Large amounts of waste activated sludge are generated daily worldwide, posing significant environmental challenges. Anaerobic fermentation is a promising method for sludge disposal, but it has two technical bottlenecks: the availability of short-chain fatty acids (SCFAs)-producing substrates and SCFAs consumption by methanogenesis. This study proposes a pretreatment strategy combining sodium percarbonate (SPC) and magnetite (Fe3O4) to address these issues. Under optimized conditions (20 mg Fe3O4/g TSS and 15 mg SPC/g TSS), SCFAs production increased to 3244.10 ± 216.31 mg COD/L, about 3.06 times the control (1057.29 ± 35.06 mg COD/L) and surpassing reported treatments. The combined pretreatment enhanced the disruption of extracellular polymeric substances, increased the release of biodegradable matters, improved acidogenesis enzyme activities, and inhibited methanogenesis. Additionally, it increased NH4+-N release in favor of the recovery of phosphorus from sludge residual. This study demonstrates an efficient pretreatment for high SCFAs production and resource recovery from WAS.

Alzheimer\'s disease (AD) is a neurodegenerative disease that is known to accumulate amyloid-β (Aβ) and tau protein. Clinical studies have not identified pathogenesis mechanisms or produced an effective cure for AD. The Aβ monoclonal antibody lecanemab reduces Aβ plaque formation for the treatment of AD, but more studies are required to increase the effectiveness of drugs to reduce cognitive decline. The lack of AD therapy targets and evidence of an association with an acute neuroinflammatory response caused by several bacteria and viruses in some individuals has led to the establishment of the infection hypothesis during the last 10 years. How pathogens cross the blood-brain barrier is highly topical and is seen to be pivotal in proving the hypothesis. This review summarizes the possible role of the gut microbiome in the pathogenesis of AD and feasible therapeutic approaches and current research limitations.

The beneficial effects of probiotics for the improvement of metabolic disorders have been studied intensively; however, these effects are evident in a probiotic strain-specific and disease-specific manner. Thus, it is still essential to evaluate the efficacy of each strain against a target disease. Here, we present an anti-obese and anti-diabetic probiotic strain, Lactiplantibacillus plantarum APsulloc331261 (GTB1™), which was isolated from green tea and tested for safety previously. In high-fat-diet-induced obese mice, GTB1™ exerted multiple beneficial effects, including significant reductions in adiposity, glucose intolerance, and dyslipidemia, which were further supported by improvements in levels of circulating hormones and adipokines. Lipid metabolism in adipose tissues was restored through the activation of PPAR/PGC1α signaling by GTB1™ treatment, which was facilitated by intestinal microbiota composition changes and short-chain fatty acid production. Our findings provide evidence to suggest that GTB1™ is a potential candidate for probiotic supplementation for comprehensive improvement in metabolic disorders.

As a food contaminant that can be quickly absorbed through the gastrointestinal system, furan has been shown to disrupt the intestinal flora and barrier. Investigation of the intestinal toxicity mechanism of furan is of great significance to health. We previously identified the regulatory impact of salidroside (SAL) against furan-provoked intestinal damage, and the present work further explored whether the alleviating effect of SAL against furan-caused intestinal injury was based on the intestinal flora; three models, normal, pseudo-germ-free, and fecal microbiota transplantation (FMT), were established, and the changes in intestinal morphology, barrier, and inflammation were observed. Moreover, 16S rDNA sequencing observed the variation of the fecal flora associated with inflammation and short-chain fatty acids (SCFAs). Results obtained from the LC-MS/MS suggested that SAL increased furan-inhibited SCFA levels, activated the mRNA expressions of SCFA receptors (GPR41, GPR43, and GPR109A), and inhibited the furan-activated TLR4/MyD88/NF-κB signaling. Analysis of protein-protein interaction further confirmed the aforementioned effects of SAL, which inhibited furan-induced barrier damage and intestinal inflammation.

Short-chain fatty acids (SCFAs), such as acetate, propionate, and butyrate, modulate immune cell functions, particularly macrophages. This review explores the potential therapeutic applications of SCFAs in pulmonary fungal infections, a critical concern due to their high mortality rates and antifungal resistance. SCFAs enhance macrophage functions by promoting phagosome-lysosome fusion, increasing reactive oxygen species production, and balancing cytokine responses. Pulmonary fungal infections, caused by pathogens like Aspergillus fumigatus, are prevalent in immunocompromised patients, including those with diabetes, chronic obstructive pulmonary disease, and those on high-dose corticosteroids. SCFAs have shown promise in improving macrophage function in these contexts. However, the application of SCFAs must be balanced against potential side effects, including gut microbiota disruption and metabolic disorders. Further research is needed to optimize SCFA therapy for managing pulmonary fungal infections.

