Calcoaceticus Research Articles

Antimicrobial Effect of Medicinal Plants on Microbiological Quality of Grape Juice

Abstract The safety of plant-based food of plant origin is a priority for producers and consumers. The biological value of food products enriched with herbal ingredients is getting more popular among consumers. The present study was aimed to evaluate microbiological quality of grape juice enriched with medicinal plants. There were two varieties of grapes -Welschriesling and Cabernet Sauvignon and six species of medicinal plants used for the experiment: Calendula officinalis L., Ginkgo biloba, Thymus serpyllum, Matricaria recutita, Salvia officinalis L., and Mentha aquatica var. citrata. A total of 14 samples of juice were prepared and two of them were used as controls and 12 samples were treated with medicinal plants. Total microbial count, coliforms, lactic acid bacteria and yeasts and microscopic fungi for testing the microbiological quality were detected. All the samples were negative for lactic acid bacteria. There were neither coliform bacteria nor yeast and fibrous microscopic fungi present in some of the treated samples apart from the control samples. Coliform bacteria of 1 log cfu/mL were detected during the first testing and identified Proteus vulgaris in the control sample of grape juice of the variety Welschriesling. The yeast of the genus Candida was present in 2 log cfu/mL and it was detected during first and second testing in the control sample of Cabernet Sauvignon, unlike the other samples. The sample of grape juice with the addition of sage had the most significant inhibitory effect on total count of bacteria. The most common microorganisms in all samples were Bacillus cereus and Acinetobacter johnsonii, however, those microorganisms were absent during second testing due to the action of naturally occurring antimicrobials in the grapes.

Use of Shotgun Metagenomics and Metabolomics to Evaluate the Impact of Glyphosate or Roundup MON 52276 on the Gut Microbiota and Serum Metabolome of Sprague-Dawley Rats.

Background:There is intense debate on whether glyphosate can inhibit the shikimate pathway of gastrointestinal microorganisms, with potential health implications.Objectives:We tested whether glyphosate or its representative EU herbicide formulation Roundup MON 52276 affects the rat gut microbiome.Methods:We combined cecal microbiome shotgun metagenomics with serum and cecum metabolomics to assess the effects of glyphosate [0.5, 50, ] or MON 52276 at the same glyphosate-equivalent doses, in a 90-d toxicity test in rats.Results:Glyphosate and MON 52276 treatment resulted in ceca accumulation of shikimic acid and 3-dehydroshikimic acid, suggesting inhibition of 5-enolpyruvylshikimate-3-phosphate synthase of the shikimate pathway in the gut microbiome. Cysteinylglycine, , and valylglycine levels were elevated in the cecal microbiome following glyphosate and MON 52276 treatments. Altered cecum metabolites were not differentially expressed in serum, suggesting that the glyphosate and MON 52276 impact on gut microbial metabolism had limited consequences on physiological biochemistry. Serum metabolites differentially expressed with glyphosate treatment were associated with nicotinamide, branched-chain amino acid, methionine, cysteine, and taurine metabolism, indicative of a response to oxidative stress. MON 52276 had similar, but more pronounced, effects than glyphosate on the serum metabolome. Shotgun metagenomics of the cecum showed that treatment with glyphosate and MON 52276 resulted in higher levels of Eggerthella spp., Shinella zoogleoides, Acinetobacter johnsonii, and Akkermansia muciniphila. Shinella zoogleoides was higher only with MON 52276 exposure. In vitro culture assays with Lacticaseibacillus rhamnosus strains showed that Roundup GT plus inhibited growth at concentrations at which MON 52276 and glyphosate had no effect.Discussion:Our study highlights the power of multi-omics approaches to investigate the toxic effects of pesticides. Multi-omics revealed that glyphosate and MON 52276 inhibited the shikimate pathway in the rat gut microbiome. Our findings could be used to develop biomarkers for epidemiological studies aimed at evaluating the effects of glyphosate herbicides on humans. https://doi.org/10.1289/EHP6990

Mikania mikrantha leaf extract mediated biogenic synthesis of magnetic iron oxide nanoparticles: Characterization and its antimicrobial activity study

