RESUMO
Forty-six Aeromonas spp. strains were isolated from fresh fish and investigated for their antimicrobial susceptibility, detection of Class 1 integrons by PCR, and arrangement of gene cassettes. Selected isolates were further characterized by enterobacterial repetitive intergenic consensus-PCR. Twenty isolates were found to carry Class 1 integrons. Amplification of the variable regions of the integrons revealed diverse bands ranging in size from 150 to 1,958 pb. Sequence analysis of the variable regions revealed the presence of several gene cassettes, such as adenylyl transferases (aadA2 and aadA5), dihydrofolate reductases (dfrA17 and dfrA1), chloramphenicol acetyl transferase (catB3), ß-lactamase (oxa2), lincosamide nucleotidil transferase (linF), aminoglycoside-modifying enzyme (apha15), and oxacillinase (bla OXA-10). Two open reading frames with an unknown function were identified as orfC and orfD. The aadA2 cassette was the most common integron found in this study. Interestingly, five integrons were detected in the plasmids that might be involved in the transfer of resistance genes to other bacteria. This is a first report of cassette encoding for lincosamides (linF) resistance in Aeromonas spp. Implications on the incidence of integrons in isolates of Aeromonas spp. from fresh fish for human consumption, and its possible consequences to human health are discussed.
Assuntos
Aeromonas/efeitos dos fármacos , Aeromonas/genética , Carpas/microbiologia , Farmacorresistência Bacteriana , Integrons , Aeromonas/isolamento & purificação , Animais , Antibacterianos/farmacologia , Ordem dos Genes , Genes Bacterianos , Testes de Sensibilidade Microbiana , Reação em Cadeia da Polimerase , Análise de Sequência de DNARESUMO
A novel haloalkaliphilic archaeon, strain B23(T) was isolated from the former lake Texcoco in Mexico. The strain was Gram-stain-negative, the cells coccoid to ovoid rods, red pigmented and aerobic. Strain B23(T) grew in 1.7-4.3 M NaCl, at pH 6.5-9.5 and at 25-45 °C with optimal growth at 2.6-3.4 M NaCl, pH 7.5-8.5 and 37 °C. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain B23(T) was most closely related to Natronobacterium gregoryi SP2(T) with 97.3â% sequence similarity. The polar lipids of strain B23(T) were phosphatidylglycerol and several unidentified phospholipids. The G+C content of the DNA of the strain was 62.5 mol%. Levels of DNA-DNA relatedness between strain B23(T) and Natronobacterium gregoryi DSM 3393(T) was 32.3â%. The name Natronobacterium texcoconense sp. nov. is proposed. The type strain is B23(T) (â=âCECT 8068(T)â=âJCM 17655(T)).
Assuntos
Natronobacterium/classificação , Filogenia , Microbiologia do Solo , Composição de Bases , DNA Arqueal/genética , Concentração de Íons de Hidrogênio , Lagos , México , Dados de Sequência Molecular , Natronobacterium/genética , Natronobacterium/isolamento & purificação , Hibridização de Ácido Nucleico , Fosfolipídeos/química , RNA Ribossômico 16S/genética , SalinidadeRESUMO
A novel Gram-positive, rod-shaped, spore-forming bacterium, designated 13CC(T) was isolated from soil of the former lake Texcoco. The strain was aerobic, catalase-positive and oxidase-negative. It grew at salinities of 0-26% (w/v) NaCl with an optimum at 9-16% (w/v) NaCl. The cells contain peptidoglycan type A1γ, A1γ' with glycine instead of l-alanine and three variations of peptidoglycan type A4γ. The only quinone detected was MK-7. The major fatty acid was anteiso-C(15:0). The polar lipids fraction consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and three different phospholipids. The DNA G+C content was 37.5 mol%. Maximum-likelihood phylogenetic analysis based on 16S rRNA gene sequences revealed that strain 13CC(T) was closely related to members of the genus Bacillus and shared 92.35% similarity with Bacillus agaradhaerens, 92.28% with Bacillus neizhouensis and 92.21% with Bacillus locisalis. It is proposed based on the phenotypic, genotypic and phylogenetic analyses that the novel isolate should be classified as a representative of a new genus and novel species, for which the name Texcoconibacillus texcoconensis gen. nov., sp. nov. is proposed. The type strain of Texcoconibacillus texcoconensis is 13CC(T) (â=JCM 17654(T)â=DSM 24696(T)).
Assuntos
Bacillus/classificação , Lagos/microbiologia , Filogenia , Microbiologia do Solo , Bacillus/genética , Bacillus/isolamento & purificação , Técnicas de Tipagem Bacteriana , Composição de Bases , DNA Bacteriano/genética , DNA Ribossômico/genética , Ácidos Graxos/análise , México , Dados de Sequência Molecular , Peptidoglicano , Fosfolipídeos/análise , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Vitamina K 2/análogos & derivados , Vitamina K 2/análiseRESUMO
A new haloalkaliphilic archaeon, strain B4(T), was isolated from the former lake Texcoco in Mexico. The cells were Gram-negative, pleomorphic-shaped, pink to red pigmented and aerobic. Strain B4(T) required at least 2.5 M NaCl for growth, with optimum growth at 3.4 M NaCl. It was able to grow over a pH range of 7.5-10.0 and temperature of 25-50 °C, with optimal growth at pH 9 and 37 °C. Cells are lysed in hypotonic treatment with less than 1.3 M NaCl. The major polar lipids of strain B4(T) were phosphatidylglycerol and methyl-phosphatidylglycerophosphate. Phospholipids were detected, but not glycolipids. The nucleotide sequence of the 16S rRNA gene revealed that the strain B4(T) was phylogenetically related to members of the genus Natronorubrum. Sequence similarity with Natronorubrum tibetense was 96.28 %, with Natronorubrum sulfidifaciens 95.06 % and Natronorubrum sediminis 94.98 %. The G+C content of the DNA was 63.3 mol%. The name of Natronorubrum texcoconense sp. nov. is proposed. The type strain is B4(T) (=CECT 8067(T) = JCM 17497(T)).