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Lavender species are of significant economic value being cultivated extensively worldwide for their essential oils (EOs), which include terpenes that play crucial roles in the cosmetic, personal care, and pharmaceutical industries. The terpene synthases in lavender, such as Lavandula angustifolia linalool synthase (LaLINS), limonene synthase (LaLIMS), and bergamotene synthase (LaBERS), are key enzymes in terpene biosynthesis. However, the functional mechanisms underlying these enzymes remain poorly understood. Here, we used AlphaFold2 to predict the three-dimensional structures of LaLINS, LaLIMS, and LaBERS. The hydrodynamic radii of LaLINS, LaLIMS, and LaBERS were 5.7 ± 0.2, 6.2 ± 0.3, and 5.4 ± 0.2 nm, respectively. Mutations D320A or D324A led to a complete loss of activity in LaLINS compared to the wild-type (WT) enzyme; similarly, mutations D356A or D360A abolished activity in LaLIMS, and D291A or D295A eliminated activity in LaBERS. Furthermore, the genes LaLINS, LaLIMS, and LaBERS exhibited significantly higher expression levels in leaves compared to stems and flowers, with peak expression occurring at 8:00 a.m. Our findings contribute to a deeper understanding of terpene biosynthesis in lavender and offer insights for improving essential oil production through genetic engineering.

This study aimed to investigate the impact of incorporating mature compost on the harmlessness and maturity level of composting from swine manure and carcasses from industrialized pig farms in continuously running large-scale silo reactor systems. The potential human or animal bacterial pathogens and core bacterial community in composting were analyzed by high-throughput sequencing of 16S rRNA gene amplicons. The results showed that the addition of mature compost in the GD group significantly increased the temperature of all depths, the accumulated temperature of compost, and the germination index (75.43%) compared to that in the HN group without mature compost. High-throughput sequencing revealed that the dominated genera in GD were Ureibacillus, Lactobacillus, Corynebacterium, Staphylococcus, and Jeotgalicoccus, and the addition of mature compost could significantly increase the relative abundance of Ureibacillus (16.82%) that was associated with the biodegradation of organics. A total of 421 potential bacterial pathogens were detected, and the dominated genera of pathogens were Streptococcus, Staphylococcus, and Anaerococcus. The potential pathogen in the GD group with mature compost was reduced from 7.16 to 0.77%, which was significantly lower than that (2.97%) in the HN group. Together, these findings revealed that mature compost addition in large-scale reactor composting could accelerate the harmless and humification process, providing an effective and environmentally friendly scheme to deal with the main organic wastes in intensive pig farms.

Objective: To establish a rapid detection method for viable Penicillium expansum by propidium monoazide (PMA) combined with quantitative real-time polymerase chain reaction (qPCR). Methods: PMA-qPCR detection method for viable P. expansum was established, including the optimization of the treatment concentration, dark incubation and exposure time of PMA, the screening of specific primers of P. expansum, and the conduction of qPCR. In addition, the standard curve was constructed, which was applied to the detection of artificially contaminated apples samples. The reliability of this method was also evaluated by comparing with the plate counting method. Results: The optimal PMA treatment conditions were: 10 µg/mL for PMA concentration, 5 min for the dark incubation and 10 min for the exposure time. Among the 4 pairs of primers, Pexp-patF showed strong specificity for P. expansum, which could be used as a optimal primer for PMA-qPCR detection. The correlation coefficient of the established quantitative standard curve was 0.9948, and the detection limit of the method was 102.6 CFU/mL. There was no obvious difference between the detection result of this method and the plate counting method, and the viable P. expansum could be detected in the non-rotted part of apples. Conclusion: The established PMA-qPCR technique could be applied to the detection of P. expansum in apples, which would provide technical support for the prevention and control of P. expansum.

Alternaria spp. and its toxins are the main contaminants in processing tomato. Based on our earlier research, the current study looked into the anti-fungal capacity of crude lipopeptides from B. amyloliquefaciens XJ-BV2007 against A. alternata. We found that the crude lipopeptides significantly inhibited A. alternata growth and reduced tomato black spot disease incidence. SEM analysis found that the crude lipopeptides could change the morphology of mycelium and spores of A. alternata. Four main Alternaria toxins were detected using UPLC-MS/MS, and the findings demonstrated that the crude lipopeptides could lessen the accumulation of Alternaria toxins in vivo and in vitro. Meanwhile, under the stress of crude lipopeptides, the expression of critical biosynthetic genes responsible for TeA, AOH, and AME was substantially down-regulated. The inhibitory mechanism of the crude lipopeptides was demonstrated to be the disruption of the mycelial structure of A. alternata, as well as the integrity and permeability of the membrane of A. alternata sporocytes. Taken together, crude lipopeptides extracted from B. amyloliquefaciens XJ-BV2007 are an effective biological agent for controlling tomato black spot disease and Alternaria toxins contamination.

We analyzed the complete mitochondrial genome of the recently discovered Xinyuan honey bee, Apis mellifera sinisxinyuan using single molecule real-time sequencing. The mitochondrial genome of A. m. sinisxinyuan is a circular molecule of 16,886 bp, comprising 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes and a control region rich in A + T. Phylogenetic analysis using 13 protein-coding genes supports a close relationship to another M-lineage honey bee, A. m. mellifera.

Rahnella aquatilis strain HX2 has the ability to promote maize growth and suppress sunflower crown gall disease caused by Agrobacterium vitis, A. tumefaciens, and A. rhizogenes. Pyrroloquinoline quinone (PQQ), a cofactor of aldose and alcohol dehydrogenases, is required for the synthesis of an antibacterial substance, gluconic acid, by HX2. Mutants of HX2 unable to produce PQQ were obtained by in-frame deletion of either the pqqA or pqqB gene. In this study, we report the independent functions of pqqA and pqqB genes in relation to PQQ synthesis. Interestingly, both the pqqA and pqqB mutants of R. aquatilis eliminated the ability of strain HX2 to produce antibacterial substance, which in turn, reduced the effectiveness of the strain for biological control of sunflower crown gall disease. The mutation also resulted in decreased mineral phosphate solubilization by HX2, which reduced the efficacy of this strain as a biological fertilizer. These functions were restored by complementation with the wild-type pqq gene cluster. Additionally, the phenotypes of HX2 derivatives, including colony morphology, growth dynamic, and pH change of culture medium were impacted to different extents. Our findings suggested that pqqA and pqqB genes individually play important functions in PQQ biosynthesis and are required for antibacterial activity and phosphorous solubilization. These traits are essential for R. aquatilis efficacy as a biological control and plant growth promoting strain. This study enhances our fundamental understanding of the biosynthesis of an environmentally significant cofactor produced by a promising biocontrol and biological fertilizer strain.

Rahnella aquatilis strain HX2 is a plant growth-promoting, disease-suppressive rhizobacterium that was isolated from a vineyard soil in Beijing, China. Here, we report the genome sequence of this strain, which provides a valuable resource for future research examining the mechanisms of traits associated with plant growth promotion and biocontrol. [ABSTRACT FROM AUTHOR]