CK Group Research Articles

Effects of Saccharomyces cerevisiae and Kluyveromyces marxianus on the Physicochemical, Microbial, and Flavor Changes of Sauce Meat during Storage

Saccharomyces cerevisiae (S. cerevisiae) and Kluyveromyces marxianus (K. marxianus) are often used as fermenters in yogurt and alcohol, and have been less studied within meat products. The yeasts were added to sauce meat, and the uninoculated group served as a control in this study to examine and compare the changing patterns of physicochemical and flavor characteristics of S. cerevisiae and K. marxianus on sauce meat during storage. The changes in moisture content, aw, pH, thiobarbituric acid reactive substances (TBARS), and other flavor characteristics were measured in sauce meat during the first, second, fourth, and sixth months after production. The following factors were examined: moisture content, aw, pH, TBARS, peroxide value (POV), acid value (AV), soluble protein (SP), free amino acid (FAA), and volatile flavoring compounds. With VIP > 1 and p < 0.05 as the screening conditions, the partial least squares model (PLS-DA) was used to assess the distinctive flavor components in the sausages. The findings demonstrated that the three groups’ changes in sauce meat were comparable during the first two months of storage but differed significantly between the 4th and 6th months. The moisture content, water activity, and pH of the sauce meat decreased gradually with the storage time; TBARS, AV, and FAA increased significantly; SP decreased significantly from 2.61 to 1.72, while POV increased to 0.03 and then decreased to 0.02. The POV and TBARS values of the yeast-infected meat were substantially lower than those of the control group, and the POV and TBARS values of the meat inoculated with S. cerevisiae were particularly decreased (p < 0.05). The POV and TBARS values of SC (S. cerevisiae group) decreased by 49.09% and 40.15%, respectively, compared to CK (the control group) at the time of storage until June. The experimental group (KM: K. marxianus group) significantly increased the SP and FAA values of the sauce meat (p < 0.05) by 32.4% and 29.84% compared to the CK group, respectively. Esters and olefins as well as alcohols and esters were much greater in meat that had been supplemented with S. cerevisiae and K. marxianus than in meat from the control group. In conclusion, inoculating sauce meat with S. cerevisiae can significantly enhance the quality and flavor of sauce meat while it is being stored.

Exploitation of Post-Ripening Treatment for Improving Cold Tolerance and Storage Period of Jin Huang Mango

The limited cold tolerance of the Jin Huang mango represents a significant impediment to its potential for international trade. Therefore, this study evaluated the quality index changes of green maturity Jin Huang mangoes with different post-ripening treatments and then when stored at different storage periods (7, 14, 21, and 28) at 4 °C followed by 6 days at 20 °C. This study showed that the mangoes treated with 500 ppm ethylene were slow to ripen during 4 °C storage, which could be sustainable even under 20 °C storage. In addition, the control (CK) group failed to mature or ripen unevenly after storage at 4 °C. Moreover, the T3 group (ethylene ripening for 1 day and post-ripening at 20 °C for 1 day) minimized the occurrence of CI during storage compared to the CK group while contributing to a 30% decrease in anthracnose incidence and a decrease in firmness and titratable acid (TA), while total soluble solids (TSS) notably increased, yet the ascorbic acid content in this group was lower. Hence, the treatment conditions of Jin Huang mango using T3 helped extend its shelf-life at 20 °C, stocking and minimizing CI and anthracnose, thereby maintaining a certain quality.

Effects of fermentation with different probiotics on the quality, isoflavone content, and flavor of okara beverages.

The present study aimed to prepare and evaluate a new probiotic functional beverage, using single-probiotic and compound probiotic fermentation on okara. Four different forms of fermentation microorganisms used were Lacticaseibacillus rhamnosus S24 (Lr), Lacticaseibacillus paracasei 6244 (Lp), Lactobacillus acidophilus 11,073 (La), and mixed fermentation (Lr + Lp + La). The physicochemical properties, antioxidant activity, flavor change, and storage period of fermented okara beverages with probiotics were investigated. The results showed that different fermentation schemes could significantly improve the physicochemical properties, antioxidant activity, and sensory quality of the okara beverages. The number of viable bacteria in the Lp group (3.53 × 108 CFU/mL), isoflavone content (0.514 μg/mL) were the highest; total phenol and flavonoid content were 3.32 and 5.68 times higher than in the CK group, respectively. DPPH and ABTS+ free radical scavenging rates were increased by 11.32% and 20%, respectively (p < .05). Through SPME/GC-MS analysis, 44 volatile compounds were identified in the Lr + Lp + La groups, mainly as a result of changes in alcohols and aldehydes produced by fermentation metabolism. It enhances the floral and fruity aroma of the okara beverage. All probiotic-fermented okara beverages can be stored at 4°C for 15 days, with probiotic activity greater than 107 CFU/mL. This study can obtain a probiotic okara beverage rich in soybean isoflavones and with good flavor. Overall, okara can be used to develop functional beverages containing probiotics and contribute to a zero-waste approach in the food industry.

