Achromobacter Denitrificans Research Articles

Phenotypic and Genetic Characterization of Carbapenemase and ESBLs Producing Gram-negative Bacteria (GNB) Isolated from Patients with Cystic Fibrosis (CF) in Tehran Hospitals.

Cystic Fibrosis (CF) is an autosomal recessive genetic disorder in white populations caused by mutation in a gene that encodes Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) protein. Since frequent respiratory tract infections are the major problem in patients with CF, obligation to identify the causative bacteria and determining their antibiotic resistance pattern is crucial. The purpose of this project was to detect Gram-negative bacteria (GNB) isolated from sputa of CF patients and to determine their antibiotic resistance pattern. The sputum of 52 CF patients, treated as inpatients at hospitals in Tehran, was obtained between November 2011 and June 2012. Samples cultured in selective and non-selective media and GNB recognized by biochemical tests. Antimicrobial susceptibility testing to cephalosporins, aminoglycosides and carbapenems was performed by disk diffusion method and MICs of them were measured. For phenotypic detection of carbapenemase and ESBLs production, the Modified Hodge test, double disk synergy test and the combined disk methods were performed. Subsequently, the genes encoding the extended spectrum beta-lactamases (blaPER, blaCTX-M) and carbapenemases (blaIMP-1, blaGES, blaKPC, blaNDM, blaVIM-1, blaVIM-2, blaSPM, blaSIM) in Gram negative bacteria were targeted among the resistant isolates by using PCR. PFGE was used to determine any genetic relationship among the Pseudomonas aeruginosa isolated from these patients. Fifty five GNB were isolated from 52 sputum samples including Pseudomonas aeruginosa, Klebsiella ozaenae, Alcaligenes xylosoxidans, Achromobacter denitrificans, Klebsiella pneumonia and Stenotrophomonas maltophilia. The rates of resistance to different antibiotic were as follows: cefixime (%80), ceftriaxone (%43), ceftazidime (%45) and meropenem (%7). The prevalence of genes encoding the ESBLs and Carbapenemases among the the phenotypically positive strains were as follows: blaCTX-M (19), blaIMP-1 (2), blaVIM-1 (2) and blaVIM-2 (3) genes respectively. No other genes were detected. PFGE analysis revealed 8 genotypes. Six isolates had mutually 3 similar patterns. This study showed the existence of important ESBLs and carbapenemases genes among the GNB isolated from patients with CF. Continuous surveillance of ESBLs and Carbapenemases, also identification of their types, in bacteria isolated from these patients have an important clinical impact, since, it can often provide valuable information for effective infection control measures and for the choice of appropriate antimicrobial therapy.

A Teenager Patient With Recurrent Pulmonary Abscesses.

