Aeromonas Taiwanensis Research Articles

Isolation and Characterization of Aeromonas taiwanensis Strain for Simultaneous Production of Cellulase, Amylase, Pectinase, and Protease Enzymes

Isolation and Characterization of Aeromonas taiwanensis Strain for Simultaneous Production of Cellulase, Amylase, Pectinase, and Protease Enzymes

Aeromonas de tambaqui de cultivo do norte do Brasil: identificação molecular e potencial patogênico

ABSTRACT: The aim of this study was to molecularly identify different species of Aeromonas isolated from farmed tambaqui (Colossoma macropomum) from North Brazil, and evaluate their pathogenic potential by the presence of virulence genes. From the extraction of bacterial DNA, PCR (polymerase chain reaction) of the primers 16S rDNA, aerA (cytolytic enterotoxin), ast (cytotoxic enterotoxin) and act (cytotoxic enterotoxin) were performed. Of 24 isolates evaluated, eight amplified the ast gene, one amplified the act gene, but the areA gene was not amplified in any isolate. Sequencing of the 16S rRNA primer revealed a predominance of Aeromonas jandaei specie (92%). Aeromonas taiwanensis (4%), for the first time isolated from fish in Brazil, and Aeromonas hydrophila (4%) each appeared as just one isolate. Results showed that 32% of Aeromonas isolated from farmed tambaqui have considerable pathogenic potential for systemic damage, since the selected PCR primers are encoding the most common virulence genes in Aeromonas with high pathogenic intensity.

Screening and identification of azo dye decolorizers from mangrove rhizospheric soil.

Removal of synthetic textile dyes poses a challenge to the textile industry and a threat to the environment's flora and fauna. These dyes are recalcitrant and not very amenable to physical and chemical techniques of degradation. Hence, several studies on alternative bioremediation methods involving plants, plant roots, single microbes, or a consortium of microbes for the decolorization of dyes have been carried out. In the present study, potent bacteria for dye decolorization were isolated from rhizospheric soil of mangrove plants collected from Kamothe, Navi Mumbai, India. Of the 20 isolates obtained after enrichment, seven isolates were used for further screening of efficient decolorization ability in minimal basal media containing 10% glucose, 2.5% trace metal solution, and 0.1% of Methyl Orange (MO) dye concentration. Physiological parameters to optimize the decolorization of dye at optimum pH, temperature, and incubation time were studied for all the seven isolates. UV-vis and Fourier transform infrared spectroscopy were used to investigate dye decolorization. The seven isolates were characterized morphologically, biochemically, and molecular identification of these bacterial isolates was performed by 16S rRNA sequence analysis. The isolates were identified as Bacillus paramycoides, Pseudomonas taiwanensis, Citrobacter murliniae, Acinetobacter pitti, Exiguobacterium acetylicum, Psychrobacter celer, and Aeromonas taiwanensis. Out of these, Aeromonas taiwanensis has shown exceptional capacity by ~ 100% decolorization of azo dye in minimum time.

Microbiological Assessment of Irrigation Water That Serves as Watershed for Wastewater in Osogbo and Its Impact on Fresh Vegetables

This study was designed to investigate the microbiological safety of irrigation water along with waste effluents and their impact on vegetables. Irrigation water samples situated amongst hospital, abattoir and petrol station were aseptically collected with fresh vegetables simultaneously. Physicochemical, microbiological and molecular studies were carried out using standard methods. The result of the physicochemical analysis shows that the irrigation water samples temperature ranged from 23.4-24.8oC while the pH ranged from 7.24-7.51. The bacterial count of isolates showed that the water samples were highly contaminated with microbial count ranging from 9×102 to 151×104cfu/ml which has exceeded the WHO microbial count recommendation for potable water (10×103cfu/ml). Organisms isolated from both water and vegetable samples were all pathogenic. Antimicrobial susceptibility test results showed that all the isolates were susceptible to cefepime and oxacillin while 60% of the isolates were multidrug resistant. Aeromonas taiwanensis was recovered from both the water and vegetable samples. This however calls for huge attention as Aeromonas species are potential pathogenic organisms that can be isolated from both clinical and polluted environmental samples such as wounds, petrol and abattoir litters. Therefore, it can be concluded that wastewater effluents should not be channeled directly into surface water bodies without prior safety treatments.

Efficient degradation of ivermectin by newly isolated Aeromonas taiwanensis ZJB-18,044.

