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In order to investigate the biological characteristics of avian pathogenic Escherichia coli (APEC) isolated in eastern China, a total of 243 isolates were isolated from diseased poultry on different farms during the period from 2007 to 2014. These isolates were characterized for serogroups (polymerase chain reaction and agglutination), the presence of virulence-associated genes ( fimC , iss , ompA , fyuA , stx2f , iroC , iucD , hlyE , tsh , cvaC , irp2 , and papC ) and class I integrons (polymerase chain reaction), drug susceptibilities (disk diffusion method) and the biofilm-forming abilities (semi-quantitative method). The results showed that the most predominant serogroups were O78 (87 isolates, 35.8%) and O2 (35 isolates, 14.4%). Gene profiling found that fimC and ompA were frequently distributed among the isolates and that 77.4% of the isolates were positive for class 1 integrons. Overall, isolates displayed resistance to tetracycline (97.5%), nalidixic acid (82.3%), ampicillin (81.1%), sulphafurazole (80.7%), streptomycin (79.0%), trimethoprim (78.2%) and cotrimoxazole (78.2%). Multiple-drug resistance was exhibited in 80.3% of the isolates, and the presence of class 1 integrons is associated with multidrug resistance. Finally, 151 isolates had the ability to form biofilms in vitro, and drug resistance seemed relative to biofilm-forming abilities. [ABSTRACT FROM AUTHOR]

Salmonella Pullorum (S. Pullorum) and Salmonella Gallinarum (S. Gallinarum) are the biovars of Salmonella enterica serovar Gallinarum that are responsible for pullorum disease and fowl typhoid, respectively, in poultry. Traditional serological methods fail to quickly differentiate between these biovars due to their identical O antigenic factors (O9 and O12). Although single nucleotide polymorphism (SNP)-based methods have been used to distinguish between the biovars, they often lack the required accuracy and effectiveness. In this study, we developed a PCR high resolution melt (PCR-HRM) assay, which targeted a SNP at position 665 of the fimH gene, for rapid differentiation between S. Pullorum and S. Gallinarum. Our method showed 100% specificity and was able to detect as little as 0.033 pg of S. Pullorum DNA and 0.027 pg of S. Gallinarum DNA. The PCR-HRM results for 547 clinical isolates were in complete agreement with traditional serological methods. This PCR-HRM assay significantly reduced identification time and provided high throughput, efficient testing. This makes it a practical and reliable tool for accurate differentiation between S. Pullorum and S. Gallinarum in clinical settings. [ABSTRACT FROM AUTHOR]

Salmonella enterica serovar Enteritidis (S. Enteritidis) is a zoonotic pathogen that can infect both humans and animals. Among the 13 types of fimbrial operons in S. Enteritidis, the highly conserved Peg fimbriae play a crucial role in the adhesion and invasion of S. Enteritidis into host cells but are not well studied. In this study, we identified the ATP synthase subunit alpha (ATPase α) as a ligand of Peg fimbriae using ligand blotting and mass spectrometry techniques. We confirmed the in vitro binding of ATPase α to the purified adhesion protein (PegD). Furthermore, we used siRNA to suppress the expression of ATPase α gene Atp5a1 in Leghorn male hepatoma (LMH) cells, which resulted in a significant reduction in the adhesion rate of S. Enteritidis to the cells (P < 0.05). The findings in this study provide insight into the mechanism of S. Enteritidis infection through Peg fimbriae and highlight the importance of ATPase α in the adhesion process. RESEARCH HIGHLIGHTS Ligand blotting was performed to screen the ligand of S. Enteritidis Peg fimbriae. Binding assay confirmed that ATPase α is the ligand of the Peg fimbriae. siRNA targeting ATPase α gene (Atp5a1) significantly reduced S. Enteritidis adhesion. [ABSTRACT FROM AUTHOR]

