Neglected function of gastrin to reduce feeding in Siberian sturgeon (Acipenser baerii) via cholecystokinin receptor B.

Gastrin is an important intragastrointestinal hormone, but reports on its regulation of feeding behavior in fish are still scarce. This study aimed to determine the feeding regulatory function of gastrin in sturgeon. In this study, a gastrin/cholecystokinin-like peptide was identified in the genomes of sturgeon and proved to be gastrin by evolutionary tree analysis. Tissue distribution of gastrin and its receptor, cholecystokinin receptor B (CCKRB), showed that both had high mRNA abundance in the hypothalamus and gastrointestinal tract. In the duodenum, gastrin and CCKRB mRNAs were reduced at 1 h of fasting, and both were also observed in the stomach and hypothalamus in response to changes in feeding status. Sulfated gastrin 17 is the major form of gastrin in vivo. Therefore, we investigated the effect of sulfated gastrin 17 on feeding by intraperitoneal injection into Siberian sturgeon using sulfated gastrin 17. The results showed that gastrin 17 significantly reduced the cumulative feeding of Siberian sturgeon in the short term (1, 3 and 6 h) and long term (1, 2, 3, 4, 5 and 7 days). Finally, we explored the potential mechanism of feeding inhibition after intraperitoneal injection of gastrin 17 for 7 consecutive days. The results showed that gastrin 17 treatment significantly increased the mRNA levels of anorexigenic peptides (cart, cck and pyy), while it had no significant effect on the mRNA abundance of orexigenic peptides (npy and agrp). In addition, gastrin 17 treatment significantly affected the expression of appetite signaling pathways in the hypothalamus, such that the mRNA expression of ampkα1 was significantly reduced, whereas the mRNA abundance of stat3, mtor and s6k was significantly increased. In conclusion, the present study confirmed the anorectic effect of gastrin on Siberian sturgeon.

Enhanced organic degradation and microbial community cooperation by inoculating Bacillus licheniformis in low temperature composting.

Microbial activity and interaction are the important driving factors in the start-up phase of food waste composting at low temperature. The aim of this study was to explore the effect of inoculating Bacillus licheniformis on the degradation of organic components and the potential microbe-driven mechanism from the aspects of organic matter degradation, enzyme activity, microbial community interaction, and microbial metabolic function. The results showed that after inoculating B. licheniformis, temperature increased to 47.8°C on day 2, and the degradation of readily degraded carbohydrates (RDC) increased by 31.2%, and the bioheat production increased by 16.5%. There was an obvious enhancement of extracellular enzymes activities after inoculation, especially amylase activity, which increased by 7.68 times on day 4. The inoculated B. licheniformis colonized in composting as key genus in the start-up phase. Modular network analysis and Mantel test indicated that inoculation drove the cooperation between microbial network modules who were responsible for various organic components (RDC, lipid, protein, and lignocellulose) degradation in the start-up phase. Metabolic function prediction suggested that carbohydrate metabolisms including starch and sucrose metabolism, glycolysis / gluconeogenesis, pyruvate metabolism, etc., were improved by increasing the abundance of related functional genes after inoculation. In conclusion, inoculating B. licheniformis accelerated organic degradation by driving the cooperation between microbial network modules and enhancing microbial metabolism in the start-up phase of composting.

Bacillus licheniformis inoculation promoted humification process for kitchen waste composting: Organic components transformation and bacterial metabolic mechanism.

Kitchen waste (KW) composting always has trouble with slow humification process and low humification degree. The objective of this study was to develop potentially efficient solutions to improve the humification of KW composting, accelerate the humus synthesis and produce HS with a high polymerization degree. The impact of Bacillus licheniformis inoculation on the transformation of organic components, humus synthesis, and bacterial metabolic pathways in kitchen waste composting, was investigated. Results revealed that microbial inoculation promoted the degradation of organic constituents, especially readily degradable carbohydrates during the heating phase and lignocellulose fractions during the cooling phase. Inoculation facilitated the production and conversion of polyphenol, reducing sugar, and amino acids, leading to an increase of 20% in the content of humic acid compared to the control. High-throughput sequencing and network analysis indicated inoculation enriched the presence of Bacillus, Lactobacillus, and Streptomyces during the heating phase, while suppressing the abundance of Pseudomonas and Oceanobacillus, enhancing positive microbial interactions. PICRUSt2 analysis suggested inoculation enhanced the metabolism of carbohydrates and amino acids, promoting the polyphenol humification pathway and facilitating the formation of humus. These findings provide insights for optimizing the humification process of kitchen waste composting by microbial inoculation.