With an aim to introduce a new highly potent antimicrobial nanoparticles using an environment-friendly route, he present work reports the green synthesis of iron oxide nanoparticles (Fe3O4NPs) utilizing Mikania mikrantha leaf extract and its application as efficient antimicrobial agent. The green Fe3O4NPs have been described by X-beam diffraction (XRD), Ultraviolet–Visible (UV–Vis) spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Fourier Transform-Infra Red (FT-IR) investigation. The TEM image shows the rhomboidal Fe3O4NPs with average mean sizes 20.27 nm. The FT-IR investigation proved Fe3O4NPs have been balanced out through the associations of steroids, terpenoids, flavonoids, phenyl propanoids, phenolic acids and proteins present in the leaf extract. The synthesized Fe3O4NPs shows a very high antibacterial and antifungal property against 5 bacterial strains such as Bacillus cereus, Acinetobacter johnsonii, Pseudomonas aeruginosa, Achromobacter spanius and Chromobacterium pseudoviolaceum strain, and 4 fungal strains (Aspergillus niger, Penicillium citirinum, Fusarium oxysporium, and Candida albicans). The green synthesized iron oxide nanoparticles can interfere metabolic activities of microorganisms which determine its antimicrobial properties and could bring a promising application in the fields of medicine.

Bacteria contamination analysis on the hands and bowls of meatball cart vendors: an observational descriptive study

ObjectiveTo describe the presence of bacteria at the seller's hand of meatball vendors and cart meatball bowls. MethodThis is a descriptive study with an observational approach. Thirty mobile meatball vendors were recruited as participants. Therefore, the bacterias from bowls and hands were taken by swab sampling. The number of bacterias were obtained using total plate count method by means of nutrient agar. Bacteria types were identified using Gram staining method and bacteria assay. ResultsThe hands and bowls swab samples were positive for Gram-positive and Gram-negative bacteria in all cases. These microorganisms include Acinetobacter calcoaceticus, Klebsiella sp., Alcaligenes faecalis, Enterobacter aglomereus, Pseudomonas aeruginosa, Enterobacter aerogenes, Enterobacter cloacae, and Staphylococcus saprophyticus, Serratia rubidaea, Yersinia enterocolitica, E. aerogenes, and Staphylococcus epidermidis. ConclusionsSome types of bacterias were present in cart meatball bowls and the sellers’ hands. This phenomenon is affiliated with the emergence of food-borne diseases for the consumers.

Acinetobacter johnsonii Peritonitis in a Patient on Peritoneal Dialysis: A Case Report and Review of the Literature

Acinetobacter species have important role in modern medicine due to their increasing presence in health-care facilities and antibiotic resistance. They are non-fermentative, aerobic, Gram-negative coccobacilli and are important bacteria causing peritonitis in patients on peritoneal dialysis. Acinetobacter johnsonii is widely found in the aquatic environment and animals. Peritonitis caused by A. johnsonii is rarely encountered and reported. Here we report a case of A. johnsonii peritonitis in a patient on peritoneal dialysis. To the best of our knowledge, this is the first case of peritoneal dialysis-associated peritonitis by A. johnsonii reported from India.

Patogenesitas Bakteri Enterobacteriaceae pada Ikan Zebra (Danio rerio) Sebagai Hewan Model

Enterobacteriaceae are Gram negative bacteria contain endotoxin and exotoxins which are requirements for pathogenic bacteria and act as opportunistic pathogens. The purpose of this research was to determine the ability of Enterobacteriaceae bacteria to infect zebrafish (Danio rerio) by observing anatomical pathology, mortality, time death and cumulative time of death. The method used in this research is a completely randomized design method (CRD). This research was conducted in three stages, first preparation of zebrasfish as animal model by average size 3-5cm and reach three months old. Second, bacterial cultures from 10 species of Enterobacteriaceae were Escherichia coli 1, E. coli 2, Enterobacter cloacae 1, Acinetobacter calcoaceticus, Enterobacter amnigenus 1, Enterobacter amnigenus 1, Escherichia coli 3, Pantoea spp., E. cloacae 1, E. cloacae 2, E. cloacae 3, cultured in Brain Heart Infused Broth (BHIB) and later media washed with Phospate Buffer Saline (PBS) 0.45%. The third stage was bacterial infection to zebrafish using immersion method with each treatment repeated 3 times and observed for 120 hours. The results showed 10 species that used caused death (mortality), the highest mortality in fish that infected with E. coli 2 and E. cloacae 1 with a percentage of 66.67% infected by E. coli 2 and E. cloacae 1. Anatomical pathology in the external organs and internal organs showed post-infectious symptoms. Infection occurred with mean time to death of 12-86 hours, as long as the cumulative time of fish death caused by E. coli 2, A.cinetobacter calcoaceticus and E. cloacae 1 causing death from 24 hours after infection until the end of observation.

