农林科学最新文献

Fungal hyphae self-assemble a variety of cellular macrostates, ranging from suspended mycelium to dense pellets, all inextricably linked to their productivity. In this study, using CRISPR/Cas technology, we constructed a ctnA knockout strain (ΔctnA) and an overexpression strain (A2) so as to investigate the effects of interfering with citrinin biosynthesis on the growth, morphology and pigmentation of M.purpureus. Results indicated that deletion of ctnA in M. purpureus RP2 led to increased mycelium length, delayed conidium formation, and a citrinin content of 22% of the wild-type strain. Conversely, ctnA overexpression in strain A2 resulted in delayed mycelial growth, normal conidium formation, and a citrinin content of 120% compared to the wild-type strain, with minimal effects on pigments content. Notably, the ΔctnA strain formed small, tightly structured pellets (mean diameter 1.2 ± 0.06 mm) and exhibited low citrinin content, promoting pigments production. Our findings suggest a complex interplay between citrinin biosynthesis and morphological development, providing insights for optimizing metabolite production in industrial applications.

The probiotic effects of lactic acid bacteria make them widely used in human and animal breeding industry. However, the presence of oxidative stress during the production and application process can cause bacterial damage or even death, significantly compromising the functionality of probiotics. Despite its potential for broader application scenarios that could provide a more comprehensive understanding of bacteria's internal adaptation strategies, there is a lack of research investigating oxidative stress from the perspective of culture methods. In this study, the tolerance to oxidative stress was compared between bacteria cultivated through solid-state fermentation (SSF) and liquid-state fermentation (LSF), and the physiological and transcriptional disparities between these two bacterial strains were investigated. Additionally, a novel and efficient gene editing method was developed to elucidate the genetic basis underlying these differences in tolerance. The results demonstrated a significantly higher tolerance to oxidative stress in SSF bacteria compared to LSF bacteria, along with a stronger capacity for maintaining intracellular microenvironment stability and the activity of key metabolic enzymes. It is noteworthy that the bacteria from SSF significantly enhance the transport of carbohydrate substances and facilitate intracellular metabolic flow. Gene editing experiments have confirmed the crucial role of genes glpF and glpO in regulating the glycerol metabolism pathway, which is essential for enhancing the tolerance of bacteria from SSF to oxidative stress. Based on these findings, the mechanism underlying the disparity in oxidative stress tolerance resulting from different culture methods has been summarized. Furthermore, investigation into different culture modes has revealed that moderate oxygen levels during cultivation significantly influence variation in bacterial tolerance to oxidative stress. Importantly, these variations are species-specific and depend on the ecological niche distribution of Lactobacilli. These findings elucidate a novel mechanism by which Lacticaseibacillus paracasei Zhang tolerates oxidative stress, and also suggest that distinct cultivation and processing methods should be tailored based on the specific Lactobacilli groups to achieve optimal application effects in production.

This study evaluated the interactions between single or dual-species biofilms formed by dominant spoilage bacteria P. weihenstephanensis and M. caseolyticus isolated from refrigerated, spoilage prepared beef steaks at 4 °C and elucidated the interactive behavior of biofilm development in dual species. In addition, the relationship between biofilm formation capacity and cross-contamination was analyzed by simulating surface to food contact transfer. The results showed that the two species exhibited synergism as biofilms developed, which was the main mode of interaction observed. Under aerobic conditions, Pseudomonas weihenstephanensis and Macrococcus caseolyticus co-cultured for 96 h showed obvious biofilm formation ability, resulting in greater cross-contamination. Scanning electron microscopy and Confocal laser scanning microscopy showed the formation of flattened dense biofilms in the co-culture. The significant increase in Fe content and decrease in siderophore content of the dual-species biofilm as determined by ICP-MS was attributed to respiratory inhibition resulting in a decrease in the transcription of genes regulating the two-component regulatory system of Macrococcus tyrolyticus SrrAB and an increase in the expression of cytoplasmic hydrolase leading to the rupture of the release of hemoglobin to provide a source of iron for P. weihenstephanensis. The increase of heme content in the supernatant of dual-species and the results of RT-qPCR showed that the gene expression of the heme transport system of P. weihenstephanensis was significantly up-regulated and the siderophore gene expression was decreased, which further revealed that P. weihenstephanensis preferentially uses the heme uptake system to take up the iron source provided by M. caseolyticus for P. weihenstephanensis. Overall, our results provide insight into the complex dynamics of biofilms formed by P. weihenstephanensis and M. caseolyticus, emphasizing that the iron reaction pathway may be a key factor influencing the growth of P. weihenstephanensis biofilms, and that these results will provide a theoretical basis for the control of spoilage of refrigerated foods.

