Transcriptome analysis of Acinetobacter calcoaceticus HX09 strain with outstanding crude-oil-degrading ability.

Microbial remediation plays a pivotal role in the elimination of petroleum pollutants, making it imperative to investigate the capabilities of microorganisms in degrading petroleum. The present study describes the isolation of a promising strain, Acinetobacter sp. HX09, from petroleum-contaminated water. GC-MS analysis revealed a remarkable removal efficiency for short and medium-chain alkanes, with a rate of approximately 64% after a 7-days incubation at 30 °C. Transcriptome analysis of HX09 exhibited a predominant upregulation in gene expression levels by the induce of crude oil. Notably, genes such as alkane 1-monooxygenase, dehydrogenases and fatty acid metabolic enzymes exhibited fold changes range from 3.16 to 1.3. Based on the alkB gene sequences in HX09, the Phyre2 algorithm generated a three-dimensional structure that exhibited similarity to segments of acyl coenzyme desaturases and acyl lipid desaturases. Furthermore, three biodegradation-related gene clusters were predicted in HX09 based on the reference genome sequence. These findings contribute to our understanding of the hydrocarbon-degrading mechanisms employed by Acinetobacter species and facilitate the development of effective remediation strategies for crude oil- polluted environments.

The role of the genetic elements bla oxa and IS Aba 1 in the Acinetobacter calcoaceticus-Acinetobacter baumannii complex in carbapenem resistance in the hospital setting.

INTRODUCTION: Members of the Acinetobacter genus are key pathogens that cause healthcare-associated infections, and they tend to spread and develop new antibiotic resistance mechanisms. Oxacillinases are primarily responsible for resistance to carbapenem antibiotics. Higher rates of carbapenem hydrolysis might be ascribed to insertion sequences, such as the ISAba1 sequence, near bla OXA genes. The present study examined the occurrence of the genetic elements bla OXA and ISAba1 and their relationship with susceptibility to carbapenems in clinical isolates of the Acinetobacter calcoaceticus-Acinetobacter baumannii complex. METHODS: Isolates identified over 6 consecutive years in a general hospital in Joinville, Southern Brazil, were evaluated. The investigation of 5 families of genes encoding oxacillinases and the ISAba1 sequence location relative to bla OXA genes was conducted using polymerase chain reaction. RESULTS: All isolates presented the bla OXA-51-like gene (n = 78), and 91% tested positive for the bla OXA-23-like gene (n = 71). The presence of ISAba1 was exclusively detected in isolates carrying the bla OXA-23-like gene. All isolates in which ISAba1 was found upstream of the bla OXA-23-like gene (n = 69) showed resistance to carbapenems, whereas the only isolate in which ISAba1 was not located near the bla OXA-23-like gene was susceptible to carbapenems. The ISAba1 sequence position of another bla OXA-23-like-positive isolate was inconclusive. The isolates exclusively carrying the bla OXA-51-like gene (n = 7) showed susceptibility to carbapenems. CONCLUSIONS: The presence of the ISAba1 sequence upstream of the bla OXA-23-like gene was strongly associated with carbapenem resistance in isolates of the A. calcoaceticus-A. baumannii complex in the hospital center studied.

The role of the genetic elements bla oxa and IS Aba 1 in the Acinetobacter calcoaceticus-Acinetobacter baumannii complex in carbapenem resistance in the hospital setting