A 15-year-old Hispanic male presented with a history of fever, productive cough, and chest pain for 3 days. He had yellow-orange sputum and complained of chest pain on his left side exacerbated by cough and deep inspiration. Twelve months before the current admission, he was diagnosed with left lower lobe pneumonia with lung abscess. The sputum culture grew methicillin-sensitive Staphylococcus aureus. Hewas treated with intravenous ampicillin-sulbactam for 3 weeks, followed by oral amoxicillin-clavulanate therapy for another 3 weeks. Eight months before the current admission, he was again hospitalized with left lower lobe pneumonia and received treatment with intravenous ceftriaxone for 4 days and oral azithromycin for another 5 days. The patient rapidly clinically improved on these therapies, and no further work up was obtained and no organism was recovered from blood culture. The patient had no history of recent travel, no tuberculosis (TB) exposure, or TB risk factors. He denied smoking or illicit drugs use. He was diagnosed with asthma at 12 years of age and used albuterol inhaler infrequently, namely with exertion. On physical examination, the patient was alert, well nourished, and not in respiratory distress. Vitals signs included a temperature of 36.8°C, pulse 85 beats per minute, respirations 20 breaths per minute, blood pressure 96/60, and oxygen saturation 94% in room air. The patient had a prominent forehead and a broad nasal bridge (Figure 1). Poor dentition and high-arched palate were also visualized (Figure 2). Auscultation of the lungs revealed decreased breath sounds over the left lower lobe. The remainder of the physical examination was unremarkble. White cell count was 9900/mm (range, 4900–13 300/ mm) with a differential of 49%neutrophils, 25% lymphocytes, 6% monocytes, and 20% eosinophils. The C-reactive protein was 61 mg/L (normal, <9.1 mg/L) and sedimentation rate was 19 mm/h (range, 0–14 mm/h). The chest radiograph was remarkable for a cavitary lesion with air fluid level in the left lower lobe. Chest computed tomography confirmed a bi-lobed, thin-walled, fluid-containing cavity 11.9 × 7.2 × 10 cm, located in the left lower lobe with surrounding consolidation. Sputum culture grew Aspergillus fumigatus and Achromobacter denitrificans. The patient was started on intravenous ampicillin-sulbactam treatment. Fluid from a bronchial alveolar lavage revealed nucleated cells of 15,197/mm (85% eosinophils). Bronchial alveolar lavage specimen culture grew Streptococcus mitis and A fumigatus. Bronchial alveolar lavage fluid galactomannan index was 0.8 (normal, <0.5). Based on culture results, therapy was changed to intravenous vancomycin, meropenem, and voriconazole. The patient developed a left hydropneumothorax that required video-assisted thoracic surgery with chest tube insertion. Seven hundred and fifty milliliters of purulent fluid was drained. Due to persistence of hydropneumothorax, a left lower lobectomy was performed. A computed tomography of the paranasal sinuses demonstrated mild mucosal thickening in the sphenoid and maxillary sinuses was noted (Figure 3, right). In addition, multiple un-erupted and partially erupted teeth were noted (Figure 3, left).

Role of associative bacterial interaction in the induction of tuber rot incidence in cassava (Manihot esculenta Crantz)

Cassava (Manihot esculenta Crantz), one of the leading staples in the world, has considerable scope for integration into emerging markets through efficient and environmentally sound production of a diversified range of high quality, competitive products for food, feed and industry. One of the major reasons attributed to the low productivity of cassava in India is the incidence of tuber rot in cassava incited by Phytophthora palmivora. Usually, an array of microorganisms is involved in rotting of cassava tubers in the field and in postharvest conditions. Unfortunately, the disease management practices focus mainly on fungal pathogens. In this article, we tried to investigate the role of associative bacterial pathogens in induction of tuber rot of cassava, the potential of the bacteria with P. palmivora in causing disease incidence, spread and rotting. The bacteria and P. palmivora were originally isolated from tuber rot infected cassava from the field having a disease incidence percentage of above 40%, checked for pathogenicity and were proven for Koch postulate. The detached tubers of disease resistant (cv. Sree Pathmanabha) and susceptible cultivars (cv. M4) of cassava were used for the study. The effect of bacterial association was studied in Cassava agar plate assay, in detached tubers and in in planta experiments in in vitro glass house conditions. The bacterial isolates were identified as Gram-negative coco bacilli of class Pseudomonas, Erwinia amylovora and Achromobacter denitrificans.

Modification of surface and enzymatic properties of Achromobacter denitrificans and Stenotrophomonas maltophilia in association with diesel oil biodegradation enhanced with alkyl polyglucosides

The article concerns the influence of selected alkyl polyglucosides on biodegradation, cell surface and enzymatic properties of Stenotrophomonas maltophilia and Achromobacter denitrificans.The biodegradation of diesel oil depends on several factors including type and the amount of surfactant as well as bacterial genera used in the process. Nevertheless, a careful selection of these variables must be made as some bacterial strains prefer to use surfactants as their carbon source. This leads to the lowered biodegradation of diesel oil as can be observed for the tested S. maltophilia strain. Alkyl polyglucosides influenced the cell surface properties of both of the tested strains in slightly different ways. Especially for A. denitrificans, for which the hydrophobicity increased with concentration of both – Lutensol GD 70 and Glucopon 215 in diesel oil–surfactant systems. Moreover, judging by the efficiency of biodegradation, the most effective process was observed in the presence of Lutensol GD 70 (240 and 360mgL−1) with biodegradation rising from 32% (without surfactant) to 68%. No such relation was observed for S. maltophilia.