Effect of additive cellulase on fermentation quality of whole-plant corn silage ensiling by a Bacillus inoculant and dynamic microbial community analysis.

Whole-plant corn silage (WPCS) has been widely used as the main roughage for ruminant, which promoted the utilization of corn stover for animal feed production. However, rigid cell wall structure of corn stover limits the fiber digestion and nutrients adsorption of WPCS. This study investigated the effect of adding cellulase on improving the fermentation quality of WPCS ensiling with a Bacillus complex inoculant. With the Bacillus (BA), the lactic acid accumulation in the WPCS was significantly higher than that in control (CK). The additive cellulase (BC) increased the lactic acid content to the highest of 8.2% DW at 60 days, which was significantly higher than that in the CK and BA groups, and it reduced the neutral detergent fiber (NDF) and acid detergent fiber (ADF) contents from 42.5 to 31.7% DW and 28.4 to 20.3% DW, respectively, which were significantly lower than that in the CK and BA groups. The crude protein and starch were not obviously lost. Dynamic microbial community analysis showed that the Bacillus inoculant promoted the lactic acid bacteria (LAB) fermentation, because higher abundance of Lactobacillus as the dominant bacteria was observed in BA group. Although the addition of cellulase slowed the Lactobacillus fermentation, it increased the bacterial community, where potential lignocellulolytic microorganisms and more functional enzymes were observed, thus leading to the significant degradation of NDF and ADF. The results revealed the mechanism behind the degradation of NDF and ADF in corn stover, and also suggested the potential of cellulase for improving the nutritional quality of WPCS.

Lactic Acid Bacteria and Formic Acid Improve Fermentation Quality and Beneficial Predicted Functional Characteristics in Mixed Silage Consisting of Alfalfa and Perennial Ryegrass

The purpose of the present study was to investigate the effect of additives on the fermentation properties of ensiled mixed alfalfa and perennial ryegrass silage in the karst terrain of Southwest China. A mixture of alfalfa and perennial ryegrass was ensiled at a ratio of 3:7 using three experimental treatments: (1) CK (without additives) and distilled water (5 mL kg−1 fresh weight (FW)); (2) FA and formic acid (88%) (5 mL kg−1 FW); and (3) LAB combined with the application of Lactiplantibacillus plantarum and Lentilactobacillus buchneri (2 × 107 cfu/g FW). All samples were packed manually into polyethylene bags, and three polyethylene bags from each treatment were sampled on days 7, 15, and 45. The findings demonstrated that the pH values of all the mixed silages gradually decreased during ensiling. The lactic acid (LA) and acetic acid (AA) contents increased gradually with ensiling time and peaked after 45 days of ensiling. After 45 days of ensiling, the FA and LAB groups effectively preserved the nutrient content of the mixed silage, which presented a reduced neutral detergent fiber and acid detergent fiber content (p &lt; 0.05) and higher water-soluble carbohydrate content (p &lt; 0.05) than the CK group. The fermentation quality of the mixed silages in the FA and LAB groups improved, as indicated by higher (p &lt; 0.05) LA contents and lower (p &lt; 0.05) pH and ammoniacal nitrogen contents after 45 days of ensiling compared to those in the CK group. As fermentation progressed, the abundance of harmful microorganisms (Hafnia obesumbacterium, Enterobacteriaceae, and Sphingomonas) and beneficial microorganisms (Lactiplantibacillus and Lentilactobacillus) decreased and increased, respectively. In addition, compared to those in the CK group, the FA group had higher abundances of “lipid metabolism” and “biosynthesis of antibiotics” and lower abundances of “membrane transport”. Briefly, the results of this study suggest that the incorporation of FA and LAB additives could improve the quality of fermented mixed silage, and that FA is better than LAB. This information is useful for combining forage resources to satisfy the requirements for high-protein feed and for manufacturing ruminant feed annually.