Ivermectin (IVM) is a widely used antiparasitic agent and acaricide. Despite its high efficiency against nematodes and arthropods, IVM may pose a threat to the environment due to its ecotoxcity. In this study, degradation of IVM by a newly isolated bacterium Aeromonas taiwanensis ZJB-18,044 was investigated. Strain ZJB-18,044 can completely degrade 50 mg/L IVM in 5 d with a biodegradation ability of 0.42 mg/L/h. Meanwhile, it exhibited high tolerance (50 mg/L) to doramectin, emamectin, rifampicin, and spiramycin. It can also efficiently degrade doramectin, emamectin, and spiramycin. The IVM degradation of strain ZJB-18,044 can be inhibited by erythromycin, azithromycin, spiramycin or rifampicin. However, supplement of carbonyl cyanide m-chlorophenylhydrazone, an uncoupler of oxidative phosphorylation, can partially recover the IVM degradation. Moreover, strain ZJB-18,044 cells can pump out excess IVM to maintain a low intracellular IVM concentration. Therefore, the IVM tolerance of strain ZJB-18,044 may be due to the regulation of the intracellular IVM concentration by the activated macrolide efflux pump(s). With the high IVM degradation efficiency, A. taiwanensis ZJB-18,044 may serve as a bioremediation agent for IVM and other macrolides in the environment.Electronic supplementary materialThe online version of this article (10.1007/s10532-020-09909-8) contains supplementary material, which is available to authorized users.

First report of isolation of Aeromonas taiwanensis from India.

Genus Aeromonas consists of facultative anaerobic, Gram negative Bacilli which are primary environmental inhabitants worldwide. A recently reported strain of the genus, Aeromonas taiwanensis, was found while studying the presence of infectious marine microbes in a lacustrine wetland in India, making this the first isolation report from the country.

Phylogenetic characteristics, virulence and antibiotic resistance of Aeromonas caviae isolated from foodborne and environmental samples

Objective To identify 49 Aeromonas caviae strains isolated form foodborne and environmental samples and analyze their virulence and antibiotic resistance. Methods All strains were identified by VITEK and API 20NE. Two housekeeping genes, gryB and rpoD, were amplified by PCR for phylogenetic analysis. Virulence genes including act, alt, ast, lip, ahp, aerA, hlyA, ompA1 and fla were detected by PCR. In vitro antimicrobial susceptibility of these strains was tested with AST-GN16 kit. Results Fifty-four Aeromonas caviae/Aeromonas hydrophila strains were identified by biochemical tests. Phylogenetic analysis revealed that there were 49 Aeromonas caviae strains, four Aeromonas hydrophila strains and one Aeromonas taiwanensis strain. The positive rates of alt, lip, ompA1, fla, act, aerA and hlyA genes were 100.00%, 100.00%, 79.59%, 14.29%, 2.04%, 2.04% and 2.04%, respectively. None of the isolates carried ast or ahp gene. A total of four virulence gene combination patterns were detected, and the predominant pattern was alt/lip/ompA1 (32/49). Antibiotic resistance rates of the Aeromonas caviae strains to ampicillin, cefazolin, cefoxitin, amoxicillin/clavulanic acid, ceftriaxone, trimethoprim/sulfamet hoxoazole and aztreonam were 79.59%, 14.29%, 10.20%, 6.12%, 4.08%, 4.08% and 2.04%, respectively. All strains were susceptible to piparacillin/tazobactam, imipenem, amikacin, gentamicin, levofloxacin, tigacycline and nitrofurantoin. Two multidrug-resistant strains were detected. Conclusions Aeromonas caviae/Aeromonas hydrophila can be effectively identified by the housekeeping genes gyrB and rpoD, and the closely related Aeromonas caviae and Aeromonas taiwanensis strains can be identified by rpoD. All Aeromonas caviae strains carried two or more virulence genes and one strain isolated from environment was positive for seven virulence genes. Aeromonas caviae strains were generally resistant to penicillin, which was mainly relate to the production of β-lactamase. No strain was resistant to carbapenems, aminoglycosides, fluoroquinolones, tetracyclines or furans. Multidrug-resistant strains were observed in food and drinking water. Key words: Aeromonas caviae; Aeromonas hydrophila; Phylogenetic analysis; gyrB gene; rpoD gene; Virulence gene; Antibiotic resistance

Low Cassette Variability in Class 2 and Class 1 Integrons of Aeromonas spp. Isolated from Environmental Samples

