Optimization of production process of Aeromonas veronii CA07 strain inactivated vaccine / 中国生物制品学杂志

@#Abstract：Objective To optimize the production process of inactivated vaccine of Aeromonas veronii（AV）CA07 strain. Methods The fermentation culture process of AV CA07 strain liquid was determined through the optimization of the culture time（2～16 h），medium（optimized fermentation medium，LB medium and NB medium）and fermentation conditions（in⁃ oculation amount of 1%，5%，10% and 15%；ventilation rate of 2，4，6 and 8 L／min and fermentation time of 6，8，10 and 12 h）. The optimal inactivation process was determined through the comparison of the final concentration of formalde⁃ hyde solution（0. 10%，0. 20%，0. 30% and 0. 40%），inactivation temperature（28 and 37 ℃）and inactivation time（24， 48 and 72 h）. The large⁃scale production process of inactivated vaccine of AV CA07 strain in 500 L fermentor was estab⁃ lished and the prepared vaccines were tested for safety and immunogenicity. Results The optimal inoculation amount of AV CA07 strain was 5%，ventilation rate was 4 L／min and culture time was 10 ~ 12 h. The optimal inactivation condition was adding formaldehyde solution with final concentration of 0. 30% incubating at 37 ℃ for 24 h. The number of viable bacteria in the fermentation broth of AV CA07 strain prepared in 500 L fermentor was more than 8 × 109 CFU／mL. All crucian carps immunized with the inactivated vaccine by abdomen survived. After challenge，the relative immune protection rate was more than 90%. Conclusion AV CA07 strain inactivated vaccine prepared by optimized production process showed good safety and immunogenicity.

Characterization and phylogenetic analysis of a Aeromonas veronii clinical strain isolated from blood culture / 中华微生物学和免疫学杂志

Objective To identify an unknown pathogenic strain (X1) isolated from blood culture of an inpatient and to conduct a phylogenetic analysis on it. Methods The X1 strain was isolated from blood culture of an inpatient in the Second Xiangya Hospital of Central South University in 2016. It was identified by morphology biochemical testing and 16S rRNA gene sequencing. Based on genetic distances, a phylogenetic tree was constructed to compare the X1 strain with its homologous species in GenBank in order to reveal its genetic evolution. Results The X1 strain was gram-negative. Biochemical testing for oxidase, glucose and V-P reaction were positive (+) , while the result of citrate was negative (-) . Sequence align-ment analysis of 16S rRNA showed that the X1 strain (1466 bp) was highly homologous with Aeromonas veronii X71120. 1 with a similarity of more than 99％. Genetic distances between the X1 strain and its ho-mologous species, including Aeromonas veronii, Aeromonas hydrophila and Aeromonas sobria, were calculat-ed by MEGA5. 0 and the results revealed that the genetic distance (0. 014) between it and Aeromonas veronii X71120. 1 was the shortest, but the subspecies of it was unable to identify. Cluster analysis also indicated that the X1 strain and Aeromonas veronii were clustered to a small branch. Conclusions The X1 isolate was an Aeromonas veronii strain. Besides, Aeromonas veronii and Aeromonas sobria were similar in genetic char-acteristics.

Isolation and Identification of a Potential Amylolytic Probiotic Bacterium from the Gut of Jundiá Catfish, Rhamdia quelen

ABSTRACT This study aimed to isolate a potential probiotic amylolytic strain from the gut of jundiá catfish to improve carbohydrate digestibility in fish. Two of 31 strains isolated from the foregut of Rhamdia quelen were able to grow on starch-agar medium and were considered amylolytic. The strain that presented higher amylolytic potential, based on a qualitative amylase assay, was chosen. The strain was phenotypically characterized and analysed to determine bile and pH tolerance and extracellular quantitative amylase activity. The probiotic candidate, identified as Aeromonas veronii, showed the ability to survive stresses from a range of pH and bile salt conditions and secreted an interesting enzymatic profile, which may exhibit a synergistic effect when combined with the enzymes secreted by the jundiá catfish, improving carbohydrate digestion in the host. The results demonstrated the potential of A. veronii to improve the digestion process in jundiá by providing exogenous enzymes for the breakdown and absorption of nutrients.