Hepatic Steatosis: CT-Based Prevalence in Adults in China and the United States and Associations With Age, Sex, and Body Mass Index.

BACKGROUND. Calibrated CT fat fraction (FFCT) measurements derived from un-enhanced abdominal CT reliably reflect liver fat content, allowing large-scale population-level investigations of steatosis prevalence and associations. OBJECTIVE. The purpose of this study was to compare the prevalence of hepatic steatosis, as assessed by calibrated CT measurements, between population-based Chinese and U.S. cohorts, and to investigate in these populations the relationship of steatosis with age, sex, and body mass index (BMI). METHODS. This retrospective study included 3176 adults (1985 women and 1191 men) from seven Chinese provinces and 8748 adults (4834 women and 3914 men) from a single U.S. medical center, all drawn from previous studies. All participants were at least 40 years old and had undergone unenhanced abdominal CT in previous studies. Liver fat content measurements on CT were cross-calibrated to MRI proton density fat fraction measurements using phantoms and expressed as adjusted FFCT measurements. Mild, moderate, and severe steatosis were defined as adjusted FFCT of 5.0-14.9%, 15.0-24.9%, and 25.0% or more, respectively. The two cohorts were compared. RESULTS. In the Chinese and U.S. cohorts, the median adjusted FFCT for women was 4.7% and 4.8%, respectively, and that for men was 5.8% and 6.2%, respectively. In the Chinese and U.S. cohorts, steatosis prevalence for women was 46.3% and 48.7%, respectively, whereas that for men was 58.9% and 61.9%, respectively. Severe steatosis prevalence was 0.9% and 1.8% for women and 0.2% and 2.6% for men in the Chinese and U.S. cohorts, respectively. Adjusted FFCT did not vary across age decades among women or men in the Chinese cohort, although it increased across age decades among women and men in the U.S. cohort. Adjusted FFCT and BMI exhibited weak correlation (r = 0.312-0.431). Among participants with normal BMI, 36.8% and 38.5% of those in the Chinese and U.S. cohorts, respectively, had mild steatosis, and 3.0% and 1.5% of those in the Chinese and U.S. cohorts, respectively, had moderate or severe steatosis. Among U.S. participants with a BMI of 40.0 or greater, 17.7% had normal liver content. CONCLUSION. Steatosis and severe steatosis had higher prevalence in the U.S. cohort than in the Chinese cohort in both women and men. BMI did not reliably predict steatosis. CLINICAL IMPACT. The findings provide new information on the dependence of hepatic steatosis on age, sex, and BMI.

Identification, tissue distribution, and anorexigenic effect of amylin in Siberian sturgeon (Acipenser baeri).

Amylin is a 37-amino acid polypeptide that has been found to be involved in feeding regulation in some mammals, birds, and goldfish. We cloned amylin of Siberian sturgeon and detected its distribution pattern in 15 tissues. The expression levels in the periprandial period (pre-and post-feeding), the changes in the food intake, and the expression levels of related appetite factors after the intraperitoneal injection of amylin were detected. The expression of amylin was found to be the highest in the hypothalamus. Compared with 1 h pre-feeding, the expression levels of amylin in the hypothalamus and duodenum were increased significantly 1 h post-feeding. Compared with the control group (saline), intraperitoneal injection of 50 ng/g, 100 ng/g, and 200 ng/g of amylin significantly inhibited food intake at 1 h post injection, but not at 3 h and 6 h. The injection of 50 ng/g, 100 ng/g, and 200 ng/g amylin significantly inhibited the cumulative feed. After 1 h of 50 ng/g amylin injection, the levels of MC4R and somatostatin in the hypothalamus increased significantly, while the levels of amylin and NPY decreased significantly. The levels of CCK in the valvular intestine were increased significantly. Insulin in the duodenum was also increased significantly, but there was no significant change in ghrelin in the duodenum. These results show that amylin inhibits feeding in Siberian sturgeon by down-regulating the appetite-stimulating factor NPY and up-regulating the appetite-suppressing factors somatostatin, MC4R, CCK, and insulin. This study provides a theoretical basis for studying the feeding function and action mechanisms of amylin in Siberian sturgeon.