Control location could confuse the evaluation of passivation effect of iron-based biochar and selenium application on wheat grain cadmium accumulation

Inhibiting cadmium (Cd) accumulation in wheat grain could reduce the risk of Cd exposure to human. This study conducted a field experiment and evaluated the effect of iron-based biochar and selenium (Se) application individually or together on Cd accumulation in wheat grains in Cd contaminated soils. Considering the soil Cd heterogeneity in field, we set up 13 replicates of control (CK) and three replicates of each treatment. Results clearly showed that CK location could greatly affect the evaluation whether the difference in the wheat grain Cd concentration between treatments and CK was significant. When we assessed the difference between the treatments (foliar and soil application of Se, iron-based biochar application) and the adjacent CK, there was insignificant difference in the wheat grain Cd concentration between treatment and CK groups. Although soil application of 2 mg kg-1 Se or foliar application of 4 mg L-1 Se significantly increased the grain Se concentration as compared with the adjacent CK, but they still could not reduce the Cd concentrations in wheat grain. However, when we selected the CK that had the highest averaged grain Cd concentration, foliar and soil application of Se could significantly reduce the wheat grain Cd concentration by 47.7% and 41.3-46.1%, respectively. No matter which CK was selected, application of Fe-based biochar had no significant impact on Cd accumulation in wheat grain, and there was insignificant difference in DTPA-Cd concentrations between the iron-based biochar treatment and adjacent control. In conclusion, applying Fe-based biochar and Se in the field could not reduce the Cd accumulation in wheat grain in Cd contaminated weakly alkaline soils.

Effects of exogenous 2,4-epibrassinolide on photosynthetic traits of 53 cowpea varieties under NaCl stress.

This study examined the effects of exogenous 2,4-epibrassinolide (EBR) on photosynthetic traits of 53 cowpea varieties under NaCl stress. The results of different analysis and correlation analysis showed that these 53 germplasm resources had rich genetic diversity, and significant correlations existed among various photosynthetic traits. Under NaCl stress, Pn was highly significantly positively correlated with Gs and Tr and extremely significantly negatively correlated with Ci. Under EBR treatment, Pn was extremely significantly positively correlated with Gs, Ci, Tr and it was significantly negatively correlated with Chla, Chlb, Chl(a + b), and Y(II). Under EBR treatment and NaCl stress, Pn was extremely significantly positively correlated with Tr, and significantly positively correlated with Gs and carotenoid reflectance index. Principal component analysis shows that in CK group and EBR treatment group, cowpea photosynthesis traits can be summarized as six principal components, contributing 82.298 and 83.046%, respectively, can replace 19 photosynthetic traits to evaluate 53 cowpea varieties; under NaCl stress group and EBR + NaCl stress group, photosynthesis traits can be summarized as seven principal components, with cumulative contribution rate of 84.564 and 85.742%, respectively. In the untreated case, the cluster analysis was used to screen 32 cowpea varieties exhibiting the strongest photosynthetic capacity. Under salt stress, six of these varieties were classified as salt-tolerant. Under EBR spraying + salt stress, all four varieties showed strong photosynthetic capacity, and EBR showed the best relief of salt stress. The results of this study will provide a theoretical basis for the application of exogenous EBR to alleviate cowpea salt stress damage.

Study on Detoxification of Biochemical Fulvic Acid on Quasipaa boulengeri Tadpoles under Copper Stress

To understand the detoxification effect of biochemical fulvic acid (BFA) on Quasipaa boulengeri (Q.boulengeri ) tadpoles under copper stress, effects of different concentrations of BFA on growth and physiological indexes of tadpoles. The results showed that the survival rate of tadpoles increased with the increase of BFA concentration. With the increase of BFA concentration, the growth rate of body weight and body length reached the peak at 45 mg/L; The superoxide dismutase(SOD) showed a downward trend in the control group (CK) and an upward trend in each treatment group, with significant difference between the treatment groups (P &lt; 0.05); The content of the malondialdehyde(MDA) and the treatment time and concentration of BFA showed an upward trend in CK group. With the increase of BFA concentration and the content of the MDA decreased, there was significant difference between the treatment groups (P &lt; 0.05). In conclusion, BFA can be used as a detoxification agent under copper stress, and the suitable concentration of BFA is 45 mg/L. This study provides a theoretical basis for the artificial breeding and scientific protection of Q.boulengeri tadpoles.