Identification of a pathogenic Aeromonas veronii isolated from rock carp, Procypris rabaudi / 中国人兽共患病学报

In June 2016,a disease among the cultured rock carp (Procypris rabaudi) in Yongchuan of Chongqing Municipality occurred.The aim of this study was to investigate biological characteristics and provide reference for Aeromonas veronii identification diagnosis and treatment.Pathogenic bacteria strain YY01 from the dying fishes were examined and isolated.Strain YY01's taxonomic status was identified by observing the morphology,studying the physiological and biochemical characters and sequencing the 16S rRNA and housekeeping gene gyrB.Its pathogenicity was checked by artificial infection experiment and virulence genes.Furthermore,effective medicine was detected by drug sensitivity.The 16S rRNA and gyrB gene sequence of the strain YY01 was more than 99％ homology with that of Aeromonas veronii,suggesting that the pathogen was Aeromonas veronii,which was also identified by the results of biochemical analysis.The LD50 of strain YY01 to rcok carp was 5.06 × 104 CFU/g.Four virulence genes were detected from YY01,including aerolysin (aer),hemolysin (Hly),Outer Membrane Protein Gene A (OmpA) and adhesion (Aha) genes.Antibiotic sensitivity assays showed that among 40 antibiotics tested,22 were sensitive and 11 were resistant.In conclusion,the strain YY01 is identified as Aeromonas veronii and it is proved to have strong pathogenicity.

Characterization of pathogenic Aeromonas veronii bv. veronii associated with ulcerative syndrome from Chinese longsnout catfish (Leiocassis longirostris Günther)

273 bacterial strains were isolated from 20 Chinese longsnout catfish samples. The biochemical characteristics of all strains conformed to the species description of Aeromonas veronii bv. veronii on the basis of Vitek GNI+ card. Furthermore, 16S rDNA, gyrB and rpoD sequences of the representative strain PY50 were sequenced and showed high similarity with A. veronii bv. veronii in Genbank. Antibiotic-resistance of the representative strain PY50 was assessed by the Kirby-Bauer disk diffusion method, and the results showed it was susceptible and moderately susceptible to 13 and 4 of the 21 antimicrobial agents tested. Extracellular products of strain PY50 contained gelatinase, lecithinase, elastase, most of lipase and lipopolysaccharide. Virulence of strain PY50 and extracellular products to Chinese longsnout catfish were also tested, and LD50 were about 3.47~10(4) CFU per fish and 11.22 ƒÊg per fish in intraperitoneal injection respectively. This is the first report that A. veronii bv. veronii was the pathogenic agent of ulcerative syndrome in Chinese longsnout catfish.

Different Clinical Characteristics Among Aeromonas hydrophila, Aeromonas veronii biovar sobria and Aeromonas caviae Monomicrobial Bacteremia

This study aimed to compare the clinical presentations of Aeromonas hydrophila, A. veronii biovar sobria and A. caviae monomicrobial bacteremia by a retrospective method at three hospitals in Taiwan during an 8-yr period. There were 87 patients with A. hydrophila bacteremia, 45 with A. veronii biovar sobria bacteremia and 22 with A. caviae bacteremia. Compared with A. hydrophila and A. veronii biovar sobria bacteremia, A. caviae bacteremia was more healthcare-associated (45 vs 30 and 16%; P = 0.031). The patients with A. caviae bacteremias were less likely to have liver cirrhosis (27 vs 62 and 64%; P = 0.007) and severe complications such as shock (9 vs 40 and 47%; P = 0.009) and thrombocytopenia (45 vs 67 and 87%; P = 0.002). The APACHE II score was the most important risk factor of Aeromonas bacteremia-associated mortalities. The APACHE II scores of A. caviae bacteremias were lower than A. hydrophila bacteremia and A. veronii biovar sobria bacteremia (7 vs 14 and 16 points; P = 0.002). In conclusion, the clinical presentation of A. caviae bacteremia was much different from A. hydrophila and A. veronii biovar sobria bacteremia. The severity and mortality of A. caviae bacteremia were lower than A. hydrophila or A. veronii biovar sobria bacteremia.

Misidentification as Vibrio alginolyticus with Vitek GNI+ Card in Three Cases / 대한임상미생물학회지

The introduction of a new, fully automated system into the clinical microbiology laboratory contributes to a rapid identification of microorganisms with accurate and reliable results, but such a system requires a high cost and additional tests for identification of some species. For instance, additional tests on oxidase, indole, motility, hemolysis, and pigmentation are needed in the correct identification by using Vitek GNI+ system (bioMerieux Vitek Inc., MO, USA). In particular, Vibrio and Aeromonas species are occasionally identified incorrectly when an automated system is used, and thus conventional biochemical tests may be more reliable in the identification of such species. We experienced three cases of incorrect identification of Vibrio parahaemolyticus, Vibrio cholerae, and Aeromonas veronii biovar sobria as Vibrio alginolyticus by using Vitek GNI+ card.