Abstract: INTRODUCTION: Members of the Acinetobacter genus are key pathogens that cause healthcare-associated infections, and they tend to spread and develop new antibiotic resistance mechanisms. Oxacillinases are primarily responsible for resistance to carbapenem antibiotics. Higher rates of carbapenem hydrolysis might be ascribed to insertion sequences, such as the ISAba1 sequence, near bla OXA genes. The present study examined the occurrence of the genetic elements bla OXA and ISAba1 and their relationship with susceptibility to carbapenems in clinical isolates of the Acinetobacter calcoaceticus-Acinetobacter baumannii complex. METHODS: Isolates identified over 6 consecutive years in a general hospital in Joinville, Southern Brazil, were evaluated. The investigation of 5 families of genes encoding oxacillinases and the ISAba1 sequence location relative to bla OXA genes was conducted using polymerase chain reaction. RESULTS: All isolates presented the bla OXA-51-like gene (n = 78), and 91% tested positive for the bla OXA-23-like gene (n = 71). The presence of ISAba1 was exclusively detected in isolates carrying the bla OXA-23-like gene. All isolates in which ISAba1 was found upstream of the bla OXA-23-like gene (n = 69) showed resistance to carbapenems, whereas the only isolate in which ISAba1 was not located near the bla OXA-23-like gene was susceptible to carbapenems. The ISAba1 sequence position of another bla OXA-23-like-positive isolate was inconclusive. The isolates exclusively carrying the bla OXA-51-like gene (n = 7) showed susceptibility to carbapenems. CONCLUSIONS: The presence of the ISAba1 sequence upstream of the bla OXA-23-like gene was strongly associated with carbapenem resistance in isolates of the A. calcoaceticus-A. baumannii complex in the hospital center studied.

Molecular identification of phosphate-solubilizing native bacteria isolated from the rhizosphere of Prosopis glandulosa in Mexicali valley.

One of the main limitations in intensive crop production in Northwestern Mexico is the dependence on the use of phosphate fertilizer. In this study, we isolated indigenous microorganisms with phosphate solubilization capacities from mesquite (Prosopis glandulosa) present in the Mexicali valley. In total, 4 bacteria were isolated from the rhizosphere of mesquite, including ICA01, ICA02Ba, ICA03Bs, and ICA04Ma. The bacterial isolates were identified based on their phenotypic and 16S rRNA gene sequencing data to be Acinetobacter calcoaceticus. The results showed that ICA01 was the most efficient in solubilizing phosphate, followed by ICA02Ba and ICA03Bs, while ICA04Ma showed the lowest phosphate-solubilizing activity. The pH value of the culture medium decreased with bacterial growth, suggesting that these strains produce organic acids that solubilize phosphorus. These results will be useful for biotechnological studies and A. calcoaceticus may be employed for biofertilization programs in northwest Mexico.

Caracterização molecular e fenotípica de amostras bacterianas pertencentes ao complexo Acinetobacter calcoaceticus-Acinetobacter baumannii / Molecular and phenotypic characterization of Acinetobacter calcoaceticus-Acinetobacter baumannii isolates

Nos últimos 30 anos, Acinetobacter tornou-se um dos patógenos de maior preocupação clínica pela falta de terapias eficazes em virtude do fenótipo de multirresistência frequentemente apresentado. Dentre as espécies do gênero Acinetobacter, A. baumannii, A. genoespécie 3 e A. genoespécie 13TU são as mais comumente encontradas a partir de amostras biológicas. Estas espécies ao lado de A. calcoaceticus constituem o complexo A. calcoaceticus-A. baumannii (ACB). Este estudo propõe um esquema composto de duas PCRs para a identificação das espécies de interesse médico que fazem parte do complexo ACB. O método é simples, rápido e, além de identificar as espécies, permite pesquisar a presença de genes de resistência. Foram identificadas 515 amostras do complexo ACB, isoladas de pacientes no período de janeiro de 2005 a dezembro de 2010. A identificação das espécies do complexo ACB foi realizada por esquema composto de duas reações de PCR. Foram avaliados os perfis de sensibilidade por disco difusão e a pesquisa da presença dos genes blaOXA-23-like, blaOXA-24-like, blaOXA-51-like, blaOXA-58-like, blaIMP, blaVIM, blaSIM, blaSPM e blaGIM foi realizada por PCR utilizando-se iniciadores específicos. No grupo de amostras estudas, 82,5% são A. baumannii (425), 11,5% A. genoespécie 13TU (59) e 6,0% A. genoespécie 3 (30), sendo A. baumannii mais isolado em pacientes internados em UTIs (p=0,0407) e A. genoespécie 13TU mais isolado em pacientes de outros ambientes hospitalares (p=0,0204). A. baumannii apresentou menor sensibilidade a todos os antimicrobianos quando comparado com A. genoespécie 13TU e A. genoespécie. 3 (p<0,05). Foi possível observar ao longo do período estudado o aumento significativo da resistência aos carbapenêmicos e da sensibilidade a gentamicina por A. baumannii entre os isolados de pacientes de UTIs (p<0.05). Nenhum dos genes codificadores para metalo-lactamases foi detectado nas amostras estudadas Dentre os cepas resistentes aos carbapenêmico...

