Disrupting the olfactory response in Monochamus saltuarius: Two potential target genes for controlling the vector insect of pine wilt disease.

Worldwide, pine forests have been threatened by a devastating pine wood disease caused by Bursaphelenchus xylophilus, with Monochamus saltuarius being a newly recorded vector of the disease in Northeast China. The olfactory system plays important roles in both feeding and oviposition during the adult stage of M. saltuarius, and olfactory gene function research is essential for gaining an understanding of the olfactory mechanisms of this pest. However, there is limited information available regarding olfactory gene functions in this pest. In the present study, we selected 7 olfactory genes, including 2 chemosensory proteins, 2 odorant-binding proteins, the odorant co-receptor and 2 odorant receptors, which were relatively highly expressed during the adult stage. We silenced these genes by RNA interference (RNAi), and real-time quantitative PCR was used to detect their expression levels after double-stranded RNA (dsRNA) injection. The results indicate that these genes were significantly downregulated at 2 d post-dsRNA injection, and this was sustained until 5 d post-injection. Electroantennography tests indicated that the knockdown of MsalOBP14 and MsalOrco impaired the olfactory response of M. saltuarius to 11 host volatiles and 1 sex pheromone compound. Y-tube experiments further confirmed that downregulated MsalOBP14 and MsalOrco expression led to olfactory dysfunction in M. saltuarius, which significantly lost selectivity. The results indicate that MsalOBP14 and MsalOrco play critical roles in sex communication and host volatile detection in M. saltuarius, and possibly represent 2 effective targets for controlling this forest pest through olfactory disruption.

Induction of antiherbivore defense responses in poplars using a methyl jasmonate and mesoporous silica nanoparticle complex.

BACKGROUND: Poplar in China has long been plagued by the fall webworm Hyphantria cunea. Enhancing plant immunity using chemical elicitors is an environmentally friendly approach to pest control. The phytohormone methyl jasmonate (MeJA) can stimulate the chemical defenses of poplars against herbivores but has been shown to have limited efficacy in practice. Here, we studied the effects of a MeJA and mesoporous silica nanoparticle (MSN) complex (MeJA@MSN) regarding the induction of poplar resistance to H. cunea, which may provide strategies for the effective use of MeJA. RESULTS: The silicon-based phytohormone complex (MeJA@MSNs) exhibited excellent biological and physiochemical properties, such as excellent biocompatibility and plant tissue transportability. The changes in metabolites in poplar leaves induced by MeJA, MSNs, and MeJA@MSNs were investigated by metabolic analysis. MeJA@MSNs led to highly potent induced resistance along with elevated salicylaldehyde content, which increased with the dose administered. The salicylaldehyde metabolite showed a strong antifeedant effect on H. cunea larvae at a dosage of 1 µg, with the 50% lethal dose being 20.4 µg/mg. Furthermore, transcriptional analysis showed that MeJA@MSNs upregulated key genes in biosynthetic pathways more than MeJA and MSNs. CONCLUSION: Our results show that MeJA and MSNs interact positively in poplar, leading to salicylaldehyde accumulation and increased induced resistance to H. cunea, providing new insights into the underlying resistance mechanisms induced by MeJA@MSNs. © 2024 Society of Chemical Industry.

Fuzheng Huayu recipe inhibits bleomycin-induced pulmonary fibrosis in rats by inhibiting M2 polarization of macrophages via the oxidative phosphorylation pathway.

Fuzheng Huayu recipe (FZHYR) is a Chinese patent medicine for the treatment of fibrosis. The effects of FZHYR on pulmonary fibrosis and macrophage polarization were investigated in vitro. FZHYR inhibited pulmonary inflammation and fibrosis and M2 polarization of macrophages in bleomycin-induced pulmonary fibrosis (BPF) of rat model. Differentially expressed genes were screened by high-throughput mRNA sequencing and GSEA showed that oxidative phosphorylation (OXPHOS) was correlated with BPF. FZHYR inhibited expressions of Ndufa2 and Ndufa6 in lung tissues of BPF rats. These findings suggest that OXPHOS pathway serves as a possible target for pulmonary fibrosis therapy by FZHYR.

Analysis of volatiles from the thermal decomposition of Amadori rearrangement products in the cysteine-glucose Maillard reaction and density functional theory study.

