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This study aimed to investigate the effect of Bacillus aryabhattai (LSG3-7) and Bacillus mojavensis (LSG3-8) on growth performance, antioxidant capacity, and immune response in Rhynchocypris lagowskii (Dybowski, 1869), at the trial and challenge periods. A 630 healthy fish (10.76 ± 0.05) were randomly divided into six groups: control group (D1) was fed the basal diet, D2 and D3 were supplemented with LSG 3-7 and LSG3-8 (1 × 10 8  CFU/g) for both of them, whereas D4 was supplemented with a mixture of both bacteria (0.5 × 10 8  CFU/g each), and D5 was supplemented with LSG3-7 0.75 × 10 8  CFU/g + LSG3-8 0.25 × 10 8  CFU/g, and D6 supplemented with LSG3-7 0.25 × 10 8  CFU/g + LSG3-8 0.75 × 10 8  CFU/g. After the trial, Aeromonas hydrophila was used in a challenge test for 14 days. Treatments showed significant differences (p < 0.05) in growth performance and antioxidant capacity (CAT, CuZn-SOD, GPX) in the liver and intestine compared to the control. The antioxidant-related genes CAT, CuZn-SOD, GPX, and Nrf2 in the liver and intestine showed upregulation compared with the control group. Serum IgM, LZM, C3, C4, and AKP showed a favorable superiority (p < 0.05) in treatments (D2 - D6) at the trial and challenge test compared to controls. In parallel, immune-related genes (IgM, NF-κB, TLR-1, TLR-2, and MyD88) showed an up-regulated level (p < 0.05) in treatments (D2 - D6) compared to the control. In addition, pro-inflammatory cytokines (IL-1, TNF-α) showed a downregulated level in treatments (D2 - D6). After the challenge test, the immune-related genes in the liver and muscle showed an up-regulated level in treatments compared to the controls. The survival rate showed a significant increase (p < 0.05) in the treatment groups (D2 - D6) compared to the control. Overall, individuals and the bacterial mixture of B. aryabhattai and B. mojavensis could improve the growth performance, antioxidant capacity, immune capacity, and survival rate of R. lagowskii and prevent side effects of A. hydrophila. However, B. mojavensis showed a slight improvement compared to B. aryabhattai without a significant difference between them., Competing Interests: Declaration of competing interest The authors report no declarations of interest., (Copyright © 2023. Published by Elsevier Ltd.)

Objective: The potential effects of quercetin and gentamicin combination on the bacteriostatic activity and biofilm formation of Pseudomonas aeruginosa (PA) were examined, and the findings provided a theoretical basis for the development of quercetin as a new biofilm inhibitor., Methods: The minimum inhibitory concentration (MIC) of eight PAs was determined by microdilution method and the partial inhibitory concentration index (FICI) of the combined drug was analyzed by micro-dilution method. Thereafter, the lowest film inhibitory concentration (MBIC) of quercetin and gentamicin alone and in combination was evaluated by crystal violet staining. Finally, scanning electron microscopy (SEM) and laser confocal microscopy (CLSM) were used to decipher the inhibitory effect of the combination on biofilm formation., Outcome: The antibacterial activity of quercetin alone was relatively weak, but after combination with gentamicin, the antibacterial activity was significantly enhanced, as evident by FICI of 0.28 and 0.53 and manifested as synergistic or additive effect, which indicated that quercetin can enhance gentamicin antibacterial activity. The results of crystal violet staining revealed that quercetin and gentamicin alone exhibited a similar biofilm formation inhibitory effect, but the inhibitory effect was substantially weaker, and the antibiofilm activity was stronger and exhibited a dose-dependent response after the combination of the two with 1/2FICI. The results of scanning electron microscopy and laser confocal microscopy also showed that the treatment of PA biofilm after combining quercetin and gentamicin with 1/2FICI could completely destroy the spatial structure of the complete biofilm, significantly reduce the thickness of bacteria, and markedly reduce the proportion of viable bacteria in the membrane., Conclusion: The combination of quercetin and gentamicin can effectively inhibit the formation of PA as well as its biofilm, and exhibit synergistic and additive effects., Competing Interests: Declaration of competing interest The authors declare that the research was conducted without any commercial or financial relationships that could be construed as