Biodegradation of organophosphorus pesticides in moving bed biofilm reactors: Analysis of microbial community and biodegradation pathways

We investigated the performance of a lab-scale moving bed biofilm reactor (MBBR) with respect to general bioconversion processes and biotransformation of two commonly used organophosphorus pesticides, Chlorpyrifos (CHL) and Malathion (MAL). The reactor was operated for 300 days under different organic loads by changing hydraulic retention time (HRT). The decrease in organic load resulted in the formation of a thinner biofilm and the growth of more biomass in the bulk, which greatly shifted bioconversion processes. The low organic loading supported more nitrification in the reactor, but an opposite trend was observed for denitrification, which was enhanced at higher organic loading where the formation of anoxic zones in the thick biofilm was favored. 70% and 55% removal corresponding to 210 and 165 µg/m2/d occurred for MAL and CHL, respectively, at an HRT of 3 h and progressively increased with higher HRTs. Phylogenetic analysis revealed a shift in composition and abundance of taxa throughout the reactor operation where lower loading rate supported the growth of a more diverse and evenly distributed community. The analysis also highlighted the dominance of heterotrophic communities such as Flavobacterium and Acinetobacter johnsonii, which could be involved in the biotransformation of CHL and MAL through co-metabolism.

Indigenous bacteria, an excellent reservoir of functional plant growth promoters for enhancing duckweed biomass yield on site

The advantages of aquatic biomass production using wastewater as a cost-free fertilizer have recently been highlighted. Here, we report a successful study in which duckweed, Lemna gibba, biomass production in a food factory effluent containing low nitrogen and high salts was enhanced by employing customized plant growth-promoting bacteria (PGPB). Two common PGPB strains previously obtained from natural pond water, Acinetobacter calcoaceticus P23 and Pseudomonas fulva Ps6, hardly promoted the growth of duckweed; on the contrary, they inhibited its growth in treated factory wastewater, far different water conditions. Then, we asked if some indigenous wastewater bacteria could promote the growth of duckweed. We found that Chryseobacterium strains, a group of bacteria with limited nitrogen metabolism, were dominantly selected as effective PGPB. Moreover, we demonstrated that nitrogen limitation is the crucial environmental factor that induces the plant growth-inhibiting behavior of A. calcoaceticus P23 through competition for mineral nutrients with the host duckweed. This study uncovered points to be considered in PGPB technology to achieve efficient production of duckweed biomass in a factory effluent with unbalanced content of mineral nutrients.

Characterization of the novel OXA-213-like β-lactamase OXA-822 from Acinetobacter calcoaceticus.

This study analysed the novel carbapenem-hydrolysing class D β-lactamase OXA-822 identified in the clinical Acinetobacter calcoaceticus isolate AC_2117. WGS was employed for identification of β-lactamases. Micro-broth dilution was used for evaluation of antibiotic susceptibility of AC_2117 and transformants containing blaOXA-822. After heterologous purification of OXA-822, OXA-359 and OXA-213, enzyme kinetics were determined using spectrometry. The effect of OXA-822 upon meropenem treatment was analysed in the Galleria mellonella in vivo infection model. OXA-822 is a member of the intrinsic OXA-213-like family found in A. calcoaceticus and Acinetobacter pittii. Amino acid sequence similarity to the nearest related OXA-359 was 97%. Production of OXA-822, OXA-359 and OXA-213 in Acinetobacter baumannii ATCC® 19606T resulted in elevated MICs for carbapenems (up to 16-fold). Penicillinase activity of the purified OXA-822 revealed high KM values, in the millimolar range, combined with high turnover numbers. OXA-822 showed the highest affinity to carbapenems, but affinity to imipenem was ∼10-fold lower compared with other carbapenems. Molecular modelling revealed that imipenem does not interact with a negatively charged side chain of OXA-822, as doripenem does, leading to the lower affinity. Presence of OXA-822 decreased survival of infected Galleria mellonella larvae after treatment with meropenem. Only 52.7% ± 7.7% of the larvae survived after 24 h compared with 90.9% ± 3.7% survival in the control group. The novel OXA-822 from a clinical A. calcoaceticus isolate displayed penicillinase and carbapenemase activity in vitro, elevated MICs in different species and decreased carbapenem susceptibility in A. baumannii in vivo.