Cloning and expression of kiss genes and regulation of feeding in Siberian sturgeon (Acipenser baerii).

In 1996, kiss was reported to regulate feeding in mammals, but studies are limited in fish. Our study aimed to explore the possible role of kiss in the regulation of feeding in Siberian sturgeon (Acipenser baerii). kiss1 and kiss2 were cloned, and the expression patterns were analyzed in Siberian sturgeon. The complete coding regions of kiss1 and kiss2 genes were 393 and 471 bp. Both kiss1 and kiss2 showed the highest expression level in the hypothalamus. During the periprandial and fasting experiments, the expression of kiss1 and kiss2 highly significantly increased in the hypothalamus after feeding (P < 0.01). Compared with the feeding group, in hypothalamus, kiss1 expression in the fasting group highly significantly decreased (P < 0.01). In contrast, kiss2 expression had no significant difference on days 1 and 7 (P > 0.05) but highly significantly increased on day 14 (P < 0.01). Subsequently, the feeding function was verified by intraperitoneal (i.p.) injection of Kp1(10) and Kp1(10) into fish. The results showed that i.p. injection of 1 µg/g BW Kp1(10) or 0.01 µg/g BW Kp2(10) could significantly reduce 0-1 h food intake (P < 0.05) and affected the expression levels of apelin, ghrelin, leptin, nmu, etc. in the hypothalamus. These results suggested that kiss1 plays an anorexic role in both short- and long-term feeding regulation, while kiss2 plays a short-term anorexic and long-term orexigenic role. This study described kiss as a novel regulator of appetite in fish and laid the groundwork for further studies focused on physiological function. HIGHLIGHTS: • The kiss1 and kiss2 of Siberian sturgeon were cloned. • The expression levels of kiss1 and kiss2 mRNA were the highest in the hypothalamus. • Postprandial hypothalamic kiss1 and kiss2 expression levels increased in the periprandial experiment. • In the fasting test, the expression of hypothalamic kiss1 decreased after fasting, while the expression of kiss2 increased after fasting on the 14th day. • Siberian sturgeon food intake was reduced, and appetite factors expression levels in the hypothalamus were altered after intraperitoneal injection of Kp1(10) and Kp2(10).

Characterization, tissue distribution of resistin gene and the effect of fasting and refeeding on resistin mRNA expression in Siberian sturgeon (Acipenser baerii).

Resistin as an adipokine identified from rodents in 2001 is involved in many biological processes. However, little is known about this gene in fish. We cloned Siberian sturgeon (Acipenser baerii) resistin cDNA of 795 base pairs, encoding 107 amino acids, which showed 38-40% identity to human and rodents. Real-time quantitative PCR showed that the resistin gene was widely distributed in tissues of Siberian sturgeon, with the highest expression in liver. After fasting for 1, 3, 6 and 10 days, the expression of the resistin gene in the liver of Siberian sturgeon decreased significantly, and after refeeding on the 10 days of fasting the resistin mRNA expression increased rapidly, suggesting that resistin may play an important role in liver in response to starvation. Taken together, these results suggest that resistin may be involved in the regulation of energy homeostasis in liver.

Identification, tissue distribution, periprandial expression, and anorexigenic effect of spexin in Siberian sturgeon, Acipenser baeri.

Spexin (Spx), an endogenous peptide, is considered to be a neuropeptide. In a few fish and mammals, it has been proved to play a role in the regulation of animal feeding. However, the possible mechanisms of spexin regulating food intake are mostly blurry in vertebrates including Siberian sturgeon. In this study, firstly, the coding sequence of spexin cDNA was cloned and sequenced in Siberian sturgeon. Then, we detected that spexin mRNA was widely expressed in the hypothalamus, gastrointestinal tract, and liver, with the highest expression in the hypothalamus. The expression of spexin mRNA in the hypothalamus was significantly increased after food intake. At 1 h, 3 h, and 6 h after injection, the food intake in the spexin group (0.10, 0.30, and 0.90 µg/g BW) was significantly lower than that in the saline group. Moreover, compared with the saline group, the mRNA expression of anorectic nucb2, cart, ucn3, and pyy in the hypothalamus was significantly upregulated and orectic npy was significantly downregulated at 1 h after spexin injection; in the stomach, the mRNA expression of nucb2 and pyy was significantly upregulated. All in all, these results provide evidence for the anorexic effect of spexin on Siberian sturgeon.