a potential conflict of interest. The authors declare no conflicts of interest., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Probiotics sourced from fish intestinal microbiota have a merit over other bacterial sources due to colonization ability and effective time. This study aimed to evaluate the bacilli isolated from the Rhynchocypris lagowskii intestines and their validity as a probiotic. Three isolates were selected (LSG 2-5, LSG 3-7, and LSG 3-8) and defined by morphological and 16S rRNA analysis as Bacillus velezensis, Bacillus aryabhattai, and Bacillus mojavensis, respectively. Results showed the strain tolerant abilities to gastrointestinal fluid, bile salt, pH, and temperature expotures. Additionally, all bacterial strains showed anti-pathogenic activity against at least four strains out of six tested pathogen strains (Staphylococcus aureus, Aeromonas hydrophila, Escherichia coli, Aeromonas veronii, Edwardsiella, and Aeromonas sobria). The bacterial strains also showed a high percentage of co-aggregation activity, more than 70%, with Aer. hydrophile, Staph. epidermidis, and Klebsiella aerogenes. At the same time, the results of competition, rejection, and substitution activity with Aer. hydrophila and Aer. veronii indicated the ability of the isolated strains to reduce the adhesion of pathogens to mucin. All strains showed safety properties, non-hemolytic, and sensitivity characteristics for most of tested antibiotics. In vivo test after injecting these strains into fish at various concentrations showed no side effects in the internal or external organs of fish compared to controls, proving that this is safe for these fish. Furthermore, the three strains produced lipase, amylase, and protease enzymes. The strains also showed bile salt hydrolase activity and biofilm formation, allowing them to tolerate stressful conditions. Conclusion: Based on these strains characteristics and features, they could be considered a promising candidate probiotic and can be used as an anti-pathogenic, especially in aquaculture., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Mastitis in dairy cows affects milk quality and thereby constrains the development of the dairy industry. A clear understanding of the pathogenesis of mastitis can help its treatment. Mastitis is caused by the invasion of pathogenic bacteria into the mammary gland through the mammary ducts. However, recent studies suggested that an endogenous entero-mammary pathway in dairy cattle might also be playing an important role in regulating mastitis. Also, probiotic intervention regulating host gut microbes has become an interesting tool to control mastitis. This review discusses the association of gastrointestinal microbes with mastitis and the mechanism of action of probiotics in dairy cows to provide new ideas for the management of mastitis in large-scale dairy farms., Competing Interests: Declaration of competing interest The authors declare that the research was conducted without any commercial or financial relationships that could be construed as a potential conflict of interest. The authors declare no conflicts of interest., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

This study aimed to investigate the presence of eight virulence genes (ace, asa1, esp, efaA, gelE, cylA, agg, fsr) in Enterococcus from a variety of animals and to explore the drug resistance and pathogenicity. This could provide a theoretical basis for clinical treatment of Enterococcus infections. Anal swabs from pigs, chickens, cattle, and dogs in farms and pet hospitals were collected for Enterococcus isolation and identification. Eight virulence genes were detected (PCR method), and drug resistance was assessed (drug-sensitive paper method). The strains containing different virulence genes were then divided into EV1, EV2, and EV3 groups. The LD 50 and pathogenicity was examined by intra-peritoneal injection to infect mice. Differences were found in the detection rates of virulence genes in Enterococcus from the different animals. The highest overall detection rate was for the esp gene (78.0%), and the lowest for the cylA gene (15.5%). Eight genes were detected most frequently in Enterococcus from dogs and least frequently from cattle. Among the Enterococcus strains from four variety of animals, drug resistance was highest against sulfamethoxazole (100%), cefotaxime (>97%), and cefotaxitin (>93%). Drug resistance was lowest against vancomycin (0%), levofloxacin (<12%) and ciprofloxacin (<13%). The LD 50 for each of