Ethyl esters of omega-3 fatty acids are active pharmaceutical ingredients used for the reduction in triglycerides in the treatment of hyperlipidemia. Herein, an ultrasonic packed-bed bioreactor was developed for continuous production of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) ethyl esters from DHA+EPA concentrate and ethyl acetate (EA) using an immobilized lipase, Novozym^® 435, as a biocatalyst. A three-level–two-factor central composite design combined with a response surface methodology (RSM) was employed to evaluate the packed-bed bioreactor with or without ultrasonication on the conversion of DHA + EPA ethyl ester. The highest conversion of 99% was achieved with ultrasonication at the condition of 1 mL min⁻¹ flow rate and 100 mM DHA + EPA concentration. Our results also showed that the ultrasonic packed-bed bioreactor has a higher external mass transfer coefficient and a lower external substrate concentration on the surface of the immobilized enzyme. The effect of ultrasound was also demonstrated by a kinetic model in the batch reaction that the specificity constant (V′max/K₂) in the ultrasonic bath was 8.9 times higher than that of the shaking bath, indicating the ultrasonication increased the affinity between enzymes and substrates and, therefore, increasing reaction rate. An experiment performed under the highest conversion conditions showed that the enzyme in the bioreactor remained stable at least for 5 days and maintained a 98% conversion.

Combining microbial products with different mechanisms of action can produce synergistic insecticidal effects and slow down the development of resistance. This study evaluated the insecticidal activity of mixtures containing the commercial Photorhabdus luminescens (Pl) strain ATCC 29,999, the local isolate Pl 2103-UV, and the commercial Bacillus thuringiensis subsp. kurstaki (Bt) ABTS-351 against Spodoptera frugiperda. As the proportion of Bt increased in the mixtures, insecticidal activity increased, with the synergistic ratios reaching 1.98 for ATCC 29,999 and 5.29 for 2103-UV at a1:5 Pl:Bt ratio, representing approximately twofold and fivefold reductions, respectively, in the Bt dosage required for mortality. Hemolymph analysis revealed the highest Pl bacterial loads in the 1:5 treatments within the S. frugiperda hemocoel. Histopathology also showed exacerbated midgut vacuolation in the 1:5 ATCC 29,999:Bt treatment. Whole-genome analysis showed that 2103-UV produced more porins, potentially contributing to its higher insecticidal activity. This study demonstrated that Bt assists the invasion of Pl into the hemocoel and enhances synergistic insecticidal efficiency. The findings provide a reference for integrating Pl with other microbial products to sustainably manage significant and severe lepidopteran pests.

Background: Plutella xylostella is a major pest of cruciferous vegetables worldwide. We evaluated a biopesticide using different culture treatments of Photorhabdus luminescens (ATCC 29,999) and Bacillus thuringiensis subsp. aizawai and examined their insecticidal activity against Pl. xylostella. Methods: L₈ and L₉ Taguchi orthogonal designs were adopted to evaluate the optimal culture medium for enhanced insecticidal activity. Feeding bioassays were conducted to determine the potential synergistic effects of combining B. thuringiensis and Ph. luminescens, and the most effective synergistic combination was identified by analyzing the time–mortality response against Pl. xylostella. Significant Findings Analysis of the pH value indicates that Ph. luminescens has enhanced tolerance to acidic conditions and can alkalize the medium. Among the various medium combinations, Ph. luminescens optimized using A3B1C3N2—d10 × concentration, 24-h cultivation time, 1.25 % molasses as the carbon source, and a nitrogen source consisting of yeast extract powder, yeast powder, and amino acids (0.2:0.3:0.5 %)—resulted in the highest insect mortality. Synergistic interactions between B. thuringiensis and Ph. luminescens were observed in the 1:1 mixture, likely due to immune system suppression. These results highlight the potential of combining Ph. luminescens and B. thuringiensis to prepare a potent bioinsecticide against Pl. xylostella and other lepidopteran pests, thereby decreasing the reliance on chemical pesticides.