低压静电场辅助冷藏对草莓贮藏品质的影响

In order to maintain the storage quality of strawberry after harvest and study the effect of low voltage electrostatic field (LVEF)-assisting refrigerated storage on strawberries quality, the study applied the low voltage electrostatic field (3kV 4±1℃ in LVEF group) to store strawberries in refrigeration environment, and setting refrigerated storage at 4±1°C as the control (CK group). The results showed that the freshness days of strawberries refrigerated by low voltage electrostatic field were twice as long as those of refrigerated group. The brightness and red-green degree of strawberries in LVEF group were 1.5 times and 2 times of those in CK group, respectively. The peak hardness of strawberry in LVEF group was 1.43 times of that in CK group, and the hardness decline range was 18.97% lower than that in CK group. The decreasing ranges of Total soluble solids (TSS), Titratable acids (TA) and Vitamin C(VC) in LVEF group were 43.91%, 60.01% and 46.17% lower than those in CK group, respectively. The increment of Malondialdehyde (MDA) of strawberries in LVEF group was 19.77% lower than that in CK group, and the activity peak of Superoxide dismutase (SOD) of strawberries in LVEF group was 1.22 times of that in CK group, and the decreasing range was 22.86% lower than that in CK group. After 10 days of storage, the weight loss rate and decay rate of strawberries in LVEF group and CK group were 16.69%, 15% and 70.65%, 59.45%, respectively. In conclusion, applying low voltage electrostatic field to refrigerated storage can effectively inhibit the quality deterioration of strawberries during refrigerated storage period.

Microecological Shifts in the Rhizosphere of Perennial Large Trees and Seedlings in Continuous Cropping of Poplar.

The cultivation of poplar trees is hindered by persistent cropping challenges, resulting in reduced wood productivity and increased susceptibility to soil-borne diseases. These issues primarily arise from alterations in microbial structure and the infiltration of pathogenic fungi. To investigate the impact on soil fertility, we conducted an analysis using soil samples from both perennial poplar trees and three successive generations of continuously cropped poplar trees. The quantity and community composition of bacteria and fungi in the rhizosphere were assessed using the Illumina MiSeq platform. The objective of this study is to elucidate the impact of continuous cropping challenges on soil fertility and rhizosphere microorganisms in poplar trees, thereby establishing a theoretical foundation for investigating the mechanisms underlying these challenges. The study found that the total bacteria in the BT group is 0.42 times higher than the CK group, and the total fungi is 0.33 times lower than the CK group. The BT and CK groups presented relatively similar bacterial richness and diversity, while the indices showed a significant (p < 0.05) higher fungal richness and diversity in the CK group. The fractions of Bacillus were 2.22% and 2.41% in the BT and CK groups, respectively. There was a 35.29% fraction of Inocybe in the BT group, whereas this was barely observed in the CK group. The fractions of Geopora were 26.25% and 5.99%, respectively in the BT and CK groups. Modifying the microbial community structure in soil subjected to continuous cropping is deemed as the most effective approach to mitigate the challenges associated with this agricultural practice.

γ-Aminobutyric acid enhances salt tolerance by sustaining ion homeostasis in apples

Soil salinization had become a global ecological problem, which restricts the plant growth, and the quantity and quality of fruits. As a signaling molecule, γ-Aminobutyric acid (GABA) mediates a series of physiological processes and stress responses. Our previous research showed that GABA could alleviate drought, low phosphorus, cadmium stresses in apples, but the further research about its physiological mechanisms under salt stress was even more needed. The present study showed that the inhibition of salt stress on plant growth might be effectively alleviated by the treatment of 0.5 mM GABA, and the osmotic balance and photosynthetic capacity of plants could be maintained. Exogenous GABA could effectively inhibit the enrichment of reactive oxygen species and the uptake of Na+, while maintaining ion homeostasis. The experiment results indicated GABA could markedly promote the expression amount of Na+ and K+ transport-related genes (e.g., HKT1, AKT1, NHX1, SOS1, SOS2, and SOS3) in apples under salt stress. Overexpression and interference (RNAi) of MdGAD1 in apple roots, which is a crucial enzyme in the GABA biosynthesis, affected the salt tolerance of plants. Transgenic apple plants with roots of overexpression MdGAD1 showed less relative electrolyte leakage and more expression level of related ion transport genes than CK group, but RNAi MdGAD1 led to the opposite results. These results indicated that GABA accumulation could effectively strengthen the resistance of apple plants to salt stress and alleviate the injury of apple seedlings resulted from salinity.