the three groups was EV1 LD50 =8.71×10 9 CFU， EV2 LD50 =2.34×10 10 CFU，and EV3 LD50 =9.33×10 10 CFU. The Enterococcus12LD 50 dose group caused significant clinical symptoms in mice, with pathological effects on the heart, liver, lungs, and kidneys, and particularly on the urinary system. The abundance of Enterococcus virulence genes, drug resistance, and pathogenicity vary among different animal origins, and the pathology caused by Enterococcus requires effective treatment protocols based on species and regional characteristics., Competing Interests: Declaration of competing interest The authors declare that the research was conducted without any commercial or financial relationships that could be construed as a potential conflict of interest. The authors declare no conflicts of interest., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Diseases of fish caused by pathogenic bacteria are an important constraint on aquaculture production. Antibiotics have been widely used to control infectious diseases, but this has led to the emergence of drug-resistant bacteria and affected human health. In this context, probiotics are used as an alternative to antibiotics for the prevention and control of diseases in aquaculture. The aim of this study was to obtain probiotic candidate strains of Bacillus spp. from the gut of Rhynchocypris Lagowskii. Strains were screened by enzyme-producing ability, antagonism assay and antibiotic susceptibility. The safety of the strains to host fish has also been established. The isolated Bacillus licheniformis (LSG1-1) and Bacillus subtilis (LSG2-1) were characterized and performed well in tolerance experiments. In addition, LSG1-1 and LSG2-1 were detected to have higher self-aggregation ability and surface hydrophobicity. In the in vitro adhesion model, LSG1-1 and LSG2-1 showed good adhesion ability and had obvious adhesion inhibitory effect on three pathogens of Aeromonas. Based on the characteristics observed so far, Bacillus licheniformis LSG1-1 and Bacillus subtilis LSG2-1 could form potential probiotic candidates in the digestive tract of R. lagowskii to help combat diseases in aquaculture., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The goal of the study was to determine the ameliorative effects of dietary alpha-lipoic acid (α-LA) on deltamethrin (DEL)-induced immunosuppression and oxidative stress in northern snakehead (Channa argus). The northern snakeheads (15.38 ± 0.09 g) were exposed to DEL (0.242 μg/L) and fed with diets supplemented α-LA at 300, 600, and 900 mg/kg. After the 28-day exposure test, we obtained the following results: i) α-LA alleviates DEL-induced liver injury by reversing the increase of the serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels and liver cytochrome P450 enzymes (Cytochrome P450 (cyp)1a and cyp1b) expression levels. ii) α-LA can reverse the DEL-induced reduction of serum complement 4 (C4), C3, immunoglobulin M (IgM), and lysozyme (LYS) levels and the increase of liver and intestine nuclear factor kappa B (nf-κb) p65, tumor necrosis factor (tnf)-α, interleukin (il)-1β, il-8, and il-6 gene expressions, while il-10 expression levels showed the opposite result. iii) α-LA reversed the reduction of superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), glutathione-S-transferase (GST) and glutathione peroxidase (GSH-Px) levels in the liver and intestine induced by DEL, while malondialdehyde (MDA) showed the opposite result. iv) α-LA reversed the reduction of Cu/Zn sod, nuclear factor erythroid 2-related factor 2 (nrf2), NAD (P)H: quinone oxidoreductase (nqo)1, and heme oxygenase (ho)-1 antioxidant gene expression levels in the liver and intestine induced by DEL. Therefore, our study indicated that optimal α-LA (600 mg/kg) could attenuate DEL-induced toxicity (including liver damage, immunotoxicity, and oxidative stress) in northern snakehead via Nrf2/NF-κB signaling pathway. This is the first research that explores the alleviated effects of α-LA on DEL-induced toxicity damage in fish. This study provides a positive measure to reduce the toxicity damage caused by DEL to aquatic animals, and provides a theoretical basis for exploring the regulation mechanism of α-LA in toxic substances., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The study was the first time to explore the positive effects of α-LA on growth performance, antioxidant capability, immunity, and disease resistance of northern snakehead (Channa argus). Five hundred and forty northern snakehead fish (initial body