The Amadori rearrangement products are an important flavor precursor in the Maillard reaction. Its thermal decomposition products usually contribute good flavors in foods. Therefore, investigating the thermal breakdown of Amadori products is significant for understanding the flavor forming mechanism in the Maillard reaction. In this study, volatiles from thermal decomposition of Amadori products in cysteine and glucose Maillard reaction was investigated by a thermal desorption cryo-trapping system combined with gas chromatography-mass spectrometry (GC-MS). A total of 60 volatiles were detected and identified. Meanwhile, the forming mechanism of 2-methylthiophene, a major decomposition product, was also investigated by using density functional theory. Seventeen reactions, 12 transition states, energy barrier and rate constant of each reaction were finally obtained. Results reveal that it is more likely for Amadori products of cysteine and glucose to undergo decomposition under neutral or weakly alkaline conditions.

The effects of Lactiplantibacillus plantarum 3-19 and Pediococcus pentosaceus 18-1 on preventing the accumulation of biogenic amines and promoting the production of volatile organic compounds during sour meat fermentation.

Lactic acid bacteria (LAB) are frequently used in meat fermentation, and mixed stater cultures are reported to perform better than single ones. Lactiplantibacillus plantarum 3-19 and Pediococcus pentosaceus 18-1 were chosen from 28 sour-meat-origin strains to examine the effects of single and combined inoculation on sour meat quality. Natural fermentation was used as a control to investigate changes in pH, water activity (aw), amino acid nitrogen (AN), texture, microbial diversity, and volatile organic compounds (VOCs) during fermentation. The pH and aw of each inoculation group were significantly decreased, and AN content was significantly increased. The inoculation of P. pentosaceus 18-1 significantly reduced putrescine, cadaverine, and tryptamine content (p < 0.05), while the inoculation of Lpb. plantarum 3-19 significantly reduced cadaverine amounts (p < 0.05). At the fermentation endpoint, the total biogenic amines content in the C group was 992.96 ± 14.07, which was 1.65, 2.57, and 3.07 times higher than that in the Lp, Pe, and M groups, respectively. The mixed inoculation group combined the advantages of both strains and decreased total biogenic amines most significantly. At the end of fermentation, the VOCs in C, Lp, Pe, and M groups were 10.11, 11.56, 12.45, and 13.39 times higher than those at the beginning of fermentation. Inoculation promoted the production of key VOCs (OAV > 2000) such as heptanal, octanal, and (E)-2-nonanal. The mixed inoculation group had the highest variety and content of VOCs and the highest content of the above key VOCs, significantly enhancing its fruity, floral, ester, and other aromas. Sensory evaluation indicated that the M group had the best overall acceptability. Finally, it was suggested that a combination of Lpb. plantarum 3-19 and P. pentosaceus 18-1 is a novel and efficient starter culture for processing sour meat since they lower the amounts of biogenic amines in the meat and promote the production of VOCs.

Function of MYB8 in larch under PEG simulated drought stress.

Larch, a prominent afforestation, and timber species in northeastern China, faces growth limitations due to drought. To further investigate the mechanism of larch's drought resistance, we conducted full-length sequencing on embryonic callus subjected to PEG-simulated drought stress. The sequencing results revealed that the differentially expressed genes (DEGs) primarily played roles in cellular activities and cell components, with molecular functions such as binding, catalytic activity, and transport activity. Furthermore, the DEGs showed significant enrichment in pathways related to protein processing, starch and sucrose metabolism, benzose-glucuronic acid interconversion, phenylpropyl biology, flavonoid biosynthesis, as well as nitrogen metabolism and alanine, aspartic acid, and glutamic acid metabolism. Consequently, the transcription factor T_transcript_77027, which is involved in multiple pathways, was selected as a candidate gene for subsequent drought stress resistance tests. Under PEG-simulated drought stress, the LoMYB8 gene was induced and showed significantly upregulated expression compared to the control. Physiological indices demonstrated an improved drought resistance in the transgenic plants. After 48 h of PEG stress, the transcriptome sequencing results of the transiently transformed LoMYB8 plants and control plants exhibited that genes were significantly enriched in biological process, cellular component and molecular function. Function analyses indicated for the enrichment of multiple KEGG pathways, including energy synthesis, metabolic pathways, antioxidant pathways, and other relevant processes. The pathways annotated by the differential metabolites mainly encompassed signal transduction, carbohydrate metabolism, amino acid metabolism, and flavonoid metabolism.

Novel microbial fermentation for the preparation of iron-chelating scallop skirts peptides-its profile, identification, and possible binding mode.