Salmonella enterica serovar Enteritidis (S. Enteritidis) poses a significant threat as a prevalent foodborne pathogen globally. Timely diagnostic methods are essential for effective management of S. Enteritidis infections. Herein, we establish a one-step LAMP-CRISPR/Cas12b method for a rapid, accurate, and convenient detection of S. Enteritidis. The entire reaction requires only 45 min without the need for specialized equipment. The platform exhibited 100% specificity with no cross-reactivity observed among 19 other Salmonella serovars and 9 non- Salmonella bacterial pathogens. Our method achieved a limit of detection of 30 copies per reaction. Compared with the traditional culture methods in practical analysis. S. Enteritidis positivity rates identified by one-step LAMP-CRISPR/Cas12b platform were 2.88% (6/208) including 3.14% (4/127) in chicken, 4.44% (2/45) in duck, and 0.0% (0/36) in pork, and a 100% concordance was observed between the traditional culture method and one-step LAMP-CRISPR/Cas12b platform. In summary, our findings underscore the simplicity and accuracy of the one-step LAMP-CRISPR/Cas12b platform for S. Enteritidis detection, with potential applications in resource-limited settings. • The simplicity and accuracy of the one-step LAMP-CRISPR/Cas12b platform for S. Enteritidis detection. • The one-step LAMP-CRISPR/Cas12b platform presents 100% consistency with traditional culture method. • A limit of detection of 30 copies per reaction mixture and can be finished within 1h. • The platform exhibited 100% specificity (3/3) with no cross-reactivity observed among other bacterial pathogens. [ABSTRACT FROM AUTHOR]

Infectious bronchitis virus (IBV) restricts cell tropism. Except for the Beaudette strain, other IBVs cannot infect mammalian cell lines. The limited cell tropism of other IBVs has hindered IBV vaccine development and research on the mechanisms of IBV infection. A novel Vero cell-adapted strain, HV80, has been previously reported. In this study, we constructed recombinants expressing the chimeric S glycoprotein, S1 or S2 subunit of strain H120 and demonstrated that mutations on S2 subunit are associated with the strain HV80 Vero cell adaptation. R687P or P687R substitution recombinants were constructed with the genome backbone of strains HV80 or H120. We found that the RRRR 690 /S motif at the S2′ cleavage site is crucial to the Vero cell adaptation of strain HV80. Another six amino acid substitutions in the S2 subunit of the recombinants showed that the Q855H mutation induced syncytium formation. A transient transfection assay demonstrated the S glycoprotein with the PRRR 690 /S motif at the S2′ cleavage site induced low-level cell–cell fusion, while H855Q substitution hindered cell–cell fusion and blocked cleavage event with S20 product. This study provides a basis for the construction of IBV recombinants capable of replicating in Vero cells, thus contributing to the advancement in the development of genetically engineered cell-based IBV vaccines. • S2 subunit mutations are associated with the strain HV80 Vero cell adaptation. • The RRRR 690 /S motif at the S2′ cleavage site triggers the infection. • The Q855H substitution enhances infection efficiency through cell-cell fusion. • The H855Q substitution also blocks the cleavage event with S20 product. [ABSTRACT FROM AUTHOR]

This study aims to evaluate whether different doses of Bacillus -based inoculum inoculated in chicken manure and sawdust composting will provide distinct effects on the co-regulation of ammonia (NH 3) and hydrogen sulfide (H 2 S), nutrient conversions and microbial topological structures. Results indicate that the Bacillus -based inoculum inhibits NH 3 emissions mainly by regulating bacterial communities, while promotes H 2 S emissions by regulating both bacterial and fungal communities. The inoculum only has a little effect on total organic carbon (TOC) and inhibits total sulfur (TS) and total phosphorus (TP) accumulations. Low dose inoculation inhibits total potassium (TK) accumulation, while high dose inoculation promotes TK accumulation and the opposite is true for total nitrogen (TN). The inoculation slightly affects the bacterial compositions, significantly alters the fungal compositions and increases the microbial cooperation, thus influencing the compost substances transformations. The microbial communities promote ammonium nitrogen (NH 4 +-N), TN, available phosphorus (AP), total potassium (TK) and TS, but inhibit nitrate nitrogen (NO 3 −-N), TP and TK. Additionally, the bacterial communities promote, while the fungal communities inhibit the nitrite nitrogen (NO 2 −-N) production. The core bacterial and fungal genera regulate NH 3 and H 2 S emissions through the secretions of metabolic enzymes and the promoting or inhibiting effects on NH 3 and H 2 S emissions are always opposite. Hence, Bacillus -based inoculum cannot regulate the NH 3 and H 2 S emissions simultaneously. [Display omitted] • The Bacillus -based inoculum inhibits NH 3 emissions, but promotes H 2 S emissions. • The inoculations alter the fungal compositions and increase microbial cooperation. • The core microbial genera regulate NH 3 and H 2 S emissions through metabolic enzymes. • Promoting or inhibiting effects of enzymes on NH 3 and H 2 S emissions are opposite. [ABSTRACT FROM AUTHOR]