Ulcerative colitis (UC) is an autoimmune disease in which the immune system attacks the colon, leading to ulcer development, loss of colon function, and bloody diarrhea. The human gut ecosystem consists of almost 2000 different species of bacteria, forming a bioreactor fueled by dietary micronutrients to produce bioreactive compounds, which are absorbed by our body and signal to distant organs. Studies have shown that the Western diet, with fewer short-chain fatty acids (SCFAs), can alter the gut microbiome composition and cause the host\'s epigenetic reprogramming. Additionally, overproduction of H2S from the gut microbiome due to changes in diet patterns can further activate pro-inflammatory signaling pathways in UC. This review discusses how the Western diet affects the microbiome\'s function and alters the host\'s physiological homeostasis and susceptibility to UC. This article also covers the epidemiology, prognosis, pathophysiology, and current treatment strategies for UC, and how they are linked to colorectal cancer.

OBJECTIVE: To observe the effects of acupuncture on blood pressure, fecal short-chain fatty acids (SCFAs) and toll-like receptor 4 (TLR4)/myeloid differentiation factor 88 (MyD88)/nuclear factor-κB (NF-κB) signaling pathway in spontaneously hypertensive rats (SHR), and to explore the mechanism of acupuncture for anti-hypertension.
METHODS: Twenty-four male SHR of SPF grade were randomly divided into a model group, a western medication group, an acupuncture group and a sham acupuncture group, with 6 rats in each group, and 6 male Wistar-Kyoto rats were selected as the blank group additionally. Hydrochlorothiazide solution was given by gavage in the western medication group; acupuncture was applied at bilateral \"Renying\" (ST 9) and \"Zusanli\" (ST 36) in the acupuncture group, 20 min a time; acupuncture was applied at the non-meridian and non-acupoint points close to bilateral \"Renying\" (ST 9) and \"Zusanli\" (ST 36) in the sham acupuncture group, 20 min a time. The intervention was adopted once a day for 4 weeks continuously in each group. The systolic blood pressure (SBP) of the caudal artery was measured before intervention and after 1, 2, 3 and 4 weeks of intervention. After intervention, the morphology of colonic tissue was observed by HE staining; the fecal level of SCFAs was detected by gas chromatography; the serum levels of interleukin (IL)-6, IL-1βand tumor necrosis factor-α (TNF-α) were detected by ELISA; the protein expression of TLR4, MyD88 and NF-κB p65 in the mesenteric artery was detected by Western blot.
RESULTS: Compared with the blank group, in the model group, the SBP was increased (P<0.05), significant pathological changes could be found in the colonic tissue, the fecal SCFAs level was decreased (P<0.05), the serum levels of IL-6, IL-1β and TNF-α were increased (P<0.05), the protein expression of TLR4, MyD88 and NF-κB p65 in the mesenteric artery was increased (P<0.05). Compared with the model group, the SBP after 2, 3 and 4 weeks of intervention was decreased (P<0.05), the serum levels of IL-6, IL-1β and TNF-α were decreased (P<0.05) in the acupuncture group and the western medication group; the mucosal epithelium of colonic tissue was intact, the number of intestinal glands was abundant, the fecal SCFAs level was increased (P<0.05), and the protein expression of TLR4, MyD88 and NF-κB p65 in the mesenteric artery was decreased (P<0.05) in the acupuncture group. Compared with the sham acupuncture group, the SBP after 2, 3 and 4 weeks of intervention was decreased (P<0.05), the fecal SCFAs level was increased (P<0.05), the serum levels of IL-6, IL-1β and TNF-α were decreased (P<0.05), the protein expression of TLR4, MyD88 and NF-κB p65 in the mesenteric artery was decreased (P<0.05) in the acupuncture group.
CONCLUSIONS: Acupuncture at bilateral \"Renying\" (ST 9) and \"Zusanli\" (ST 36) can effectively play an anti-hypertensive role in SHR. Its mechanism may be related to regulating fecal SCFAs level and inhibiting the TLR4/MyD88/NF-κB signaling pathway.
目的：观察针刺对自发性高血压大鼠（SHR）血压、粪便短链脂肪酸（SCFAs）及toll样受体4（TLR4）/髓样分化因子88（MyD88）/核因子κB（NF-κB）信号通路的影响，探讨针刺降压的作用机制。方法：将24只SPF级雄性SHR随机分为模型组、西药组、针刺组和假针组，每组6只；另设6只Wistar-Kyoto（WKY）大鼠为空白组。西药组予氢氯噻嗪溶液灌胃；针刺组针刺双侧“人迎”“足三里”，每次20 min；假针组针刺双侧“人迎”“足三里”附近的非经非穴点，每次20 min。均每日1次，持续4周。干预前及干预第1、2、3、4周后测量各组大鼠尾动脉收缩压（SBP）；HE染色观察大鼠结肠组织形态；气相色谱-质谱联用仪检测大鼠粪便SCFAs含量；ELISA法检测大鼠血清白细胞介素（IL）-6、IL-1β和肿瘤坏死因子-α（TNF-α）含量；Western Blot法检测大鼠肠系膜动脉中TLR4、MyD88和NF-κB p65蛋白表达。结果：与空白组比较，模型组大鼠SBP升高（P<0.05），结肠组织有明显病理变化，粪便SCFAs含量降低（P<0.05），血清IL-1β、IL-6和TNF-α含量升高（P<0.05），肠系膜动脉中TLR4、MyD88、NF-κB p65蛋白表达升高（P<0.05）。与模型组比较，针刺组和西药组大鼠干预2、3、4周后SBP降低（P<0.05），血清IL-1β、IL-6和TNF-α含量降低（P<0.05）；针刺组大鼠结肠组织黏膜上皮完整，肠腺数量丰富，粪便SCFAs含量升高（P<0.05），肠系膜动脉中TLR4、MyD88、NF-κB p65蛋白表达降低（P<0.05）。与假针组比较，针刺组干预2、3、4周后SBP降低（P<0.05），粪便SCFAs含量升高（P<0.05），血清IL-1β、IL-6和TNF-α含量降低 （P<0.05），肠系膜动脉中TLR4、MyD88、NF-κB p65蛋白表达降低（P<0.05）。结论：针刺双侧“人迎”“足三里”可有效降低SHR血压，其机制可能与调节粪便SCFAs含量、抑制TLR4/MyD88/NF-κB信号通路有关。.