The carbapenem resistance gene blaOXA-23 is disseminated by a conjugative plasmid containing the novel transposon Tn6681 in Acinetobacter johnsonii M19

BackgroundCarbapenem resistant Acinetobacter species have caused great difficulties in clinical therapy in the worldwide. Here we describe an Acinetobacter johnsonii M19 with a novel blaOXA-23 containing transposon Tn6681 on the conjugative plasmid pFM-M19 and the ability to transferand carbapenem resistance.MethodsA. johnsonii M19 was isolated under selection with 8 mg/L meropenem from hospital sewage, and the minimum inhibitory concentrations (MICs) for the representative carbapenems imipenem, meropenem and ertapenem were determined. The genome of A. johnsonii M19 was sequenced by PacBio RS II and Illumina HiSeq 4000 platforms. A homologous model of OXA-23 was generated, and molecular docking models with imipenem, meropenem and ertapenem were constructed by Discovery Studio 2.0. Type IV secretion system and conjugation elements were identified by the Pathosystems Resource Integration Center (PATRIC) server and the oriTfinder. Mating experiments were performed to evaluate transfer of OXA-23 to Escherichia coli 25DN.ResultsMICs of A. johnsonii M19 for imipenem, meropenem and ertapenem were 128 mg/L, 48 mg/L and 24 mg/L, respectively. Genome sequencing identified plasmid pFM-M19, which harbours the carbapenem resistance gene blaOXA-23 within the novel transposon Tn6681. Molecular docking analysis indicated that the elongated hydrophobic tunnel of OXA-23 provides a hydrophobic environment and that Lys-216, Thr-217, Met-221 and Arg-259 were the conserved amino acids bound to imipenem, meropenem and ertapenem. Furthermore, pFM-M19 could transfer blaOXA-23 to E. coli 25DN by conjugation, resulting in carbapenem-resistant transconjugants.ConclusionsOur investigation showed that A. johnsonii M19 is a source and disseminator of blaOXA-23 and carbapenem resistance. The ability to transfer blaOXA-23 to other species by the conjugative plasmid pFM-M19 raises the risk of spread of carbapenem resistance.Graphic abstractThe carbapenem resistance gene blaOXA-23 is disseminated by a conjugative plasmid containing the novel transposon Tn6681 in Acinetobacter johnsonii M19.

Identification two key residues at the intersection of domains of a thioether monooxygenase for improving its sulfoxidation performance

AcCHMO, a cyclohexanone monooxygenase from Acinetobacter calcoaceticus, is a typical Type I Baeyer-Villiger monooxygenase (BVMO). We previously obtained the AcCHMOM6 mutant, which oxidizes omeprazole sulfide (OPS) to the chiral sulfoxide drug esomeprazole. To further improve the catalytic efficiency of the AcCHMOM6 mutant, a focused mutagenesis strategy was adopted at the intersections of the FAD-binding domain, NADPH-binding domain, and α-helical domain based on structural characteristics of AcCHMO. By using focused mutagenesis and subsequent global evolution two key residues (L55 and P497) at the intersections of the domains were identified. Mutant of L55Y improved catalytic efficiency significantly, whereas the P497S mutant alleviated substrate inhibition remarkably. AcCHMOM7 (L55Y/P497S) was obtained by combining the two mutations, which increased the specific activity from 18.5 (M6) to 108 U/g, and an increase in the Ki of the substrate OPS from 34 to 265 μM. The results indicate that catalytic performance can be elevated by modification of the sensitive sites at the intersection of the domains of AcCHMO. The results also provided some insights for the engineering of other Type I BVMOs or other multidomain proteins.

Antibacterial potential of green magnesium oxide nanoparticles against rice pathogen Acidovorax oryzae

Magnesium oxide nanoparticles (MgONPs) have emerged as effective antibacterial agents with unique physiochemical properties. Here, we report antibacterial activity of MgONPs produced by using Acinetobacter johnsonii strain RTN1 against rice pathogen Acidovorax oryzae for the first time. The physico-chemical and optical properties of biogenic MgONPs were elucidated by using UV–vis spectroscopy, FTIR, XRD, EDS, SEM, and TEM. Biogenic MgONPs showed substantial antibacterial activity (35.2 ± 0.61 mm zone of inhibition) against A. oryzae at 20 µg mL−1 and significantly reduced cell density (80.83% MIC at OD600) of pathogen in broth culture. The ultrastructure studies revealed the morphological disruptions in MgONPs-treated A. oryzae cells as compared to control. Hence, the MgONPs could be used to formulate a potent nanopesticide for A. oryzae.