weight: 8.74 ± 0.12 g (mean ± SE)) were randomly allocated into six groups with three replicates each. Six diets supplemented with α-LA at doses of 0 (CON), 300 (LA300), 600 (LA600), 900 (LA900), 1200 (LA1200), and 1500 (LA1500) mg/kg were fed to northern snakehead for 8 weeks. The results demonstrated that, when compared with the control group, optimal dietary α-LA increased the weight gain (WG), protein efficiency ratio (PER), and specific growth rate (SGR) and reduced the feed conversion ratio (FCR) of the fish (P < 0.05). Also, optimal dietary α-LA enhanced the immune-related parameters and antioxidant enzyme parameters levels in the head kidney, spleen, and liver of northern snakehead (P < 0.05). Dietary α-LA upregulated the mRNA expression levels of anti-inflammatory cytokines (il10 and tgfβ) and antioxidant related genes (gst, gsh-px, gr and Cu/Zn sod), down-regulated the pro-inflammatory cytokines (il1β, il8, il12 and tnfα) mRNA levels in the liver, spleen and head kidney of the northern snakehead (P < 0.05). The above results demonstrated that optimal dietary α-LA showed enhancement effects on the growth, antioxidant and anti-inflammatory capability, and immune response of northern snakehead. The survival rates in all α-LA treatments were significantly raised after the challenge with Aeromonas veronii (P < 0.05). Based on the quadratic regression analysis of WG, GSH-Px, LYS, and il1β, the optimal dietary α-LA levels were estimated to be 737.0, 775.0, 890.0, and 916.7 mg/kg, respectively. Considering the overall responses in growth performance, antioxidant status, immune response, and inflammatory factors, the recommended dose of α-LA in the diet of fish is 737.0-916.7 mg/kg., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The purpose of this study was to investigate the effect of Bacillus amyloliquefaciens LSG2-8 on the growth performance, immune function, antioxidant capacity, and disease resistance of Rhynchocypris lagowskii. Fish were fed with the feed containing five levels such as 0, 1.0 × 10 6 , 1.0 × 10 7 , 1.0 × 10 8, and 1.0 × 10 9  CFU/g of the B. amyloliquefaciens LSG2-8 for 56 days. After 56 days of feeding, twenty four fish were randomly selected to test various growth, immune and antioxidant parameters. Ten fish were challenged with Aeromonas hydrophila for 14 days; the mortality rate was recorded 14 days after infection. The results showed that B. amyloliquefaciens LSG2-8 could significantly increase the growth parameters of R. lagowskii's, such as final body weight, weight gain rate, specific growth rate, and feed efficiency (p < 0.05). Further examination revealed the activity of antioxidant enzymes, Nrf-2 mRNA, and Keap-1 mRNA gene expression in the intestine and liver, and the serum immune index of R. lagowskii in the 1.0 × 108 CFU/g were all significantly higher compared to the other groups. Furthermore, fish fed a diet supplemented with B. amyloliquefaciens LSG2-8 had a significantly lower (p < 0.05) post-challenge mortality rate than the control fish. In summary, the research results showed that B. amyloliquefaciens LSG2-8 could improve the growth performance, immune function, antioxidant capacity, and disease resistance of R. lagowskii and be used in aquaculture., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

This study aims to evaluate the effects of dietary α-lipoic acid (α-LA) on bioaccumulation, oxidative stress, apoptosis, and inflammation in Channa argus after 28 d of lead (Pb) exposure. A total of 300 fish were divided into five groups: the first group was the control group and the other four groups were exposed to waterborne Pb (800 ppb) and fed α-LA diets supplemented with 0, 300, 600, and 900 mg/kg. The results demonstrated that dietary α-LA effectively reduced the Pb accumulation in the liver, kidney, gill, intestine, and muscle of C. argus after exposure to Pb. Meanwhile, dietary α-LA reversed alterations in the biochemical parameters (Alanine aminotransferase (ALT), lactate dehydrogenase (LDH), aspartate aminotransferase (AST), blood urea nitrogen (BUN), cortisol (COR), and creatinine (CRE)) and immunity parameters (myeloperoxidase (MPO), complement 3 (C3), lysozyme (LYS), complement 4 (C4), C-reactive protein (CRP), and immunoglobulin M (IgM)) in the serum of fish caused by Pb. Pb-induced reduction of antioxidant enzyme activities (Catalase (CAT), glutathione reductase (GR), superoxide dismutase (SOD), glutathione (GSH), glutathione peroxidase (GSH-Px)) was inhibited by dietary α-LA. And malondialdehyde (MDA) and