Integrons are prokaryotic genetic elements known to carry and exchange antibiotic resistance gene cassettes through a site-specific recombinase called integrase. In this work, 107 Aeromonas isolates from environmental origin, including fish, water, and sediments, were investigated for the presence of integrons. Using specific primers for Class 1, 2 and 3 integrases, only Class 1 and Class 2 integrons were detected. Detection of Class 2 integrases and their associated variable regions required two rounds of polymerase chain reaction (PCR). Sequencing of the intI2 amplicons confirmed them as integrase-derived products. Class 1 integrons were detected in 26 out of 107 isolates. PCR amplification of the variable regions associated to these integrons revealed an outstanding homogeneity, 25 of them having variable regions with an identical dfrA12-orfF-aadA2 cassette array and one integron carrying only the dfrA16 cassette. To assess clone diversity, chromosomal DNA from isolates was subjected to enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR), which discarded clonality in all instances. Class 2 integrons were surprisingly more prevalent than Class1 integrons, being detected in 60 out of 107 isolates. Forty-six of them showed a unique ERIC profile, while the remaining 14 strains displayed profiles that could be grouped in five different patterns. Cassette arrangements of all Class 2 variable regions were those described as the most prevalent (dfrA1-sat2-aadA1). A rather startling result of this work is the sensitivity to trimethoprim, streptomycin, and streptothricin of most strains, despite the presence of the cognate resistance genes. To know the integron distribution in environmental Aeromonas species, a phylogenetic reconstruction was done using rpoD/gyrB or rpoD/gyrA gene sequences. Isolates bearing these elements corresponded to Aeromonas hydrophila, Aeromonas veronii, Aeromonas salmonicida, Aeromonas dhakensis, Aeromonas sanarellii, Aeromonas taiwanensis, Aeromonas media, Aeromonas caviae, Aeromonas jandaei, and Aeromonas sp. This work revealed an unusual high incidence of Class 2 integrons and a low variability of cassette arrangements in environmental Aeromonas species.

Characterisation of Pb-resistant plant growth-promoting rhizobacteria (PGPR) from Scirpus grossus

Abstract Microorganisms that have the potential to improve plant productivity and health are known as plant growth-promoting rhizobacteria. Rhizobacteria play a major role in phytoremediation process by increasing the phytoremediation efficiency, thus the need to identify the superior rhizosphere bacteria has been gaining serious attention. In the current study, Scirpus grossus were exposed to a series of lead-contaminated sand (50, 100, 150, 200 and 300 mg/L) in plastic crates in greenhouse enviroment. Four weeks after exposure, the plants could sustain with toxicity of lead contamination by as much as 300 mg/L. Twenty two colonies of rhizobacteria were isolated from plant roots of Scirpus grossus. The rhizobacteria were characterised based on cell and colony observation. Identification of rhizobacteria was carried out based on analysis of 16S rDNA sequences and were identified as Aeromonas taiwanensis isolate 5E, Bacillus sp. Isolate 7G, Bacillus cereus isolate 8H and 3C , Bacillus velezensis isolate 9I, Bacillus proteolyticus isolate 4D, Bacillus stratosphericus isolate 14N, Bacillus megaterium isolate 11K , Pseudomonas sp. Isolate 12L , Enterobacter cloacae isolate 13M and isolate 16P, Bacillus aerius isolate 15O and Lysinibacillus sp. isolate 10J. The highly lead-resistant rhizobacteria were identified as Bacillus proteolyticus isolate 4D, Bacillus velezensis isolate 9I and Lysinibacillus sp. isolate 10J , which can tolerate against high concentration of lead (300 mg/L). The results showed that these highly lead-resistant rhizobacteria have potential to produce plant growth-promoting traits and have a ability to help S. grossus growth and productivity.

Emergence and Characterization of a Novel IncP-6 Plasmid Harboring bla KPC-2 and qnrS2 Genes in Aeromonas taiwanensis Isolates.