Lactic acid bacteria (LAB), principally Oenococcus oeni, play crucial roles in wine production, contributing to the transformation of L-malic acid into L-lactic acid during malolactic fermentation (MLF). This fermentation is influenced by different factors, including the initial LAB population and wine stress factors, such as nutrient availability. Yeast mannoproteins can enhance LAB survival in wine. This study explored in model conditions the impact of a commercial mannoprotein extract on MLF dynamics in ten O. oeni strains. The results revealed strain-specific responses in fermentation kinetics and mannoprotein utilization. Mannoprotein addition influenced MLF outcomes, depending on the strain and concentration. The variability in MLF confirmed different technological aptitude of the strains used. The α-mannosidase enzymatic activity was determined and showed higher values in the supernatant than in whole cells. Moreover, α-mannosidase activity varied among strains, suggesting differential regulation in response to fermentation conditions. These findings highlight the importance of understanding mannoprotein interactions with O. oeni for optimizing MLF efficiency and enhancing wine quality. Further research under cellar conditions is needed to evaluate the potential of yeast mannoproteins to promote MLF.

Lipid metabolism plays an important role in the regulation of early embryonic development in mammals. However, the effect of lipid metabolism mediated by peroxisome proliferator-activated receptor γ (PPARγ) on the early embryonic development of sheep remains unclear. In this study, rosiglitazone (RSG), a PPARγ activator, was added to the in vitro embryo culture (IVC) medium to regulate the continuous expression of PPARγ. This study aimed to evaluate PPARγ expression during early embryonic development in sheep as well as its effects on lipid deposition, reactive oxygen species (ROS) and glutathione (GSH) levels, apoptosis and lipid metabolism-related gene expression, and embryonic development. PPARγ was not detected at 2-cell, 4-cell, 8-cell, and morula stage, while widely expressed with obvious nuclear expression features in blastocysts. Notably, treatment with 5 μM RSG in sheep parthenogenetic activated (PA) embryos significantly increased the blastocyst rate, lipid content, and GSH levels, while decreasing ROS levels. Further analysis revealed that RSG treatment upregulated the expression levels of antioxidant genes (SOD2 and CAT), anti-apoptotic gene (BCL2), and lipid metabolism-related genes (SCD-1, CD36, PLIN2, FABP3, and FABP4). Taken together, these results suggest that PPARγ plays a vital role in promoting embryonic development by enhancing lipid metabolism and reducing oxidative stress.

During cryopreservation, spermatozoa produce excess reactive oxygen species (ROS), which attack the plasma membrane, disrupt the physiological structure of the sperm, and ultimately decrease semen quality. This study investigated the effects of different N-acetylcysteine (NAC) concentrations on the cryopreservation of semen from Qianbei Ma goats. Semen samples were collected from five bucks with motility rates above 80 %. The treatment groups were diluted 20-fold in extenders containing 3 or 9 mM NAC and cryopreserved in liquid nitrogen, whereas the control group did not include NAC. After thawing, the sperm motility, antioxidant gene expression, enzyme activity, and cell structure were analysed. The NAC-treated groups showed improved post-thaw sperm motility. The 9 mM NAC group presented the highest catalase (CAT) and glutathione peroxidase activities, lowest ROS levels, and fewest apoptotic sperms. Moreover, the 3 mM NAC group presented the highest superoxide dismutase activity and L-cysteine levels and the lowest malondialdehyde levels. Additionally, sperm membrane integrity and mitochondrial membrane potential were significantly higher in the NAC-treated group than that in the control. Further analysis of antioxidant and apoptotic gene expression in the treated sperm revealed that the 9 mM NAC group presented significantly greater CAT and GPX4 expression than the control and 3 mM NAC groups, whereas the apoptotic genes BAX and Caspase3 were elevated in the control group compared to both the NAC groups. In summary, adding NAC to semen extenders enhanced antioxidant gene expression, increased enzyme activity, and improved post-thaw semen quality, with the 9 mM NAC treatment showing the optimal effects.