protein carbonyl (PC) content exhibited an opposite trend. Meanwhile, dietary supplemented with α-LA was found to relieve Pb-induced oxidative stress by downregulating Keap1 mRNA expression levels and upregulating the expression levels of CAT, nuclear factor erythroid 2-related factor 2 (Nrf2), GSH-Px, and Cu/Zn SOD. Furthermore, α-LA supplementation reversed Pb-induced upregulation of pro-inflammatory genes (interleukin (IL)-6, IL-1β, tumor necrosis factor α (TNF-α), and nuclear factor kappa B (NF-κB)), Pro-apoptotic genes (Bcl-2-associated X (Bax), caspase (Cas)-3, and tumor protein p53 (p53)) and Hsp70, and downregulation of anti-inflammatory genes (IL-10, inhibitor of κBα (IκBα), and transforming growth factor β (TGF-β)) and anti-apoptosis gene (B-cell lymphoma-2 (Bcl-2)). Overall, dietary α-LA supplementation could enhance the innate immunity and antioxidant capacity of fish, attenuating the Pb accumulation, and cell apoptosis after being exposed to Pb. Furthermore, dietary α-LA could relieve Pb-induced inflammatory response and oxidative stress of fish via regulating NF-κB and Nrf2 signaling, respectively., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Aeromous veronii is a severe pathogen that can infect aquatic organisms and mammals also causes irreparable damage to fish aquaculture. Analysis of the results of epidemiological investigations have revealed that its tolerance to drugs and the virulence of A. veronii have increased in recent years. Most of the researches on A. veronii focuse on the strain isolation, identification, and drug susceptibility. However, we do not know so much about the molecular mechanism of the pathogenesis on A. veronii. Here we identified and obtained the highly expressed TH0426 Nucleoside Diphosphate Kinases (NDK) of A. veronii. We first constructed a mutant strain (△-ndk) by generating an in-frame deletion of the ndk gene, to investigate the functional role in A. veronii TH0426. The ability in the adhesion and invasion of EPC cells and biofilm formation significantly reduced of the △-ndk strain. The motility test showed that the ndk gene affected on the swimming ability, while did not affect the swarming motility. Compared with the wild-type strain TH0426, the pathogenicity of △-ndk strain to zebrafish reduced severely. Besides, the ndk gene has affected the apoptosis rate of A. veronii TH0426. These results would help to demonstrate the function of ndk further and realize the pathogenesis on A. veronii., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Lactic acid bacteria (LAB) has been documented to promoting growth, enhancing immunity and disease resistance. In this study, we aimed to evaluate the single or conjoint effects of Lactococcus lactis L19 (Genbank: MT102745.1) and Enterococcus faecalis W24 (Genbank: MT102746.1) isolated from the intestine of Channa argus (C. argus) on growth performance, immune response and disease resistance of C. argus. A total of 720 apparently healthy C. argus (9.50 ± 0.03 g) were randomly divided into four equal groups. Fish were fed with a basal diet (CK) supplemented with L. lactis (L19), E. faecalis (W24), and L. lactis L19 + E. faecalis W24 (L + W) at 1.0 × 10 8  cfu/g basal diet for 56 days. After feeding, the final body weight (FBW), weight gain (WG), feed efficiency ratio (FER), specific growth rate (SGR) and protein efficiency ratio (PER) had significantly increased (p < 0.05), especially with L19. The results indicated that single or conjoint administration of LAB as potential probiotics can induce high levels of IgM, ACP, AKP, LZM, C3 and C4 activity in serum, which may effectively induce humoral immunity, and L19 induce even higher levels. Meanwhile, when compared to CK group, the results of qPCR showed that LAB administration significantly up-regulated (p < 0.05) the expression of IL-1β, IL-6, IL-10, TNF-α, IFN-γ, HSP70, HSP90, TGF-β in the spleen, head kidney, gill, liver and intestine of C. argus. After challenge with Aeromonas veronii, the survival rates in all LAB-fed groups were significantly higher (p < 0.05) than that of the CK group, and the L19 group showed the highest (63.3%) disease resistance. Our data indicated that L. lactis L19 and E. faecalis W24, as a feed additive at 1.0 × 10 8  cfu/g feed, could promote growth performance, enhance immune response and disease resistance of C. argus, with greatest effects in fish fed L. lactis L19 for 56 days. Hence, these LAB additives could be used as promising probiotics for C. argus. L19 was more effective than W24 or the mixture of the two for promoting growth performance, enhancing immune response and disease resistance of C. argus., Competing Interests: Declaration of competing interest The authors declare that they have no competing interests., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