The dissemination of Klebsiella pneumoniae carbapenemases (KPCs) among Gram-negative bacteria is an important threat to global health. However, KPC-producing bacteria from environmental samples are rarely reported. This study aimed to elucidate the underlying resistance mechanisms of three carbapenem-resistant Aeromonas taiwanensis isolates recovered from river sediment samples. Pulsed-field gel electrophoresis (PFGE) and whole genome sequencing (WGS) analysis indicated a close evolutionary relationship among A. taiwanensis isolates. S1-PFGE, Southern blot and conjugation assays confirmed the presence of blaKPC–2 and qnrS2 genes on a non-conjugative plasmid in these isolates. Plasmid analysis further showed that pKPC-1713 is an IncP-6 plasmid with a length of 53,205 bp, which can be transformed into DH5α strain and mediated carbapenems and quinolones resistance. The plasmid backbone of p1713-KPC demonstrated 99% sequence identity to that of IncP-6-type plasmid pKPC-cd17 from Aeromonas spp. and IncP-6-type plasmid: 1 from Citrobacter freundii at 74% coverage. A 14,808 bp insertion sequence was observed between merT gene and hypothetical protein in p1713-KPC, which include the quinolone resistance qnrS2 gene. Emergence of plasmid-borned blaKPC and qnrS2 genes from A. taiwanensis isolates highlights their possible dissemination into the environment. Therefore, potential detection of such plasmids from clinical isolates should be closely monitored.

Rhizosphere of water hyacinth as a niche for multidrug resistant Aeromonas taiwanensis and Paenibacillus taiwanensis: A study from a tropical wetland of South India

The present study highlights the prevalence of multidrug resistant bacteria in the rhizosphere of a floating nuisant weed, water hyacinth growing in a tropical wetland of South India. The isolated strains from the rhizosphere were subjected to 16S rRNA gene sequence analysis and identified as Aeromonas taiwanensis and Paenibacillus taiwanensis. The identified strains were tested for the multidrug (13 antibiotics) resistance and pathogenicity. Both A. taiwanensis and P. taiwanensis were found to be multidrug resistant and only A.taiwanensis showed the pathogenicity. The present study is the first report on the prevalence of A. taiwanensis and P. taiwanensis in the rhizosphere of water hyacinth.

Microbiome of Pacific Whiteleg shrimp reveals differential bacterial community composition between Wild, Aquacultured and AHPND/EMS outbreak conditions

Crustaceans form the second largest subphylum on Earth, which includes Litopeneaus vannamei (Pacific whiteleg shrimp), one of the most cultured shrimp worldwide. Despite efforts to study the shrimp microbiota, little is known about it from shrimp obtained from the open sea and the role that aquaculture plays in microbiota remodeling. Here, the microbiota from the hepatopancreas and intestine of wild type (wt) and aquacultured whiteleg shrimp and pond sediment from hatcheries were characterized using sequencing of seven hypervariable regions of the 16S rRNA gene. Cultured shrimp with AHPND/EMS disease symptoms were also included. We found that (i) microbiota and their predicted metagenomic functions were different between wt and cultured shrimp; (ii) independent of the shrimp source, the microbiota of the hepatopancreas and intestine was different; (iii) the microbial diversity between the sediment and intestines of cultured shrimp was similar; and (iv) associated to an early development of AHPND/EMS disease, we found changes in the microbiome and the appearance of disease-specific bacteria. Notably, under cultured conditions, we identified bacterial taxa enriched in healthy shrimp, such as Faecalibacterium prausnitzii and Pantoea agglomerans, and communities enriched in diseased shrimp, such as Aeromonas taiwanensis, Simiduia agarivorans and Photobacterium angustum.

Pathogenic features of heterotrophic plate count bacteria from drinking-water boreholes.

Evidence suggests that heterotrophic plate count (HPC) bacteria may be hazardous to humans with weakened health. We investigated the pathogenic potential of HPC bacteria from untreated borehole water, consumed by humans, for: their haemolytic properties, the production of extracellular enzymes such as DNase, proteinase, lipase, lecithinase, hyaluronidase and chondroitinase, the effect simulated gastric fluid has on their survival, as well as the bacteria's antibiotic-susceptible profile. HuTu-80 cells acted as model for the human intestine and were exposed to the HPC isolates to determine their effects on the viability of the cells. Several HPC isolates were α- or β-haemolytic, produced two or more extracellular enzymes, survived the SGF treatment, and showed resistance against selected antibiotics. The isolates were also harmful to the human intestinal cells to varying degrees. A novel pathogen score was calculated for each isolate. Bacillus cereus had the highest pathogen index: the pathogenicity of the other bacteria declined as follows: Aeromonas taiwanensis > Aeromonas hydrophila > Bacillus thuringiensis > Alcaligenes faecalis > Pseudomonas sp. > Bacillus pumilus > Brevibacillus sp. > Bacillus subtilis > Bacillus sp. These results demonstrated that the prevailing standards for HPCs in drinking water may expose humans with compromised immune systems to undue risk.