Immobilization of Purified Pectin Lyase from Acinetobacter calcoaceticus onto Magnetic Carboxymethyl Cellulose Nanoparticles and Its Usability in Food Industry

An important component of the pectinase enzyme complex is pectin lyase (polymethylgalacturonate lyase; EC 4.2.2.10). In this study, extracellular pectin lyase enzyme was produced from Acinetobacter calcoaceticus bacteria. Pectin lyase was then purified using three-phase precipitation (TPP) technique with 25.5% yield. The pectin lyase was immobilized covalently via the L-glutaraldehyde spacer to the carboxymethyl cellulose. The immobilized pectin lyase was magnetized using Fe3O4 nanoparticles. Purified pectin lyase was connected to magnetized support material after 90 min at the rate of 80%. The most appropriate immobilization conditions were determined as pH 8 and 30°C. By characterizing the free and immobilized enzyme, KM, Vmax, and optimum pH and optimum temperature values were determined. It was optimum pH 8 and temperature 50°C for both free and immobilized pectin lyase. The structural characterization of the immobilized pectin lyase modified with Fe3O4 nanoparticles was carried out by SEM, FT-IR, and XRD chromatographic analyses. At the end of the study, free and immobilized enzymes were used for purification of some fruit juices and results were compared.

Effect of quorum sensing and quenching molecules on inter-kingdom biofilm formation by Penicillium expansum and bacteria

The ecology of a biofilm is a complex function of different factors, including the presence of microbial metabolites excreted by the inhabitants of the biofilm. This study aimed to assess the effect of patulin, and N-(3-oxododecanoyl)-L-homoserine lactone (3-oxo-C12-HSL) on inter-kingdom biofilm formation between a filamentous fungus and bacteria isolated from drinking water. The filamentous fungus Penicillium expansum and the bacteria Acinetobacter calcoaceticus and Methylobacterium oryzae were used as model species. M. oryzae biofilm formation and development was more susceptible to the presence of the quenching molecules than A. calcoaceticus biofilms. Patulin reduced M. oryzae biofilm growth while 3-oxo-C12-HSL caused an increase after 48 h. The presence of P. expansum had a detrimental effect on M. oryzae cell numbers, while an advantageous effect was observed with A. calcoaceticus. The overall results reveal that quorum sensing and quenching molecules have a significant effect on inter-kingdom biofilm formation, especially on bacterial numbers.

Identification of Bithionol, Dichlorophen, and Miconazole as Antibacterial Agents against Acinetobacter calcoaceticus.

The rising prevalence of multidrug-resistant hospital-acquired infections has increased the need for new antibacterial agents. In this study, a library of 1586 FDA-approved drugs was screened against A. calcoaceticus, a representative of the Acinetobacter calcoaceticus–baumannii complex. Three compounds were found to have previously undiscovered antibacterial properties against A. calcoaceticus: antifungal Miconazole, anthelminthic Dichlorophen, and Bithionol. These three drugs were tested against a wide range of Gram-positive and Gram-negative bacteria and confirmed to have broad-spectrum antibacterial properties. Combinations of these three drugs were also tested against the same bacteria, and two novel combination therapies with synergistic effects were discovered. In the future, antibacterial properties of these three drugs and two combination therapies will be evaluated against pathogenic bacteria using an animal model.

