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Organic acids are crucial indicators of fruit flavor quality, but the metabolic characteristics and regulatory genes of organic acids during jujube fruit development remain largely unexplored. In this study, the cultivar 'Heigeda' with a high organic acid content was used as the experimental material. The organic acid content was quantified, and key candidate genes were identified through transcriptome analysis. The results indicated that malic acid and citric acid were the main organic acid content in jujube fruit and increased gradually with fruit development. Transcriptome analysis identified nine genes associated with malic acid and seven with citric acid, with four genes co-regulating malic acid and citric acid. Functional assays by transient overexpression and silencing of these four genes in the jujube fruits revealed that overexpression significantly upregulated the malic and citric acid content. However, only the silencing of aconitase1 (ZjACO1) and aconitase3 (ZjACO3) significantly downregulated the content of malic and citric acids. Therefore, aconitase1 (ZjACO1) and aconitase3 (ZjACO3) are considered the key genes that regulate the metabolism of citric acid and malic acid in jujube fruits. Our study can enrich the regulation mechanism of the organic acid metabolism of jujube fruit and provide theoretical support for the efficient cultivation of jujube fruit. [ABSTRACT FROM AUTHOR]

Soil mineral elements are the key factors affecting fruit quality, but which soil elements affect the sugars and organic acids of jujube fruit is still not clear. In this study, the fruit and soil of 18 major producing areas of the Tarim Basin were studied. By measuring the sugar and acid content in the fruits and element contents in the soil, the main soil mineral elements affecting the sugar and acid content in jujube fruits were identified. The results showed that the sugar components were mainly sucrose, glucose and fructose, and the organic acid components were mainly succinic acid, citric acid and malic acid. The fruits near the Kunlun Mountains had a higher ratio of sugar-to-acid and sweet-to-acid. Some elements in the soil of the Tarim Basin are abundant, such as the elements Ca, Fe, Mn and B, but the contents of the elements NO3-N, NH4-N, Zn and Mo are low. The contents of Ca, Mg and Mn were positively correlated with the contents of glucose, fructose and galactose. And the Fe, Ca, Mg and Mn were the main factors affecting the sugars and organic acid contents. Our study provides theoretical support for rational fertilization and efficient cultivation management of jujube. [ABSTRACT FROM AUTHOR]

Shiga toxin‐producing Escherichia coli (STEC) is an important food‐borne pathogen capable of causing severe gastrointestinal diseases in humans. Cattle and sheep are the natural reservoir hosts of STEC strains. Previously, we isolated 56 STEC strains from anal and carcass swab samples of cattle and sheep in farms and slaughterhouses. In this study, we performed whole‐genome sequencing of these isolates and determined their serotypes, virulence profiles, sequence types (STs) and genetic relationships. Our results showed that the 56 isolates belong to 20 different STs, 29 O:H serotypes and 8 stx subtype combinations. The highly prevalent serotypes for bovine and ovine isolates were O8:H25 and O87:H16, respectively. Five serotypes of cattle or sheep isolates are novel. The majority (63%) of cattle isolates contain stx1 + stx2, subtyped into stx1a, stx2a and stx2c. In contrast, most of the sheep isolates contain stx1 only, primarily subtyped into stx1a and stx1c. None of the isolates tested eae‐positive, but virulence factors such as ehxA and espP were present with variable prevalence rates. The prevalence of saa (19.6%) and espP (12.5%) in cattle isolates is much higher than that in sheep isolates, whereas that of subA (34%), katP (14.3%) and ireA (28.6%) in sheep isolates is considerably higher than that in cattle isolates. Core‐genome SNP analysis revealed that the majority of isolates could be clustered based on their serotypes or STs, whereas some clustering is associated with more than one ST or serotype. Five sheep isolates (4 belonging to ST675 and serotype O76:H19 and 1 belonging to ST25 and serotype O128:H2) share STs, serotypes and stx profiles with two hemolytic uremic syndrome–associated enterohemorrhagic E. coli (HUSEC) isolates; a cattle isolate belonging to the same ST as HUSEC isolate HUSEC001 contains all the nine virulence genes tested. These data suggest a potential of the six isolates for causing severe human infections. Collectively, we described the characteristics of cattle and sheep STEC isolates from Xinjiang, China, which may be utilized in comparative studies of other geographic regions and sources of isolation, and for surveillance as well. [ABSTRACT FROM AUTHOR]

[Objective] This study investigated antibiotic resistance and drug resistant gene profiles of Escherichia coli from retail livestock and chicken meat in Urumqi, Xinjiang to provide basis for prevention and control of resistance surveillance of meat products. [Method] E. coli was isolated from retail livestock and chicken meat samples in different regional fresh nineteen supermarkets in seven districts of Urumqi, including chicken (w = 90), pork (w = 90), beef (w = 84) and mutton (w=89). Those isolates were screened and isolated by McConkey medium and CHROMagar™ Orientation, and identified by specific 16S rDNA. The phylogenetic groups of isolates were analyzed using multiplex PCR, resistance of isolates was determined by K-B disk diffusion method, and corresponding resistant genes were amplified by PCR and sequenced. [Result] A total of 252 strains were isolated from 353 meat samples. The phylogenetic group analysis showed a domination by group A (79. 4%), followed by B1 (12. 3%). The resistance phenotypes test showed that those strains were highly resistant to tetracycline (49. 6%), ampicillin (41. 6%) and sulfame-thoxazole/tritnethopritn (30. 9%) and chloroatnphenicol (26. 6%), but were less resistant to atnikacin (1. 9%), polymyxin B (0. 8%) and ampicillin-sulbactam (0. 4%). The detection of drug resistance genes of tetA, blaTEM, cml1, aadAl, aac, sul1 and blaCTX-M were 90. 4%, 32. 1%, 31. 3%, 27. 4%, 14. 5%, 12. 8% and 9. 2%, respectively, whereas tetE, tetG, blaSHV were not detected. [Conclusion] The contamination of E. coli was serious in commercial livestock and chicken meat in Urumqi. More attention should be paid to retail meat, which plays an important role in spread of bacterial resistance. [ABSTRACT FROM AUTHOR]