Chironomid egg masses harbour the clinical speciesAeromonas taiwanensisandAeromonas sanarellii

Bacteria of the genus Aeromonas are found worldwide in aquatic environments and may produce human infections. In 2010, two new clinical species, Aeromonas sanarellii and Aeromonas taiwanensis, were described on the basis of one strain recovered from wounds of hospitalized patients in Taiwan. So far, only four environmental isolates of A.sanarellii and one of A.taiwanensis have been recorded from waste water in Portugal and an additional clinical strain of A.taiwanensis from the faeces of a patient with diarrhoea in Israel. In the present study, strains belonging to these two species were identified from chironomid egg masses from the same area in Israel by sequencing the rpoD gene. This represents a new environmental habitat for these novel species. The first data on the virulence genes and antibiotic susceptibility are provided. The isolates of these two new species possess multiple virulence genes and are sensitive to amikacin, aztreonam, cefepime, cefoxatime, ceftazidime, ciprofloxacin, gentamicin, piperacillin-tazobactam, tigecycline, tobramycin, trimethoprim-sulfamethoxazole and imipenem. The key phenotypic tests for the differentiation of these new species from their closest relative Aeromonas caviae included the utilization of citrate, growth at 45°C in sheep blood agar and acid production of cellobiose.

A Molecular Study on the Prevalence and Virulence Potential of Aeromonas spp. Recovered from Patients Suffering from Diarrhea in Israel

BackgroundSpecies of the genus Aeromonas are native inhabitants of aquatic environments and have recently been considered emerging human pathogens. Although the gastrointestinal tract is by far the most common anatomic site from which aeromonads are recovered, their role as etiologic agents of bacterial diarrhea is still disputed. Aeromonas-associated diarrhea is a phenomenon occurring worldwide; however, the exact prevalence of Aeromonas infections on a global scale is unknown.Methodology/Principal FindingsThe prevalence and virulence potential of Aeromonas in patients suffering from diarrhea in Israel was studied using molecular methods. 1,033 diarrheal stools were sampled between April and September 2010 and Aeromonas species were identified in 17 (∼2%) patients by sequencing the rpoD gene. Aeromonas species identity and abundance was: A. caviae (65%), A. veronii (29%) and Aeromonas taiwanensis (6%). This is the first clinical record of A. taiwanensis as a diarrheal causative since its recent discovery from a wound infection in a patient in Taiwan. Most of the patients (77%) from which Aeromonas species were isolated were negative for any other pathogens. The patients ranged from 1 to 92 years in age. Aeromonas isolates were found to possess different virulence-associated genes: ahpB (88%), pla/lip/lipH3/apl-1 (71%), act/hlyA/aerA (35%), alt (18%), ast (6%), fla (65%), lafA (41%), TTSS ascV (12%), TTSS ascF-ascG (12%), TTSS-dependent ADP-ribosylating toxins aexU (41%) and aexT (6%) in various combinations. Most of the identified strains were resistant to beta-lactam antibiotics but susceptible to third-generation cephalosporin antibiotics.Conclusions Aeromonas may be a causative agent of diarrhea in patients in Israel and therefore should be included in routine bacteriological screenings.

Aeromonas taiwanensis sp. nov. and Aeromonas sanarellii sp. nov., clinical species from Taiwan

Two clinical Aeromonas strains (A2-50(T) and A2-67(T)) recovered from the wounds of two patients in Taiwan could not be assigned to any known species of this genus based on their 16S rRNA gene sequences, which showed similarities of 99.6-99.8 % to those of the type strains of Aeromonas caviae, A. trota and A. aquariorum. The rpoD phylogenetic tree allocated these strains to two novel and independent phylogenetic lines, the neighbouring species being A. caviae, the type strain of which showed 93.2 % similarity (56 bp differences) to strain A2-50(T) and 92.2 % (63 bp differences) to strain A2-67(T). A multilocus phylogenetic analysis of five housekeeping genes (gyrB, rpoD, recA, dnaJ and gyrA; 3684 bp) confirmed that the two strains formed independent phylogenetic lineages within the genus. These data, together with phenotypic characterization and DNA-DNA reassociation results, revealed that these strains represent novel Aeromonas species, for which the names Aeromonas taiwanensis sp. nov. (type strain A2-50(T) =CECT 7403(T) =LMG 24683(T)) and Aeromonas sanarellii sp. nov. (type strain A2-67(T) =CECT 7402(T) =LMG 24682(T)) are proposed.