Antibiotic resistance mechanisms in Acinetobacter spp. strains isolated from patients in a paediatric hospital in Mexico

ObjectivesThe aim of this study was to identify Acinetobacter spp. strains from paediatric patients, to determine their genetic relationship, to detect antibiotic resistance genes and to evaluate the role of efflux pumps in antibiotic resistance. MethodsA total of 54 non-duplicate, non-consecutive Acinetobacter spp. isolates were collected from paediatric patients. Their genetic relationship, antibiotic resistance profile, efflux pump activity, antibiotic resistance genes and plasmid profile were determined. ResultsThe isolates were identified as 24 Acinetobacter haemolyticus, 24 Acinetobacter calcoaceticus–baumannii (Acb) complex and 1 strain each of Acinetobacter junii, Acinetobacter radioresistens, Acinetobacter indicus, Acinetobacter lwoffii, Acinetobacter ursingii and Acinetobacter venetianus. The 24 A. haemolyticus were considered genetically unrelated. One strain was resistant to carbapenems, two to cephalosporins, two to ciprofloxacin and sixteen to aminoglycosides. The antibiotic resistance genes blaOXA-214 (29%), blaOXA-215 (4%), blaOXA-264 (8%), blaOXA-265 (29%), blaNDM-1 (4%), aac(6ʹ)-Ig (38%) and the novel variants blaOXA-575 (13%), blaTEM-229 (75%), aac(6ʹ)-Iga (4%), aac(6ʹ)-Igb (13%) and aac(6ʹ)-Igc (42%) were detected. Among 24 Acb complex, 5 were multidrug-resistant, carbapenem-resistant strains carrying blaOXA-51 and blaOXA-23; they were genetically related and had the same plasmid profile. Other species were susceptible. In some strains of A. haemolyticus and Acb complex, the role of RND efflux pumps was evidenced by a decrease in the MICs for cefotaxime, amikacin and ciprofloxacin in the presence of an efflux pump inhibitor. ConclusionsThis study identified isolates of A. haemolyticus carrying new β-lactamase variants and shows for the first time the contribution of efflux pumps to antibiotic resistance in this species.

Factors Affecting Bacterial Adhesion on Selected Textile Fibres.

In sectors like healthcare and hospitality, it has been realized that fabrics play a pivotal role in transfer of nosocomial infections. However, there is a major gap in drawing correlation between different fibre types and their interaction with microorganisms. Such information is important to formulate guidelines for textile materials for use in these sectors. In the current study, the adherence of four important bacteria, Staphylococcus aureus, Acinetobacter calcoaceticus, Escherichia coli, and Pseudomonas aeruginosa was studied on six different fibre types namely polyester, wool, polypropylene, viscose, silk and cotton. Among these fibres, viscose showed maximumadherence while silk fibres showed the least attachmentof bacterial strains. Bacterial adhesion was correlated with the surface characteristics (surface charge, hydrophobicity etc.) of bacteria, and nanoroughness of fibres. Adhesion of these bacteria was tested on five hydrocarbons of different hydrophobicities. E. coli, the weakest biofilm producer, and with the highest surface energy and lowest hydrophobicity amongst the bacteria compared in the study, had the lowest load on all fibres. Scanning electron microscopy revealed non-uniform binding of gram-negative and gram-positive bacteria. Nanoroughness of fibres favored bacterial adhesion. The study showed correlation between surface properties and adherence of bacteria on fibres, with the results being of direct significance to medical and hospitality sectors.

Characterization of Ligninolytic Bacteria and Analysis of Alkali-Lignin Biodegradation Products.

Ligninolytic bacteria degrading lignin were isolates and identified, and their biodegradation mechanism of alkaline-lignin was investigated. Four strains with lignin degradation capability were screened and identified from the soil, straw, and silage based on their decolorizing capacity of aniline blue and colony size on alkaline-lignin medium. The degradation ratio of Bacillus aryabhattai BY5, Acinetobacter johnsonii LN2, Acinetobacter lwoffii LN4, and Micrococcus yunnanensis CL32 have been assayed using alkaline-lignin as the unique carbon source. Further, the Lip (lignin peroxidase) and Mnp (manganese peroxidase) activities of strains were investigated. Lip activity of A. lwoffii LN4 was highest after 72 h of incubation and reached 7151.7 U · l–1. Mnp activity of M. yunnanensis CL32 was highest after 48 h and reached 12533 U · l–1. The analysis of alkaline-lignin degradation products by GC-MS revealed that the strains screened could utilize aromatic esters compounds such as dibutyl phthalate (DBP), and decomposite monocyclic aromatic compounds through the DBP aerobic metabolic pathway. The results indicate that B. aryabhattai BY5, A. johnsonii LN2, A. lwoffii LN4, and M. yunnanensis CL32 have high potential to degrade alkaline-lignin, and might utilize aromatic compounds by DBP aerobic metabolic pathway in the process of lignin degradation.