Effects of exogenous steroid hormones on growth, body color, and gonadal development in the Opsariichthys bidens.

To investigate the effects of exogenous steroid hormones on growth, body color, and gonadal development in the Opsariichthys bidens (O. bidens), synthetic methyltestosterone (MT) and 17β-estradiol (E2) were used for 28 days' treatment of 4-month-old O. bidens before the breeding season. Our results suggested that MT had a significant growth-promoting effect (P < 0.05), whereas E2 played an inhibitory role. On the body surface, the females in the MT group showed gray stripes, and the fish in other groups showed no obvious stripes. The males with MT treatment displayed brighter blue-green stripes compared to the CK and E2 groups. The histological analysis showed that the MT significantly promoted testes development in males, blocked oocyte development, and caused massive apoptosis in females, whereas the E2 group promoted ovarian development and inhibited testes development. Based on qRT-PCR analysis, in females, the expression of igf-1, dmrt1, and cyp19a1a genes revealed that E2 treatment resulted in down-regulation of igf-1 expression and up-regulation of cyp19a1a expression. In males, igf-1 and dmrt1 were significantly up-regulated after MT treatment, and E2 treatment led to down-regulation of igf-1. Therefore, this study demonstrates that MT and E2 play an important role in reversing the morphological sex characteristics of females and males.

The Interaction Effects of Drought–Flood Abrupt Alternation on Rice Yield and Dry Matter Partitioning

The frequent occurrence of drought–flood abrupt alternation (DFAA) seriously affects crop yield. It is particularly important to explore the dynamics of material accumulation and distribution under DFAA stress to analyze the mechanism of yield formation. In this study, a bucket experiment with DFAA stress groups, drought control (DC) groups, flood control (FC) groups, and normal irrigation (CK) groups was set up from the jointing to the heading stage of rice to analyze the interaction effects of DFAA stress on rice yield and dry matter partitioning. The results showed that compared with the CK group, the average yield reduction rate of rice in the DFAA groups was 23.03%, and the number of grains per panicle, total grain number, thousand-seed mass, and seed setting rate decreased. Compared with the DC groups, the DFAA groups had a significant reduction in yield and its components during the flooding period. Compared with the FC groups, the DFAA groups showed a compensation phenomenon in the yield and its components during the drought period. From the end of DFAA stress to the harvest period, the root partitioning index (PI) of the DFAA groups decreased, the stem PI increased first and then decreased, the leaf PI decreased, and the panicle PI increased. The results showed that the rice leaves increased and thickened, and the stems thickened under DFAA conditions to enhance the ability to resist drought and flooding stress, but the panicle rate was reduced, the growth period of rice was delayed, and the redundant growth of stems and leaves was increased. It is suggested that the depth and duration of stagnant water storage during the flood period of DFAA should be controlled, and the transfer and supply of photosynthetic products to grains should be increased to avoid serious yield reductions. The research results provide a theoretical basis for the rational development of farmland DFAA mitigation measures.

Effect of Pu-erh tea pomace on the composition and diversity of cecum microflora in Chahua chicken No. 2