Iron chelating peptides have been widely utilized as iron supplements due to their excellent absorption capacity, However, the high cost and cumbersome manufacturing process of these peptides significantly limit their industrial application. In this study, fermentation was used for the first time to prepare iron chelating peptides. Bacillus altitudinis 3*1-3 was selected as the most suitable strain from 50 strains. The hydrolysates of fermented scallop skirts showed excellent iron-chelating capacity (9.39 mg/g). Aspartic acid, glutamic acid, and histidine are crucial for the binding of peptides to ferrous ions. The heptapeptide (FEDPEFE) forms six binding bonds with ferrous irons. Compared with ferrous sulfate, peptide-ferrous chelate showed more stability in salt solution and simulated gastrointestinal juice (p < 0.05). Furthermore, the fermentation method could save >50% of the cost compared with the enzymatic method. The results can provide a theoretical basis for the preparation of ferrous-chelated peptides using the fermentation method.

Effects of quercetin- and Lactiplantibacillus plantarum-containing bioactive films on physicochemical properties and microbial safety of grass carp.

In this study, the electrospinning technique was used to co-encapsulate Quercetin (Qu) and Lactiplantibacillus plantarum 1-24-LJ in PVA-based nanofibers, and the effect of bioactive films on fish preservation was evaluated at the first time. The findings indicated that both Lpb. plantarum 1-24-LJ and Qu were successfully in the fibers, and co-loaded fibers considerably outperformed single-loaded fiber in terms of bacterial survival and antioxidant activity. Following fish preservation using the loaded fibers, significant reductions were observed in TVB-N, TBARS, and microbial complexity compared to the control group. Additionally, the co-loaded fibers more effectively reduced the counts of H2S-producing bacteria and Pseudomonas. In the future, fibers with both active substances and LAB hold promise as a novel approach for fish preservation.

Molecular mechanism of saturated aldehyde oxidation: A DFT insight into volatiles forming from decanal thermal oxidation.

Decanal is one of the main products of lipid oxidation. It has been shown that decanal can oxidize to form volatiles with shorter carbon chains during heating, but the mechanism is still unclear. In this study, volatile compounds formed in the decanal thermal oxidation were verified using thermal-desorption cryo-trapping combined with GC-MS. A total of 32 volatile compounds were identified. The oxidation mechanism of decanal was studied by applying density functional theory. Results revealed that the carbonyl carbon atom was the thermal oxidation site of decanal and two pathways of peroxide oxidation were determined: the ortho­carbon and the meta­carbon oxidation. The ortho­carbon oxidation pathway is superior to the occurrence of the meta­carbon oxidation pathway. The oxidative mechanism of decanal was finally summarized as the peroxide oxidation based on radical attack on the carbonyl carbon, which would provide a theoretical basis for exploring the oxidation mechanism of other saturated aldehydes.

Analysis of Fungal Diversity, Physicochemical Properties and Volatile Organic Compounds of Strong-Flavor Daqu from Seven Different Areas.

Strong-flavor Daqu, as a fermentation agent, plays a significant role in shaping the quality of strong-flavor baijius, and fungal species in Daqu are important factors affecting the quality of Daqu. Therefore, we selected strong-flavor Daqu from seven different origins to study the fungal composition and the effects of the fungal composition on the physicochemical properties and volatile organic compounds (VOCs). It was found that the fungal composition influences the physicochemical properties of Daqu. Specifically, there was a positive link between Rhizomucor, Rhizopus, Thermomyces, and liquefying activity and a positive correlation between Aspergillus and fermenting activity. Furthermore, the relationships between esterifying activity and Thermomyces, Rhizomucor, Aspergillus, Pichia, and Saccharomycopsis were found to be positive. The VOCs in Daqu were affected by Aspergillus, Issatchenkia, Pichia, and Thermoascus. Issatchenkia was significantly positively correlated with benzeneethanol as well as Aspergillus and pentadecanoic acid ethyl ester, ethyl myristate. Pichia and Thermoascus were significantly negatively correlated with benzaldehyde and 2-furaldehyde. This study deepens our understanding of the relationship between VOCs, the physicochemical properties with microbial communities, and reference significance for the production of better-quality strong-flavor Daqu.

Lactiplantibacillus plantarum A72, a Strain with Antioxidant Properties, Obtained through ARTP Mutagenesis, Affects Caenorhabditis elegans Anti-Aging.