Multidrug Resistant Acinetobacter Isolates Release Resistance Determinants Through Contact-Dependent Killing and Bacteriophage Lysis.

Antimicrobial resistance is an ancient bacterial defense mechanism that has rapidly spread due to the frequent use of antibiotics for disease treatment and livestock growth promotion. We are becoming increasingly aware that pathogens, such as members of the genus Acinetobacter, are precipitously evolving drug resistances through multiple mechanisms, including the acquisition of antibiotic resistance genes. In this study, we isolated three multidrug resistant Acinetobacter species from birds on a free-range farm. Acinetobacter radioresistens, Acinetobacter lwoffii, and Acinetobacter johnsonii were isolated from hens, turkeys and ducks and were resistant to 14 clinically relevant antibiotics, including several listed by the World Health Organization as essential medicines. Co-culturing any of the three Acinetobacter species with Acinetobacter baumannii resulted in contact-dependent release of intact resistance determinants. We also isolated several lytic bacteriophages and selected two of these phages to be included in this study based on differences in plaquing characteristics, nucleic acid content and viral morphology. Both phages released host DNA, including antibiotic resistance genes during cell lysis and we demonstrated that these resistance determinants were transferable to a naïve strain of Escherichia coli. This study demonstrates that contact-dependent competition between bacterial species can readily contribute to DNA release into the environment, including antibiotic resistance determinants. We also highlight that the constant lysis and turnover of bacterial populations during the natural lifecycle of a lytic bacteriophage is an underappreciated mechanism for the liberation of DNA and subsequent genetic exchange.

Selective synthetic growth medium “Acinetobacter phenylalanine agar” for isolation and identification of Acinetobacter calcoaceticus — Acinetobacter baumannii complex species

The aim of the study was to carry out clinical and microbiological testing of selective growth medium Acinetobacter phenylalanine agar to isolate and identify bacterial species belonging to the Acinetobacter calcoaceticus — Acinetobacter baumannii complex (ACB complex). For this, 400 samples of clinical material (wound discharge, blood, urine, bronchoalveolar lavage) were examined in 2018 in the Clinical and Bacteriological Laboratory of the Military Medical Academy by using routine assays (seeding on blood agar growth medium, pure culture isolation and identification by using biochemical assays as well as VITEK 2 microbial identification system, bioMerieux) and plating together with growth medium Acinetobacter phenylalanine agar selective to Acinetobacter spp. owing to L-phenylalanine as a sole nitrogen and carbon source additional selected with trimethoprim. ACB complex Acinetobacters were identified 18–24 hours later after incubation at 37°C by emergence of typical colonies on selective medium. Control tests for cytochrome oxidase as well as oxidative/fermentation (OF)-glucose test by using peroxide-hydrogen microvolume method (for 1 h) allowed to rapidly distinguish ACB complex Acinetobacters from other bacteria as well as from Acinetobacter spp. unable to glucose oxidation. Next, species identity for all isolated Acinetobacter strains was established by using matrix-activated laser desorption/ionization with time-of-flight mass spectrometry (MALDI-TOF MS). It was found that by using novel vs. routine assay Acinetobacter spps. were isolated in 26 (18 samples — in monoculture, 8 — in association with Pseudomonas aeruginosa or Klebsiella pneumoniae subsp. pneumoniae with tiny associate colonies) vs. 20 (7 — in monoculture, 13 — in association with Pseudomonas aeruginosa, Klebsiella, Escherichia, Citrobacter, Providencia, Staphylococcus, Enterococcus, C. albicans). Using MALDI-TOF MS method revealed that 25 out of 26 Acinetobacter strains isolated on selective growth medium belonged to the ACB complex (A. baumannii — 23, A. pittii — 2), whereas one strain (A. baylyi) did not belong to ACB complex. Hence, the diagnostic specificity of the Acinetobacter phenylalanine agar synthetic growth medium for isolation and identification of the A. calcoaceticus — A. baumannii complex species comprised 96.2%, with diagnostic sensitivity exceeding that one for routine assay by 25%. Use of selective growth medium accelerates research by allowing to isolate and identify ACB complex Acinetobacter spp. 18–24 h later after plating clinical material. Selectivity of growth medium was potentially stable, as its major trophic selection factor did not depend on acquired bacterial antibiotic resistance, which is also suitable as a synthetic growth medium for standardized studies.