Pu-erh tea pomace (PTP), a solid substance after extracting functional substances or steeping tea, is rich in crude protein, and crude fiber, and could be used as considerable bioactive substances in animal production. However, its application as poultry feed and its role in regulating the characteristics of gut microorganisms is unclear. The present study investigated the effects of PTP on growth performance and gut microbes of chicken. A total of 144 Chahua chickens No. 2 were individually housed and divided into three groups which were fed diets containing 0% (CK), 1% PTP (T1), and 2% PTP (T2), respectively. The serum and cecum contents were collected after slaughter for analysis. The results indicated that growth performance and carcass traits were not affected by the PTP content. Serum total triglyceride (TG), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) levels in the T1 and T2 groups were significantly lower than in the CK group (p &amp;lt; 0.05). The gut microbiota α-diversity in the T2 group was significantly lower than in the CK group (p &amp;lt; 0.05). Based on partial least squares-discriminant analysis (PLS-DA), we observed significant segregation in gut bacterial communities among the groups. At the phylum level, Bacteroidetes and Firmicutes were dominant in the cecum, occupying about 85% of the cecum flora. The relative abundance of Bacteroidetes tended to increase. At the genus level, the relative abundance of Bacteroides is the highest in the CK、T1 and T2 groups. The relative abundances of Bacteroides and Prevotellaceae_UCG-001 microorganisms in the T2 group were significantly higher than in the CK group (p &amp;lt; 0.05). However, the relative abundance of CHKCI001 microorganisms in the T2 group was significantly lower compared to the CK group (p &amp;lt; 0.05). TG content was significantly positively correlated with CHKCI001 relative abundance, and significantly negatively correlated with Prevotellaceae_UCG-001 relative abundance (p &amp;lt; 0.05). Moreover, the LDL-C content was significantly positively correlated with CHKCI001 relative abundance (p &amp;lt; 0.05). In conclusion, PTP could decrease the cholesterol levels in the blood by improving the composition of gut microbiota, which provides a reference for the application of PTP in the poultry industry.

Alternative splicing of the PECTINESTERASE gene encoding a cell wall-degrading enzyme affects postharvest softening in grape

The firmness of table grape berries is a crucial quality parameter. Despite extensive research on postharvest fruit softening, its precise molecular mechanisms remain elusive. To enhance our comprehension of the underlying molecular factors, we initially identified differentially expressed genes (DEGs) by comparing the transcriptomes of folic acid (FA)-treated and water-treated (CK) berries at different time points. We then analyzed the sequences to detect alternatively spliced (AS) genes associated with postharvest softening. A total of 2,559 DEGs were identified and categorized into four subclusters based on their expression patterns, with subcluster-4 genes exhibiting higher expression in the CK group compared with the FA treatment group. There were 1,045 AS-associated genes specific to FA-treated berries and 1,042 in the CK-treated berries, respectively. Gene Ontology (GO) annotation indicated that the AS-associated genes in CK-treated berries were predominantly enriched in cell wall metabolic processes, particularly cell wall degradation processes. Through a comparison between treatment-associated AS genes and subcluster-4 DEGs, we identified eight genes, including Pectinesterase 2 (VvPE2, Vitvi15g00704), which encodes a cell wall-degrading enzyme and was predicted to undergo an A3SS event. The reverse transcription polymerase chain reaction further confirmed the presence of a truncated transcript variant of VvPE2 in the FA-treated berries. Our study provides a comprehensive analysis of AS events in postharvest grape berries using transcriptome sequencing and underscores the pivotal role of VvPE2 during the postharvest storage of grape berries.

A northern snakehead (Channa argus) model of intestinal inflammation induced by Aeromonas hydrophila: Construction and transcriptome analysis

Bacterial intestinal inflammation is a common disease of aquatic animal in high-density aquaculture. This study aims to construct a model of intestinal inflammation in northern snakehead, and analyze the intestinal transcriptome after Aeromonas hydrophila (A. hydrophila) infection by high-throughput sequencing technologies (RNA-seq), in order to obtain candidate genes and regulatory pathways that may participate in inflammatory response. Northern snakehead [(13.05 ± 2.39) g] were infected through anal for 24 h with different concentrations of A. hydrophila (1.0 × 10−4, 1.0 × 10−5, 1.0 × 10−6, 1.0 × 10−7 and 1.0 × 10−8 CFU/mL).Intestinal histology observation showed that infection with A. hydrophila caused obvious inflammatory responses in intestine, especially in hindgut. The results also indicated that intestinal permeability related parameters (D-LA and Na+-K+-ATP), immune-related parameters (C3, LZM, AKP, MPO, IL-1β and TNF-α) and immune-related gene expression (il-1β and tnf-α) were significantly changed compared to the CK group. In this process, high concentration of A. hydrophila infection caused the death of snakehead. On the basis of the above evaluation, we successfully constructed a model of intestinal inflammation induced by A. hydrophila in northern snakehead, and the optimal dosage of A. hydrophila was 1.0 × 10−6 CFU/mL. Subsequently, the constructed model was analyzed on the Illumina Genome Analyser II platform for intestinal transcriptome. Results showed that a total of 370,492,420 clean reads, 145,236 transcripts and 89,431 unigenes were obtained. Moreover, a total of 7566 differentially expressed genes (DEGs) were found, including 4486 upregulated genes and 3080 downregulated genes. Notably, the key pathways [Toll-like receptors (TLRs) and NOD-like receptors (NLRs)] and genes [tlr1, tlr2, tlr5, nf-κb, tnf-α, il-1β, il-10, nod1] related to inflammation were discovered. These results revealed the response of northern snakehead to A. hydrophila at the transcriptional level, which provide insights for the regulatory mechanisms of intestinal inflammation in northern snakehead.