Chemical Characterization and Antibacterial Activity of Two Aromatic Herbs (Santolina chamaecyparissus and Sideritis angustifolia) Widely Used in the Folk Medicine

AbstractThe aim of this work was characterize the essentials oils (EOs) obtained from Santolina chamaecyparissus and Sideritis angustifolia determining (1) its chemical composition and (2) its effectiveness on the growth of some bacteria related to food spoilage, such as Listeria innocua, Serratia marcescens, Pseudomonas fragi, Pseudomonas fluorescens, Aeromonas hydrophila, Shewanella putrefaciens, Alcaligenes faecalis, Achromobacter denitrificans, Enterobacter amnigenus, Enterobacter gergoviae and Leuconostoc carnosum. The EOs were chemically analyzed and identified by gas chromatography and gas chromatography/mass spectrometry, while the agar disc diffusion method was used to determine their antibacterial activities. The concentration effect was also determined. In S. chamaecyparissus, the major constituents were artemisia ketone (27.19%), dihydroaromadendrene (18.21%) and β‐phellandrene (7.49%), while in S. angustifolia EO, the major constituent is α‐pinene (12.71%). Another important compound was β‐phellandrene (11.97%). The agar disc diffusion method indicated that S. chamaecyparissus EO showed the highest antibacterial activity against the L. innocua and A. hydrophila, with inhibition zones of 12.70 and 16.50 mm, respectively. S. angustifolia EO showed the highest antibacterial activity against A. faecalis, S. marcescens and A. denitrificans. S. chamaecyparissus and S. angustifolia EOs can be used as antibacterial agents.Practical ApplicationsThe research on plant‐based natural bioactive compounds to control the foodborne and spoilage pathogens has attained special interest in the recent years. The use of essential oils of Santolina chamaecyparissus and Sideritis angustifolia as antibacterial agents will be suitable for applications on the food industry as natural preservatives or flavoring to control foodborne pathogens. Another important reason for their suitability is their natural origin, which consumers find comforting.

In vitro antibacterial and antioxidant properties of chitosan edible films incorporated with Thymus moroderi or Thymus piperella essential oils

The aim of this work was to evaluate chitosan edible films incorporated with the EOs of two aromatic herbs, Thymus moroderi and Thymus piperella for (i) the growth inhibition of some bacterial strains (ii) their total phenolic content (TPC), and (iii) their antioxidant activity by means of three different antioxidant tests to define if the chitosan edible films incorporated with these EOs could be used as natural active films for food use. The agar disc diffusion method was used to determine the antibacterial activities of chitosan edible films. For the antioxidant activity, three different analytical assays were used (DPPH, FRAP and FIC). The chitosan films containing T. piperella EO (CH + TPEO) were more effective (p < 0.05) against Serratia marcenscens and Listeria innocua than chitosan films containing T. moroderi EO (CH + TMEO), while no statistically differences were found (p > 0.05) between CH + TPEO and CH + TMEO against Aeromonas hydrophila and Achromobacter denitrificans. The CH + TMEO films showed lower (p < 0.05) antioxidant activity, at all concentrations and with all methods assayed, than CH + TPEO. The antioxidant activity occurred in a concentration dependent manner.The results showed that chitosan edible films incorporated with T. piperella and T. moroderi EOs could be used as active films due to its excellent antibacterial and antioxidant activities.

Food preservative potential of gassericin A‐containing concentrate prepared from cheese whey culture supernatant of Lactobacillus gasseri LA39

Gassericin A (GA) is a circular bacteriocin produced by Lactobacillus gasseri LA39. In this study, GA-containing concentrate was prepared using a cross-flow membrane filtration device (30 kDa cut-off) from the culture supernatant of Lb. gasseri LA39 cultivated in a cheese whey-based food-grade medium. The bacteriocin activity titer in the concentrate was 16 times as high as that of the culture supernatant and was completely maintained through each incubation at 4°C for 3 months, 37°C for 2 months, 60°C for 5 h, and 100°C for 30 min. The GA-containing concentrate was used with glycine powder to make custard creams, and then four representative strains of custard cream spoilage bacteria (Bacillus cereus, Lactococcus lactis subsp. lactis, Achromobacter denitrificans and Pseudomonas fluorescens) were individually inoculated at c. 10(3) colony forming units/g in the custard creams. Throughout 30 days of incubation at 30°C, all of the inoculated bacteria were completely inhibited by the combination of 5% (w/w) of the GA-containing concentrate and 0.5% (w/w) glycine. This is the first highly practical application of GA to foods as a biopreservative, and the concentration method and the bacteriocin concentrate would contribute to biopreservation of several foods.