In the present study, we constructed two recombinant Lactobacillus casei (L. casei) Lc-pPG-1-AcrV (surface-displayed) and Lc-pPG-2-AcrV (secretory) constitutively expressing AcrV protein of Aeromonas veronii (A. veronii). Expression of recombinant AcrV protein was verified by western blot and immunofluorescence technique. Compared with PBS group, the final weight (FW), weight gain (WG) and specific growth rate (SGR) of fish fed Lc-pPG-1-AcrV, Lc-pPG-2-AcrV and Lc-pPG diets after 56 days observed significantly increase (p < 0.05), while the feed conversion ratio (FCR) showed a significantly decrease (p < 0.05). The recombinant L. casei strains were orally administrated to crucian carp, and significant increased (p < 0.05) the immunoglobulin M (IgM), elevated the acid phosphatase (ACP), alkaline phosphatase (AKP), lysozyme (LZM) and superoxide dismutase (SOD) activity in serum. Moreover, leukocytes phagocytosis percentage and index of the recombinant L. casei were both enhanced. The results demonstrated that the recombinant L. casei could elicit systemic immune responses and increase the serum immunological index. The Interleukin-10 (IL-10), Interleukin-1β (IL-1β), interferon-γ (IFN-γ) and Tumor Necrosis Factor-α (TNF-α) levels in liver, spleen, kidney and intestine have up regulated significantly in tissues (p < 0.05), suggesting that the recombinant L. casei has the ability to induce expression of cytokines and enhance the innate immune response. Higher survival rates were exhibited that crucian carp immunized with Lc-pPG-1-AcrV (67.5%) and Lc-pPG-2-AcrV (52.5%) after challenge with A. veronii. In conclusion, these two recombinant L. casei vaccine were effective in improving crucian carp growth, immunity response and disease resistance. The recombinant L. casei strains may be a promising candidate for the development of an oral vaccine against A. veronii., Competing Interests: Declaration of competing interest The authors declare that they have no competing interests., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Myeloperoxidase (MPO) is a ferrous lysosomal protein with many immune functions that belongs to the heme peroxidase enzyme. In this study, the functions of MPO in the northern snakehead (Channa argus) were investigated by cloning an MPO cDNA sequence with a full length of 3181 bp. Homology analysis showed that northern snakehead MPO gene had the highest (81%) homology with mandarin fish (Siniperca chuatsi). In healthy northern snakehead, the MPO gene was expressed in the head-kidney, kidney, heart, gill, spleen, liver, and muscles but not midgut. After the northern snakehead was infected with Aeromonas veronii, the MPO gene expression varied in different tissues with low level in spleen, liver, gill and muscle, fluctuated in kidney and head-kidney and showed high level in heart. The result indicated that MPO might play an important role in the antimicrobial immune response of the northern snakehead., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Site selection is an important and necessary issue for waste management in fast-growing regions. Because of the complexity of waste management systems, the selection of the appropriate solid waste landfill site requires consideration of multiple alternative solutions and evaluation criteria. Based on actual conditions of the study area, we considered economic factors, calculated criteria weights using the analytical hierarchy process (AHP), and built a hierarchy model for solving the solid waste landfill site-selection problem in Beijing, China. A geographic information system (GIS) was used to manipulate and present spatial data. All maps are graded from 1 (lowest suitability) to 5 (highest suitability) using spatial information technologies. The candidate sites were determined by aggregation based on the criteria weights. The candidate sites are divided by 'best', 'good' and 'unsuitable' landfill areas. Best landfill areas represent optimal sites; good landfill areas can be used as back-up candidate sites. Our work offers a sitting methodology and provides essential support for decision-makers in the assessment of waste management problems in Beijing and other rapidly developing cities in developing countries.