparticle (SiNP) application on photosynthetic parameters, photosynthetic pigments, and secondary metabolites under enhanced UV-B stress in tomato plants. Photosynthetic parameters (stomatal conductance to water vapor, net CO₂ assimilation rate, transpiration rate, and intercellular CO₂ molar fraction), biogenic volatile organic compounds (BVOCs), chlorophylls, and carotenoids were evaluated. The application of SiNPs showed beneficial effects on plants grown under ambient UV-B conditions, increasing photosynthetic parameters while also enhancing chlorophyll and carotenoid levels. In plants exposed to enhanced UV-B radiation, SiNP treatment helped to maintain and even improve photosynthetic parameters and stomatal function in leaves while also promoting the accumulation of photosynthetic pigments. Additionally, the application of SiNPs also resulted in a slightly higher content of lycopene and total carotenoids in tomato fruits.

Background/Objectives: α-Hydroxy ketones (acyloins) are valuable chiral building blocks widely used in the synthesis of pharmaceuticals and fine chemicals. Their stereoselective synthesis remains challenging, driving interest in sustainable biocatalytic approaches for asymmetric C–C bond formation. Methods: Here, non-conventional yeasts (NCYs) from six genera were evaluated as lyophilized whole-cell biocatalysts for acyloin production through carboligase-mediated synthesis. Results: Four strains—Pichia carsonii WY-1, Lodderomyces elongisporus WY-2, and Candida guilliermondii WY-7 and WY-8—exhibited high carboligase activity when pyruvate was used as co-substrate, efficiently converting benzaldehyde and pyruvate to (R)-PAC. Factorial design screening of reaction conditions (pH, co-substrate concentration, and temperature) minimized byproduct formation, yielding (R)-PAC in 79–96% yield and 97.6–98.3% ee. Evaluating a substrate scope of 30 functionalized aromatic aldehydes revealed broad native tolerance, particularly toward meta- and para-substituted derivatives, affording corresponding α-hydroxy ketones in 10–90% yield and generally >90% ee. Conclusions: These results demonstrate the potential of lyophilized NCYs as whole-cell biocatalysts for stereoselective acyloin synthesis. Furthermore, these strains serve as promising sources of new enzymes with carboligase activity for future biochemical exploration and biocatalyst development.