Diarrheagenic Escherichia coli (DEC) is the main cause of diarrhea in children under five years old. The virulence of DEC is tightly regulated by environmental signals influenced by the gut microbiota and its metabolites. Short-chain fatty acids (SCFAs) are the main metabolic product of anaerobic fermentation in the gut, but their role in DEC diarrhea has not yet been established. In this study, we determine the levels of acetate, propionate, and butyrate in stool samples from children with diarrhea caused by DEC, and we identify bacteria from the fecal gut microbiota associated with the production of SCFAs. The microbiota and SCFAs levels in stool samples obtained from 40 children with diarrhea and 43 healthy children were determined by 16S rRNA gene sequencing and HPLC, respectively. Additionally, shotgun metagenomics was used to identify metagenome-assembled genomes (MAGs) in a subgroup of samples. The results showed significantly higher levels of all SCFAs tested in diarrheal samples than in healthy controls. The abundance of Streptococcus sp., Limosilactobacillus, Blautia, Escherichia, Bacteroides, Megamonas, and Roseburia was higher in the DEC group than in healthy individuals. Functional analysis of bacteria and their main metabolic pathways made it possible to identify species MAGs that could be responsible for the detected SCFAs levels in DEC-positive diarrhea. In conclusion, based on our results and published data, we suggest that SCFAs may be important in the crosstalk between the microbiota and DEC pathogens in the gut.

The gastrointestinal tract is home to trillions of diverse microorganisms collectively known as the gut microbiota, which play a pivotal role in breaking down undigested foods, such as dietary fibers. Through the fermentation of these food components, short-chain fatty acids (SCFAs) such as acetate, propionate, and butyrate are produced, offering numerous health benefits to the host. The production and absorption of these SCFAs occur through various mechanisms within the human intestine, contingent upon the types of dietary fibers reaching the gut and the specific microorganisms engaged in fermentation. Medical literature extensively documents the supplementation of SCFAs, particularly butyrate, in the treatment of gastrointestinal, metabolic, cardiovascular, and gut-brain-related disorders. This review seeks to provide an overview of the dynamics involved in the production and absorption of acetate, propionate, and butyrate within the human gut. Additionally, it will focus on the pivotal roles these SCFAs play in promoting gastrointestinal and metabolic health, as well as their current therapeutic implications.

Nitrate photolysis has become an efficient, low-cost and promising technology for emerging contaminants removal, while its performance and mechanism for waste activated sludge (WAS) treatment is still unknown. This study innovatively introduced nitrate photolysis for WAS disintegration, and investigated the effect of nitrate addition (150-375 mg N/L) for short-chain fatty acids (SCFAs) production during anaerobic fermentation (AF). The results showed that nitrate photolysis significantly promoted the SCFAs production from WAS, and peaked at 280.7 mg/g VSS with 7-d fermentation with 150 mg N/L addition (150N-UV), which increased by 8.8-35.0 % and 10.7-23.3 % compared with other photolysis groups and sole nitrate groups. Effective release of the soluble organics was observed in the nitrate photolysis groups during AF, especially soluble proteins, reaching 1505.4 mg COD/L at 9 d in 150N-UV group, promoted by 7.0∼15.7 % than nitrate/nitrate photolysis groups. The model compounds simulation experiment further demonstrated the positive effect of nitrate photolysis on organics hydrolysis and SCFAs accumulation. The result of the radical capture and quenching verified the reactive oxygen species contributed more compared with reactive nitrogen species. Functional group analysis confirmed the effective bioconversion of the macromolecular organics during the fermentation. Moreover, the nitrate photolysis enhanced the enrichment of the functional consortia, including anaerobic fermentation bacteria (AFB), e.g., Fnoticella, Romboutsia, Gracilibacter and Sedimentibacter, and nitrate reducing bacteria (NRB), e.g., Acinerobacter and Ahniella. The macrogenetic analysis further revealed that glycolysis, amino acid metabolism, acetate metabolism and nitrogen metabolism were the dominating metabolic pathways during fermentation, and the abundance of the relevant genes were enhanced in 150N-UV group.