D-tagatose is a rare, naturally occurring low-calorie hexose, with a sweetness of 92% sucrose but only 1/3 of the calories. It has beneficial functions in lowering blood sugar, controlling obesity, preventing dental caries, and improving intestinal flora. In recent years, biotechnological routes to D-tagatose production from renewable raw materials have been regarded as very promising approaches. In this review, we provide an overview of the properties and applications of D-tagatose, with a focus on the current developments in the production of D-tagatose using enzymatic transformation and whole-cell catalytic synthesis. The biosynthetic pathways and the types and characteristics of the catalytic enzymes involved have been summarized, providing a reference for the design of D-tagatose synthesis pathways. We also expect that rapid developments in the fields of systems biology and synthetic biology will accelerate protein and metabolic engineering for microbial D-tagatose production in the future.

Root-knot nematodes induce the formation of feeding sites within the host roots and the relocation of auxin into galls results in abnormal lateral root growth. Here, we analyzed the changes in cucumber root architecture under Meloidogyne incognita stress and the distribution of auxin in these morphological and molecular root changes. The number of root tips significantly decreased, and regression analysis showed a positive relationship between the size of root galls and the numbers of nematodes in galls compared with the lateral roots on galls, emphasizing the effect of nematode parasitism on root development. Data generated via a promoter-reporter system using the transgenic hairy root system first characterized the auxin distribution during nematode parasitism in cucumber. Using DR5:GUS staining of root galls, we further detected the expression of CsPIN1 and CsAUX1, which regulate polar auxin transport. The results showed that both CsPIN1 and CsAUX1 were induced in galls, and the relative expression of the two genes significantly increased at 21 DAI. The TIBA treatment, which can disrupt polar auxin transport inhibited the numbers of cucumber root tips and total length following increasing concentration gradients. Moreover, the numbers of galls were significantly affected by TIBA treatment, which showed the vital role of auxin during nematode parasitism. Our findings suggest that the transportation of auxin plays an important role during gall formation and induces cucumber lateral root development within nematode feeding sites.

Plant growth-promoting rhizobacteria (PGPR) represent a sustainable and eco-friendly strategy to enhance crop productivity and support integrated agricultural systems. Among these, members of the genus Bacillus are highly valued for their resilience and multifaceted beneficial traits. The growth-promoting effects of Bacillus sp. L11 on S. lycopersicum seedlings were investigated in soil and artificial peat-based substrates. Rhizosphere microbial diversity was subsequently analyzed to investigate the interaction between L11 and the indigenous microbiota. We evaluated plant growth parameters, root growth parameters, and rhizosphere bacterial community dynamics using 16S rRNA high-throughput sequencing. Overall, L11 inoculation was associated with significantly improved growth indices of S. lycopersicum seedlings in both cultivation systems. Notably, the phosphate-buffered saline (PBS)-resuspended L11 markedly increased shoot fresh weight and plant height, and enhanced root-associated parameters such as total root length and root surface area. While L11 did not significantly alter alpha diversity, principal coordinates analysis (PCoA) revealed that its presence was associated with substantial restructuring of the rhizosphere bacterial community. Inoculation specifically enriched beneficial genera, including Chitinophaga, Devosia, and Pseudomonas. Correlation analyses showed that these microbial shifts were positively associated with the enhancement of seedling biomass and development. In conclusion, these findings suggest that Bacillus sp. L11 may promote S. lycopersicum growth through direct stimulation and by reshaping the rhizosphere microbiome, positioning it as a promising microbial inoculant for sustainable vegetable production.

Lignin is an abundant and renewable aromatic polymer, but its structural heterogeneity hinders its efficient bioconversion. Unlike previous reviews that focused on isolated topics such as single enzymes, pathway engineering, or specific bioproducts, this paper comprehensively reviews the latest advances in the structural characteristics, microbial degradation mechanisms, and bioconversion of lignin. Particular emphasis is placed on the catalytic mechanisms of key lignin-degrading enzymes, including laccase, lignin peroxidase (LiP), and manganese peroxidase (MnP), as well as the applications of fungi, bacteria, and synthetic microbial consortia in lignin bioconversion. Metabolic pathways that channel heterogeneous lignin-derived aromatics into central carbon metabolism through sequential catalytic reactions are also covered. Furthermore, we evaluate the emerging applications of artificial intelligence and machine learning in enzyme design and bioprocess control. Finally, techno-economic and life-cycle considerations are integrated to guide large-scale deployment. This review provides in-depth insights into the cross-scale translation from laboratory biocatalysis to industrial biorefineries.