Pork color is crucial for assessing its safety and freshness, and traditional methods of observing through human eyes are inefficient and subjective. In recent years, several methods have been proposed based on computer vision and deep learning have been proposed, which can provide objective and stable evaluations. However, these methods suffer from a lack of standardized data collection methods and large-scale datasets for training, leading to poor model performance and limited generalization capabilities. Additionally, the model accuracy was limited by an absence of effective image preprocessing of background noises.To address these issues, we have designed a standardized pork image collection device and collected 1707 high-quality pork images. Base on the data, we proposed a novel deep learning model to predict the color. The framework consists of two modules: image preprocessing module and pork color classification module. The image preprocessing module uses the Segment Anything Model (SAM) to extract the pork portion and remove background noise, thereby enhancing the model's accuracy and stability. The pork color classification module uses the ResNet-101 model trained with a patch-based training strategy as the backbone. As a result, the model achieved a classification accuracy of 91.50 % on our high quality dataset and 89.00 % on the external validation dataset. The Porkolor online application is freely available at https://bio-web1.nscc-gz.cn/app/Porkolor.

Fermented sausages are popular meat products with many different varieties. The aroma of fermented sausages depends on the metabolic activities of microbiota, mainly involving lactic acid bacteria and catalase-positive cocci, the group of coagulase-negative staphylococci (CNS) in particular. Regarding staphylococci, this work elucidated their generation of aroma precursors from hydrolase, metabolic activities contributing to aroma development, antioxidant effects that improve aroma via preventing excessive lipid oxidation. The metabolic pathways of staphylococci that play a role in aroma formation involve carbohydrate fermentation, amino acid degradation, fatty acid β-oxidation, and esterase activities. Their antioxidant activities are associated with superoxidase dismutase and catalase activities, as well as the production of antioxidant peptides. Processing conditions may influence CNS communities and affect aroma characteristics of fermented sausages. Implementation of genome sequencing and editing to select and customize CNS with specific biosynthetic metabolic pathways was proposed forward, offering a great potential for enhancing aroma development during sausage fermentation.

Despite the involvement of both immune cells and soluble factors in the etiopathogenesis of cystic ovarian disease (COD), the precise interplay between these components in this reproductive condition remains unclear. Based on this, in the present study we aimed to evaluate the expression of key molecules involved both locally and systemically in the recruitment, infiltration and activation of immune cells in Holstein cows diagnosed with follicular cysts (N = 5). For this, animals from commercial dairy farms located in the milk-productive region of Santa Fe, Argentina were included after their diagnosis were confirmed by ultrasonographic examination and hormonal evaluation. Healthy animals in proestrus, after G6G-Ovsynch hormonal synchronization, were used as controls (N = 5). Protein expression of adhesion molecules, along with mRNA expression of chemokine receptors and cytokines were evaluated. In peripheral blood mononuclear cells, gene expression analysis of inflammatory markers showed that TNF and TGFB1 mRNA expression was significantly lower in COD animals. Also, immunohistochemical analysis revealed that expression of vascular cell adhesion molecule 1 and platelet endothelial cell adhesion molecule was lower in endothelial cells of medullary blood vessels in the COD group. These changes support the hypothesis that alterations in the expression patterns of immune factors, both at systemic and local level, could contribute to the etiopathogenesis of this anovulatory condition.

Over numerous years, breeding herds have faced challenges to sustainability with poor profitability, impact of disease, export market instability, limited labor, and increasing environmental and animal welfare regulations. Many of these scenarios are expected to continue, but their impact lessened with adjustments in management, technology, and business. The prospects for success in the future for the pig industry in various locations are based on costs of pig production efficiency and projections for domestic and export markets. Sow farms are expected to increase in size to meet large retailer needs, while smaller farms will fill domestic regional markets. The risk of PRRS in breeding herds and loss of pigs and infertility will continue to be a major concern for producers. Changes in sow housing will likely continue with designs that meet welfare requirements and allow for practical management of the breeding herd. Trends for selection and increase in litter size will continue but will include measures for birthweight and survival, and traits for heat stress and disease resistance. Changes in boar semen production and AI procedures are unlikely since fertility measures are very high. But advances in technology for identifying fertile and time of ovulation, or procedures that aid in selection of sperm or induction of ovulation, could facilitate reduction in the number of sperm used to produce a litter of pigs.