This research endeavored to elucidate the antioxidant attributes of lactic acid bacteria, specifically their impact on anti-aging and lifespan augmentation in Caenorhabditis elegans. The study focused on Lactiplantibacillus plantarum A72, identified through ARTP mutagenesis for its potent antioxidant properties. In vitro analysis affirmed its free radical neutralizing capacity. In C. elegans, the strain not only extended the lifespan by 25.13% and amplified motility 2.52-fold, but also maintained reproductive capabilities. Remarkably, Lpb. plantarum A72 diminished reactive oxygen species (ROS) and malondialdehyde (MDA) levels in C. elegans by 34.86% and 69.52%, respectively, while concurrently enhancing its antioxidant enzyme activities. The strain also bolstered C. elegans survival rates by 46.33% and 57.78% under high temperature and H2O2 conditions, respectively. Transcriptomic scrutiny revealed that Lpb. plantarum A72 could retard C. elegans aging and extend lifespan by upregulating the sod-5 and hsp-16.1 genes and downregulating the fat-6 and lips-17 genes. These findings propose Lpb. plantarum A72 as a potential antioxidant and anti-aging lactic acid bacteria.

Production optimization of food functional factor ergothioneine in wild-type red yeast Rhodotorula mucilaginosa DL-X01.

BACKGROUND: Ergothioneine (EGT) is a high-value food functional factor that cannot be synthesized by humans and other vertebrates, and the low yield limits its application. RESULTS: In this study, the optimal fermentation temperature, fermentation time, initial pH, inoculum age, and inoculation ratio on EGT biosynthesis of Rhodotorula mucilaginosa DL-X01 were optimized. In addition, the effects of three key precursor substances - histidine, methionine, and cysteine - on fungal EGT synthesis were verified. The optimal conditions were further obtained by response surface optimization. The EGT yield of R. mucilaginosa DL-X01 under optimal fermentation conditions reached 64.48 ± 2.30 mg L-1 at shake flask fermentation level. Finally, the yield was increased to 339.08 ± 3.31 mg L-1 (intracellular) by fed-batch fermentation in a 5 L bioreactor. CONCLUSION: To the best of our knowledge, this is the highest EGT yield ever reported in non-recombinant strains. The fermentation strategy described in this study will promote the efficient biosynthesis of EGT in red yeast and its sustainable production in the food industry. © 2024 Society of Chemical Industry.

Mechanism of thermal oxidation into volatile compounds from (E)-4-decenal: A density functional theory study.

Unsaturated aliphatic aldehyde oxidation plays a significant role in the deep oxidation of fatty acids to produce volatile chemicals. Exposing the oxidation process of unsaturated aliphatic aldehydes is crucial to completely comprehend how food flavor forms. In this study, thermal desorption cryo-trapping in conjunction with gas chromatography-mass spectrometry was used to examine the volatile profile of (E)-4-decenal during heating, and 32 volatile compounds in all were detected and identified. Meanwhile, density functional theory (DFT) calculations were used, and 43 reactions were obtained in the 24 pathways, which were summarized into the peroxide reaction mechanism (ROOH), the peroxyl radical reaction mechanism (ROO·) and the alkoxy radical reaction mechanism (RO·). Moreover, the priority of these three oxidative mechanisms was the RO· mechanism > ROOH mechanism > ROO· mechanism. Furthermore, the DFT results and experimental results agreed well, and the oxidative mechanism of (E)-4-decenal was finally illuminated.

Inoculation of Yarrowia lipolytica promotes the growth of lactic acid bacteria, Debaryomyces udenii and the formation of ethyl esters in sour meat.

Yarrowia lipolytica N12 and A13 with high lipase activity obtained by mutagenesis were inoculated into sour meat, and their effects on physicochemical properties, microbial community succession, free amino acids, and volatile compounds of sour meat were investigated. Inoculation fermentation increased the contents of free amino acids observably, rapidly reduced pH, promoted the accumulation of total acids, decreased 2-thiobarbituric acid reactive substances (TBARS) values. In addition, the addition of Y. lipolytica might contribute to the growth of lactic acid bacteria, Candida spp., and Debaryomyces udenii, which play an important role in production of volatile compounds. It was shown that inoculation promoted the production of esters, aldehydes, and alcohols, especially ethyl esters, giving sour meat a better meat flavor. Besides, it was found that Y. lipolytica A13 had better fermenting property. Sample of A13 group had higher contents of ethyl esters, free amino acids and dominant microorganisms. The results may help to provide new strains for sour meat fermentation.