Transcriptome analysis and the effects of polyunsaturated fatty acids on the immune responses of the critically endangered angtze sturgeon (Acipenser dabryanus).

The poor understanding of nutrition needed has become a significant obstruction to artificial conservation of Yangtze sturgeon (Acipenser dabryanus) and the relationship between ployunsaturated fatty acid nutrition and the immune response of Yangtze sturgeon is remains unclear. To explore this relationship, the immune response was determined by the activities of serum immune-related enzymes and the transcriptome pattern in the spleen after feeding different fat source diets for 7 weeks. In addition, the gene expression pattern after a lipopolysaccharide (LPS) challenge was investigated in the presence of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). Long-term feeding of the fish oil diets increased the serum immune-related enzyme activities, including lysozyme, acid phosphatase, and alkaline phosphatase of Yangtze sturgeon. More than 653,999 transcripts with an N50 length of 1047 bp were obtained and a final set of 280,408 unigenes was generated. After annotating the unigenes, 3549 genes were assigned to the immune system and 2839 were identified to participate in the response to the different fat sources. A transcriptome assay showed the fish oil diets moderately upregulated immune-related signaling pathways in the spleen of Yangtze sturgeon, including NLR signaling, platelet activation, Fc gamma R-mediated phagocytosis, Th17 cell differentiation, and Th1 and Th2 cell differentiation. The quantitative polymerase chain reaction (qPCR) results of candidate genes for these pathways showed similar results. The LPS challenge study revealed that DHA and EPA moderately upregulated the candidate immune-related genes and modulated excessive activation of the immune pathway by the pathogen. This study confirmed the immunomodulatory function of unsaturated fatty acids in Yangtze sturgeon. This research will provide a reference for the preparation of artificial diets for Yangtze sturgeon.

The transcripts of CRF and CRF receptors under fasting stress in Dabry's sturgeon (Acipenser dabryanus Dumeril).

Dabry's sturgeon (Acipenser dabryanus Dumeril, 1868) belongs to Sturgeon and is distributed throughout the mainstream of the upper Yangtze River. While there is little research onphysiological mechanism of Dabry's sturgeon, such as feeding regulation by the CRF system. At present, CRF is thought to regulate feeding via CRF receptors (CRF-Rs) in several mammals, but relatively few studies of CRF and feeding exist in teleosts. Herein, the transcripts of CRF and CRF-Rs under fasting stress in Dabry's sturgeon (Acipenser dabryanus Dumeril) have been explored. A full length Dabry's sturgeon CRF cDNA of 953 bp was identified, which contained a 447 bp open reading frame (ORF). A partial CRF-R1 cDNA of 1053 bp and CRF-R2 cDNA of 906 bp corresponding to the coding sequences (CDS) was obtained. In addition, analysis of the tissue distribution of CRF and CRF-Rs mRNAs revealed they were widely distributed in the central and peripheral nervous systems. Furthermore, periprandial (preprandial and postprandial), fasting, and re-feeding experiments revealed CRF mRNA was significantly increased 1 h and 3 h after feeding and CRF and CRF-Rs transcripts were significantly decreased after 10 days fasting, and significantly increased on re-feeding on day 10. These results suggest that CRF and CRF-Rs might regulate feeding by acting as satiety factors.

UCN3 suppresses food intake in coordination with CCK and the CCK2R in Siberian sturgeon (Acipenser baerii).