Prickly Ash Seeds improve immunity of Hu sheep by changing the diversity and structure of gut microbiota.

Prickly Ash Seeds (PAS), as a traditional Chinese medicinal herb, have pharmacological effects such as anti-asthma, anti-thrombotic, and anti-bacterial, but their impact on gut microbiota is still unclear. This study used a full-length 16 s rRNA gene sequencing technique to determine the effect of adding PAS to the diet on the structure and distribution of gut microbiota in Hu sheep. All lambs were randomly divided into two groups, the CK group was fed with a basal ration, and the LZS group was given a basal diet with 3% of PAS added to the ration. The levels of inflammatory factors (IL-10, IL-1β, and TNF-α) in intestinal tissues were measured by enzyme-linked immunosorbent assay (ELISA) for Hu sheep in the CK and LZS group. The results indicate that PAS can increase the diversity and richness of gut microbiota, and can affect the community composition of gut microbiota. LEfSe analysis revealed that Verrucomicrobiota, Kiritimatiella, WCHB 41, and uncultured_rumen_bacterium were significantly enriched in the LZS group. KEGG pathway analysis found that LZS was significantly higher than the CK group in the Excretory system, Folding, sorting and degradation, and Immune system pathways (p < 0.05). The results of ELISA assay showed that the level of IL-10 was significantly higher in the LZS group than in the CK group (p < 0.05), and the levels of TNF-α and IL-1β were significantly higher in the CK group than in the LZS group (p < 0.05). LEfSe analysis revealed that the dominant flora in the large intestine segment changed from Bacteroidota and Gammaproteobacteria to Akkermansiaceae and Verrucomicrobiae after PAS addition to Hu sheep lambs; the dominant flora in the small intestine segment changed from Lactobacillales and Aeriscardovia to Kiritimatiellae and WCHB1 41. In conclusion, the addition of PAS to sheep diets can increase the number and types of beneficial bacteria in the intestinal tract, improve lamb immunity, and reduce intestinal inflammation. It provides new insights into healthy sheep production.

Influence of copper and aging on freely dissolved tetracycline concentration in soil.

Copper (Cu) and tetracyclines (TCs) often coexist in agricultural soils because of the use of manures on farmland; however, the influence of Cu on the bioavailability of TCs is still unclear, especially for cases with aging Cu. The freely dissolved concentrations (FDCs) of TCs are believed to be directly related to their bioavailability. In the present study, the FDCs of TCs were determined using organic-diffusive gradients in thin films (o-DGT), and the influence of Cu on the FDCs of TCs in soils was evaluated. The results showed that the FDCs of tetracycline (TC), oxytetracycline (OTC), and chlortetracycline (CTC) were 0.11-0.93, 0.28-1.02, and 0.24-0.53 μg/kg in the CK groups (no Cu added) and accounted for 0.09-0.58, 0.10-1.40, and 0.05-1.19‰ of their total concentrations which ranged from 0.2 to 10.0 mg/kg for TC, OTC, and CTC, respectively. The co-contamination of Cu reduced the FDCs of TCs in most cases, and aging increased the influence of Cu. The presence of Cu resulted in a decrease in the TC FDC by 35.48-95.04% in aged soils and 3.42-87.19% in newly prepared soils. FTIR analysis revealed that aging facilitated the bonding of Cu to soil particles via Cu-O, and Cu bonded to groups such as hydroxyl groups (-OH) in TCs. Our results suggested that the presence of Cu might reduce the bioavailability of TCs, and aging would enhance these effects. This is helpful for the bioavailability analysis of TCs under co-contamination of heavy metals.