Spray technology is an efficacious method to improve the indoor environments of poultry houses. In this study, two kind intensive enclosed poultry houses are sprayed with different spray additives in order to explore the effects and control mechanisms of spray processes on ammonia, particulate matters and aerosol bacterial compositions and investigate the fecal contributions to aerosol bacteria. The results show that the ammonia elimination rates through spray treatment by tap water (TP treatment), by EM microbial agent (EM treatment) or by glutaraldehyde-decamethonium bromide solution (HX treatment) are 67.0%, 85.4% and 96.9% in brood hen house and 60.7%, 76.0% and 94.8% in laying houses. The reductions of ammonia are mainly due to the decreased pH values caused by the increased Lactobacillus in chicken manure rather than the effects of aerosols after spraying. Spray processes reduce the contents of particulate matters while increase the proportions of PM10 and PM2.5 in TSP. The aerosol bacterial compositions after spraying alter mildly. Humidity is the main physicochemical factor leading to the variations of core bacteria in aerosols. The fecal transmission is the major source of aerosol bacteria in poultry houses and the spray processes merely present a relatively small impact on the fecal contribution to aerosol bacteria. The findings are conductive to optimize the breeding environment, enhance the ability of disease prevention and finally achieve the green and efficient cultivation. [Display omitted] • Spray with different additives removed air pollutants in poultry houses. • The increased Lactobacillus in chicken manure resulted in the reductions of ammonia. • Spray reduced particulate matters while increased the PM10 and PM2.5 proportions. • Spray hardly affected the fecal contribution to aerosol bacteria. [ABSTRACT FROM AUTHOR]

[Display omitted] • EM microbial agent and antibiotics had an antagonistic effect on TN retention. • EM microbial agent reduced the impacts of antibiotics on HS accumulation. • Firmicutes were associated with HS conversion. • Firmicutes, Actinobacteriota and Proteobacteria were related to nitrogen. This study aimed to investigate the independent and combined effects of antibiotic and EM microbial agent on the nitrogen and humus (HS) transformations as well as the bacterial community successions during the chicken manure and rice husk composting. EM microbial agent accelerated the oxytetracycline (OTC) degradation, but slowed down the norfloxacin (NOR) degradation. OTC inhibited the TN retention and promoted the HS accumulation, both NOR and EM microbial agent inhibited the TN retention and HS accumulation, while EM microbial agent showed an antagonistic effect on TN immobilization with antibiotics and reduced the impacts of antibiotics on HS. Obvious bacterial community successions occurred. Firmicutes were related to HS transformation, while Firmicutes , Actinobacteriota and Proteobacteria were associated with nitrogen conversion. NOR promoted the transformations of NH 4 +-N to NO 3 —-N and FA to HA. The findings provided theoretical data for the recycle of antibiotic-contaminated manure and the efficient production of high-quality compost. [ABSTRACT FROM AUTHOR]

Salmonella‐contaminated raw food is an important source of human food poisoning. Traditional methods for detecting Salmonella in meat involve many time‐consuming and laborious steps, preventing timely and effective control of the pathogen. In this study, a multiplex polymerase chain reaction (PCR) assay that targets serovar‐specific genes such as A7P63_0910 (Salmonella Indiana), sdfI (Salmonella Enteritidis), and STM4497 (Salmonella Typhimurium) for three meat‐associated Salmonella serovars was established. This multiplex PCR has been validated by extensive testing on reference strains and clinical isolates belonging to different Salmonella serovars (n = 348) and non‐Salmonella bacteria (n = 12). The detection limit is 100 CFU per reaction for bacterial culture, being equivalent to 10 pg per reaction for bacterial genomic DNA. Detection of Salmonella in raw meat samples by this multiplex PCR revealed that the prevalence of S. Indiana, S. Enteritidis, and S. Typhimurium is 7.7%, 5.7%, and 2.0%, respectively. The multiplex PCR established in this study can be used as a novel and convenient tool for simultaneous detection of three major meat‐associated Salmonella serovars, including the newly emerging and highly drug‐resistant S. Indiana. Practical applications: In this study, a multiplex polymerase chain reaction (PCR) assay that targets serovar‐specific genes such as A7P63_0910 (Salmonella Indiana), sdfI (Salmonella Enteritidis), and STM4497 (Salmonella Typhimurium) for three meat‐associated Salmonella serovars was established. This multiplex PCR is suitable for the simultaneous detection and differentiation of three major meat‐associated Salmonella serovars, and has been validated by extensive testing of reference strains and clinical isolates. The multiplex PCR assay can provide rapid and specific screening for top three Salmonella serovars in meat samples. [ABSTRACT FROM AUTHOR]