Urocortin-3 (UCN3) as a brain-gut peptide inhibits food intake of animal, but the underlying mechanism is not clear. To explore the appetite mechanism about the action of UCN3 in fish, intraperitoneal injection of UCN3 with CCK8, Lorglumide (CCK1R antagonist) or LY225910 (CCK2R antagonist) were conducted. Siberian sturgeon administrated with UCN3 and CCK8 showed a drastic reduction in food intake. The anorectic effect of UCN3 was significantly blocked by LY225910, but not affected by Lorglumide. Furthermore, LY225910 could effectively reverse appetite factor mRNA expressions, including cck, pyy, cart, npy, ucn3, apelin and nucb2 in the whole brain, stomach and intestinum valvula, but Lorglumide could only partially reverse these effects, suggesting the anorectic effect of UCN3 may be primarily mediated CCK2R in Siberian sturgeon. This study indicates for the first time in fish that UCN3 may inhibit food intake in coordination with CCK and CCK2R.

Motilin, a Novel Orexigenic Factor, Involved in Feeding Regulation in Yangtze Sturgeon (Acipenser dabryanus).

Motilin is a gastrointestinal hormone that is mainly produced in the duodenum of mammals, and it is responsible for regulating appetite. However, the role and expression of motilin are poorly understood during starvation and the weaning stage, which is of great importance in the seeding cultivation of fish. In this study, the sequences of Yangtze sturgeon (Acipenser dabryanus Motilin (AdMotilin)) motilin receptor (AdMotilinR) were cloned and characterized. The results of tissue expression showed that by contrast with mammals, AdMotilin mRNA was richly expressed in the brain, whereas AdMotilinR was highly expressed in the stomach, duodenum, and brain. Weaning from a natural diet of T. Limnodrilus to commercial feed significantly promoted the expression of AdMotilin in the brain during the period from day 1 to day 10, and after re-feeding with T. Limnodrilus the change in expression of AdMotilin was partially reversed. Similarly, it was revealed that fasting increased the expression of AdMotilin in the brain (3 h, 6 h) and duodenum (3 h), and the expression of AdMotilinR in the brain (1 h) in a time-dependent manner. Furthermore, it was observed that peripheral injection of motilin-NH2 increased food intake and the filling index of the digestive tract in the Yangtze sturgeon, which was accompanied by the changes of AdMotilinR and appetite factors expression in the brain (POMC, CART, AGRP, NPY and CCK) and stomach (CCK). These results indicate that motilin acts as an indicator of nutritional status, and also serves as a novel orexigenic factor that stimulates food intake in Acipenser dabryanus. This study lays a strong foundation for the application of motilin as a biomarker in the estimation of hunger in juvenile Acipenser dabryanu during the weaning phase, and enhances the understanding of the role of motilin as a novel regulator of feeding in fish.

Identification of oxidative phosphorylation-related genes in moyamoya disease by combining bulk RNA-sequencing analysis and machine learning.

Introduction: Moyamoya disease (MMD) is a chronic cerebrovascular disease that can lead to ischemia and hemorrhagic stroke. The relationship between oxidative phosphorylation (OXPHOS) and MMD pathogenesis remains unknown. Methods: The gene expression data of 60 participants were acquired from three Gene Expression Omnibus (GEO) datasets, including 36 and 24 in the MMD and control groups. Differentially expressed genes (DEGs) between MMD patients MMD and control groups were identified. Machine learning was used to select the key OXPHOS-related genes associated with MMD from the intersection of DEGs and OXPHOS-related gene sets. Gene ontology (GO), Kyoto encyclopedia of genes and genomes (KEGG), gene set enrichment analysis (GSEA), Immune infiltration and microenvironments analysis were used to analyze the function of key genes. Machine learning selected four key OXPHOS-related genes associated with MMD: CSK, NARS2, PTPN6 and SMAD2 (PTPN6 was upregulated and the other three were downregulated). Results: Functional enrichment analysis showed that these genes were mainly enriched in the Notch signaling pathway, GAP junction, and RNA degradation, which are related to several biological processes, including angiogenesis, proliferation of vascular smooth muscle and endothelial cells, and cytoskeleton regulation. Immune analysis revealed immune infiltration and microenvironment in these MMD samples and their relationships with four key OXPHOS-related genes. APC co-inhibition (p = 0.032), HLA (p = 0.001), MHC I (p = 0.013), T cellco- inhibition (p = 0.032) and Type I IFN responses (p < 0.001) were significantly higher in the MMD groups than those in the control groups. The CSK positively correlated with APC co-inhibition and T cell-co-inhibition. The NARS2 negatively correlated with Type I IFN response. The SMAD2 negatively correlated with APC co-inhibition and Type I IFN response. The PTPN6 positively correlated with HLA, MHC I and Type I IFN responses. Discussion: This study provides a comprehensive understanding of the role of OXPHOS in MMD and will contribute to the development of new treatment methods and exploration of MMD pathogenesis.