The genus Acinetobacter has emerged as one of the most troublesome pathogens for health care institutions globally. Its clinical significance, especially over the last 15 years, has been driven by its remarkable ability to up regulate or acquire resistance determinants, making it one of the organisms threatening the current antibiotic era. A. baumannii, A. 3 and A. 13TU are the most commonly species found from biological samples. These species beside A. calcoaceticus are very closely related and difficult to distinguish from each other by phenotypic properties. Therefore, it has been proposed to refer to these species as the A.calcoaceticus-A. baumannii complex(ACB). In the period from 2005 to 2009, the most frequent bacterial isolates among the nosocomial infection at the HU-USP was ACB (18%). Due to the frequency with which species are involved in ACB outbreaks of infection in the HU-USP and the emergency clinic because of expression of the phenotype of resistance to several classes of antibiotics, this study aimed to identify and characterize the species of complex ACB by molecular methods, to study their mechanisms of resistance and to characterize the different clones from patients admitted to different hospital areas. Furthermore, the ability to characterize biofilm formation, adhesion to different cell lines as well as the mechanisms of cell-cell communication were analyzed. From the ACB complex, 515 samples were identified, isolated from patients from January 2005 to December 2010. The identification of clinical species of the ACB was performed by molecular methods that were developed and validated for identification of Acinetobacter sp. include two reactions of PCR. The profiles of sensibility were evaluated by disc diffusion and the detection of the presence of genes blaOXA-23-like, blaOXA-24-like, blaOXA-51-like, blaOXA-58-like, blaIMP, blaVIM, blaSIM, blaGIM, and blaSPM were performed using specific primers. Molecular typing was performed using...

The improvement of lipase secretion and stability by addition of inert compounds into Acinetobacter calcoaceticus cultures.

Acinetobacter calcoaceticus BD413 produces variable amounts of an exocellular lipase that becomes rapidly inactivated upon secretion. To achieve high yield and protect the enzyme, we assayed the addition of several inert compounds to cell-free supernatants, cell fractions, and whole cultures. Glass beads, poly(ethylene glycol) 600, Triton X-100, saccharose, gum arabic, and beta-cyclodextrin were among the compounds tested. beta-Cyclodextrin and gum arabic (and saccharose to a lesser extent) were effective enzyme stabilizers in cell-free supernatants, while gum arabic, glass beads, and Triton X-100 improved lipase secretion from cells, and, therefore, total lipase yield (30-50%, according to the additive). In whole cultures, beta-cyclodextrin was the most effective additive, particularly in combination with glass beads or gum arabic. Indeed, cultures containing beta-cyclodextrin plus gum arabic were able to maintain 95% (+/- 1.5%) of the initial lipase activity for more than 16 h, while control cultures with no additives maintained only 10% (+/- 4%) of the enzyme activity after the same period. In conclusion, the addition of inert compounds in cultures may be considered a useful approach for achieving increased yield and lipase stabilization, amenable for downstream processing.

The discriminatory power of ribo-PCR compared to conventional ribotyping for epidemiological purposes.

Molecular typing techniques have become increasingly important for confirmation of epidemiological relationships and delimitation of nosocomial outbreaks. The discriminatory power of the two DNA-based typing methods, conventional ribotyping and ribo-PCR, was assessed to distinguish between selected strains of Acinetobacter calcoaceticus, Enterobacter cloacae, Serratia marcescens and Pseudomonas aeruginosa. Overall, conventional ribotyping was more discriminatory than ribo-PCR.