Effects of dietary chito-oligosaccharide and β-glucan on the water quality and gut microbiota, intestinal morphology, immune response, and meat quality of Chinese soft-shell turtle (Pelodiscus sinensis).

Chito-oligosaccharides (COS) and β-glucan are gradually being applied in aquaculture as antioxidants and immunomodulators. However, this study examined the effects of dietary supplementation of COS and β-glucan on the water quality, gut microbiota, intestinal morphology, non-specific immunity, and meat quality of Chinese soft-shell turtle. To investigate the possible mechanisms, 3-year-old turtles were fed basal diet (CK group) and 0.1%, 0.5%, and 1% COS or β-glucan supplemented diet for 4 weeks. Colon, liver, blood and muscle tissues, colon contents, water and sediment of paddy field samples were collected and analyzed after feeding 2 and 4 weeks. The results indicated that COS and β-glucan altered microbial community composition and diversity in Chinese soft-shell turtles. The relative abundance of Cellulosilyticum, Helicobacter and Solibacillus were increased after feeding COS, while Romboutsia, Akkermansia and Paraclostridium were increased after feeding β-glucan, whereas Cetobacterium, Vibrio and Edwardsiella were enriched in the control group. Furthermore, colon morphology analysis revealed that COS and β-glucan improved the length and number of intestinal villi, and the effect of 0.5% β-glucan was more obvious. Both β-glucan and COS significantly improved liver and serum lysozyme activity and antibacterial capacity. COS significantly increased the total antioxidant capacity in the liver. Further, 0.1% β-glucan significantly increased the activity of hepatic alkaline phosphatase, which closely related to the bacteria involved in lipid metabolism. Moreover, dietary supplementation with 1% COS and 1% β-glucan significantly enhanced the content of total amino acids, especially umami amino acids, in muscle tissue, with β-glucan exerting a stronger effect than COS. Additionally, these two prebiotics promoted the quality of culture water in paddy fields and reshaped the bacterial community composition of aquaculture environment. All these phenotypic changes were closely associated with the gut microbes regulated by these two prebiotics. In summary, the findings suggest that dietary supplementation with COS and β-glucan in Pelodiscus sinensis could modulate the gut microbiota, improve intestinal morphology, enhance non-specific immunity and antioxidant capacity of liver and serum, increase meat quality, and improve the culture water environment. This study provides new insights and a comprehensive understanding of the positive effects of COS and β-glucan on Pelodiscus sinensis.

Effects of Enrofloxacin and Ciprofloxacin on Growth and Toxin Production of Microcystis aeruginosa

Microcystis aeruginosa is a common cyanobacterium found in water blooms and often causes ecological harm. Antibiotics are also increasingly used for the prevention and treatment of bacterial infections in aquaculture. However, since most antibiotics cannot be fully metabolized, they enter the water environment and cause ecological impacts. In this paper, the effects of the two fluoroquinolone antibiotics (enrofloxacin and ciprofloxacin) on the population density and microcystins (MCs) production of M. aeruginosa were studied. It is of great significance for the ecological risk assessment of antibiotics in the water environment. The results showed that the 96h EC50 values of enrofloxacin and ciprofloxacin to M. aeruginosa were 56.10 mg/L and 49.80 mg/L, respectively, and the toxicity of ciprofloxacin to M. aeruginosa was slightly stronger than that of enrofloxacin. With the increase in the two antibiotic concentration, the growth inhibition rate (IR) increased, but when the concentration reached a certain level, the IR would reach its threshold. Long-term exposure to low concentrations of these two antibiotics is not only more likely to lead to the outbreak of M. aeruginosa, but also increase its toxin production capacity. The highest contents of MCs in enrofloxacin and ciprofloxacin groups were 95.539 μg/g and 93.720 μg/g, respectively. The MCs value of these three enrofloxacin treatment groups was more than above 51.8 times that of control group (CK) on the 4th day; from 8th day to 14th day, the MCs value of these three enrofloxacin treatment groups was more than above 3.2 times that of CK group. For ciprofloxacin, the MCs value of the treatment group was more than 64.98 times that of the CK group on the 4th day, and from 8th day to 14th day, the MCs value of the treatment group was more than 2.7 times that of the CK group. These findings provide crucial management rationale.