The contribution of microbial necromass to soil organic carbon and influencing factors along a variation of habitats in alpine ecosystems.

A growing consensus is reached that microbes contributes to regulating the formation and accumulation of soil organic carbon (SOC). Nevertheless, less is known about the role of soil microbes (necromass, biomass) in SOC accumulation in different habitat conditions in alpine ecosystems. To address this knowledge gap, the composition and distribution of amino sugars (ASs) and phospholipid fatty acids (PLFAs) as biomarkers of microbial necromass and biomass were investigated in forest, meadow and wetland soil profile (0-40 cm) of Mount Segrila, Tibet, China, as well the contribution of bacterial and fungal necromass to SOC. The results revealed that microbial necromass carbon contributed 45.15 %, 72.51 % and 78.08 % on average to SOC in 0-40 cm forest, meadow and wetland soils, respectively, and decreased with microbial biomass. Fungal necromass contributed more to SOC in these habitats than bacterial necromass. Microbial necromass increased with microbial biomass and both of them decreased with soil depth in all habitats. The necromass accumulation coefficient was significantly correlated with microbial necromass and biomass, affected by habitat and soil moisture. Structural equation model indicated that soil abiotic factors indirectly mediated the accumulation of SOC through microbial necromass and biomass. This study revealed that different habitats and soil depths control considerably soil physicochemical properties and microbial community, finally influencing SOC accumulation in alpine ecosystems, which emphasized the influence of abiotic factors on microbial necromass and biomass for SOC accumulation in alpine ecosystems.

Carbon-containing additives changes the phosphorus flow by affecting humification and bacterial community during composting.

Phosphorus recycling from organic wastes to prepare a fertilizer by composting is promising. The aim of this study was to compare the effect of diverse carbon-containing additives (T1, glucose; T2, biochar; T3, woody peat) on phosphorus (P) fractions transformations, humus formation and bacterial community succession in chicken manure composting. Results showed that orthophosphate monoester was significantly related to the humification process, and glucose or woody peat addition increased the P in humus. Lentibacillus was a key carbon cycle bacteria related to organics stabilization affected by carbon-containing additives. Redundancy analysis and variation partitioning indicated that phosphatase enzyme activity driven by bacterial community and humic substance had 59.7% contribution to P fractions dynamics. The findings highlight an efficient humus-regulation P stabilization way, notably in composting adding glucose to form humus with a better binding ability to labile P forms and phosphatase.

Effects of chemical additives and mature compost on reducing nitrogen loss during food waste composting.

This study is aimed at adding different types of mature compost and sulfur powder, as additives into food waste composting to investigate the effect on nitrogen loss and compost maturity. The composting experiment used the in-vessel composting method and was conducted continuously for 15 days. High-throughput sequencing was used to analyze the bacterial community during composting. Results showed that the secondary fermentation mature compost mixed with sulfur powder group had the most reduction of ammonia emission (56%) and the primary fermentation mature compost amendments were the most effective for nitrous oxide emission reduction (37%). The temperature, pH, and nitrogen forms of transformation of the pile significantly affect the nitrogen loss during composting. Firmicutes helped to promote the rapid warming of the pile, and Actinobacteria and Proteobacteria played an important role in decomposition of organic matter. Thermobifida and Ureibacillus had a main contribution to the rapid degradation of organic matter in the process of composting. The relative abundance of nitrogen-fixing bacteria was higher, and the relative abundance of predominantly ammonifying and denitrifying bacteria was lower than the control group, with the addition of different additives.

Suppressive performance of food waste composting with polylactic acid: Emphasis on microbial core metabolism pathways and mechanism.

The aim of this study was to assess the effect of polylactic acid (PLA) on microbial community composition and core metabolism pathways in food waste (FW) composting. The presence of PLA negatively influenced microbial community richness and decreased respectively the abundance of Bacillus, Halocella and Cellvibrio at mesophilic, thermophilic and mature phases. Analysis of microbial metabolism at the gene level help to understand the mechanism in co-composting with FW and PLA. The expression of core functional genes related to lactide metabolism was stimulated by PLA degradation at thermophilic and mature phases. The sum of absolute abundance of functional genes that involved in first and second carbon oxidation of tricarboxylic acid cycle was decreased due to the existence of PLA. The transformation between 2-Oxoglutarate and Succinyl-CoA were interfered in thermophilic phase, which might result in the lower germination index in PLA group (115%) than that in control (186%).

Phosphorus transformation behavior and phosphorus cycling genes expression in food waste composting with hydroxyapatite enhanced by phosphate-solubilizing bacteria.

This study aimed to explore the effect of phosphate-solubilizing bacteria (PSB) Bacillus inoculation in the cooling stage on hydroxyapatite dissolution, phosphorus (P) forms transformation, and bacterial P cycling genes in food waste composting with hydroxyapatite. Results indicated that PSB inoculation promoted the dissolution of hydroxyapatite, increased P availability of compost by 8.1% and decreased the ratio of organic P to inorganic P by 10.2% based on sequential fractionation and 31P nuclear magnetic resonance spectroscopy. Illumina sequencing indicated Bacillus relative abundance after inoculation increased up to one time higher than control after the cooling stage. Network analysis and metabolic function of bacterial community analysis suggested inorganic P solubilizing genes of Bacillus and organic P mineralization genes of other genera were improved after inoculation in the core module. Therefore, bioaugmentation of PSB in the cooling stage may be a potential way to improve P bioavailability of bone and food waste in composting.

Role of fungal communities and their interaction with bacterial communities on carbon and nitrogen component transformation in composting with different phosphate additives.

The aim of the study was to compare the succession of fungal community and their interaction with bacterial community during pig manure composting with different phosphate additives and further to identify microbial roles on the transformation of carbon and nitrogen (C&N) components and compost maturity. The results showed that the composition of fungal community was significantly affected by pH in composting and acidic phosphate might postpone the C&N degradation process. Network analysis showed that phosphate additives, especially acidic additives, could increase the interaction of microbial community but acidic phosphate decreased the core fungi:bacteria ratio. Redundancy analysis indicated that the interactions between bacterial and fungal communities played more roles than individual contribution of bacteria or fungi for C&N conversion of composting. Structural equation modeling suggested that bacterial community was positively directly correlated to C&N loss and the participation of fungal community significantly benefited the maturity of composting. pH exhibited a great intermediated role for driving C&N conversion, maturity, and safety of composts by regulating bacterial and fungal community in composting with phosphate addition, which suggested a fast-composting way based on pH regulation by additives.

Comparing the bacterial composition, succession and assembly patterns in plastisphere and kitchen waste composting with PLA/PBAT blends.

Biodegradable plastics has aroused increasing concern due to the negative environmental impact of plastic waste, however, the impact of biodegradable plastics mixed into kitchen waste (KW) on composting remains poorly understood, especially focusing on bacterial communities in the unique "plastisphere". Here, KW composting for 120 days with adding poly lactic acid / poly butylene adipate-co-terephthalate (PLA/PBAT) plastics were conducted to reveal the dynamics of bacterial composition, succession, and assembly process in different ecological niches (compost and plastisphere). Results showed that the existence of PLA/PBAT plastics in composting would not significantly affect the safety and maturation of composts. After composting, 80% PLA/PBAT were degraded and there were prominent divergences of bacterial compositions between plastisphere, composts with PLA/PBAT and control. Co-occurrence network suggested that PLA/PBAT plastisphere exhibited higher network complexity and cohesion than that in compost, and PLA/PBAT increased bacterial module hubs, network hubs, and connectors in composting compared to control, but might enrich pathogens. Phylogenetic bin-based null model analysis indicated that stochastic processes obviously shaped the communities on PLA/PBAT plastisphere, but compare to control, PLA/PBAT plastics enhanced the contribution of deterministic processes on composting bacterial community assembly. These findings deeply understood the assembly patterns and diversity of plastisphere and composting processes, laying down a foundation on applying biodegradable plastics under the classification of domestic garbage.