Brote hospitalario de Achromobacter denitrificans relacionado con el uso de clorhexidina contaminada

The aim of this paper is to describe a case series of pseudobacteremia caused by Achromobacter denitrificans, isolated from blood cultures from 14 hospitalized patients in a tertiary care institution in Medellin. The cases were associated with the use of contaminated 4% chlorhexidine soap. All patients received antibiotic treatment and had favorable results, possibly because of the low virulence of this organism and the timely measures taken by the hospital infections control group.

Continuous Ambulatory Peritoneal Dialysis–Related Exit-Site Infections Caused by Achromobacter denitrificans and A. Xylosoxidans

From 2006 to 2010, 20 of 244 patients who underwent placement of a straight two-cuffed Tenckhoff PD catheter experienced acute pericannular bleeding. The first management strategy failed in 6 patients (30%). The second management strategy was applied in those 6 patients, and the bleeding stopped within 24 hours. Blood transfusion was not required, and no exit-site infection was detected during follow-up. Postoperative pericannular bleeding is considered to have both medical and surgical causes. From the medical point of view, patients who undergo PD catheter insertion usually have coagulation dysfunction even if the results of regular blood tests are normal. From the surgical point of view, the bleeders are usually located near the external cuff, because the Dacron cuff easily sticks over the subcutaneous layer, with the bleed developing after tissue rub. Such bleeds are usually too deep to check, and conservative management appears cost effective. Postoperative acute pericannular bleeding is usually regarded as a self-limiting condition, and it is seldom recorded. Pericannular bleeding leading to hematoma formation increases the risk of catheter-related infection and may compromise catheter survival. Although our strategies are effective in stopping bleeding, they still have potential risks for catheter injury and pericatheter infection. Standard skin sterilization and meticulous injection techniques are important.

Chemical characterization and antibacterial activity of Thymus moroderi and Thymus piperella essential oils, two Thymus endemic species from southeast of Spain

The aim of this work was to determine the following characteristics of the essentials oils (EOs) obtained from two Thymus endemic species such as Thymus moroderi and Thymus piperella: (i) their chemical composition and (ii) their effect on the growth of several bacteria related to food spoilage, such as Listeria innocua, Serratia marcenscens, Pseudomonas fragi, Pseudomonas fluorescens, Aeromonas hydrophila, Shewanella putrefaciens, Achromobacter denitrificans, Enterobacter amnigenus, Enterobacter gergoviae, Alcaligenes faecalis and Leuconostoc carnosum. The EOs were chemically analysed and identified by GC and GC–MS, while the agar disc diffusion method was used to determine their antibacterial activities. The concentration effect was also determined.The major constituents of T. moroderi EO were camphor (26.74%), 1,8-cineol (24.99%) and myrcene (5.63%). In the T. piperella EO the main constituents were carvacrol (31.92%), para-cymene (16.18%) and γ-terpinene (10.11%). T. piperella EO was much more effective than T. moroderi EO, and had a much greater effect on the Gram-positive bacteria than on the Gram-negative bacteria.

Nonspecific Bacterial Flora Isolated from the Body Surface and Inside Ixodes ricinus Ticks

Ixodes ricinus and other representatives of the order Ixodida are vectors of typical pathogens: Borrelia burgdorferi sensu lato, Anaplasma phagocytophilium, Babesia spp., a tick-borne encephalitis virus, and other microorganisms which are important from a medical and veterinary point of view. The presented study focuses on the verification of nonspecific bacterial flora of I. ricinus. We analyzed ticks collected in a forest region in Silesia, an industrial district in Poland. Methods of classical microbiology and biochemical assays (API 20 NE test, API Staph test and MICRONAUT System) were used for isolation and identification of microorganisms living on the body surface of I. ricinus and inside ticks. The results show the presence of various bacteria on the surface and inside ticks' bodies. During the study, we isolated Acinetobacter lwoffi, Pseudomonas fluorescens, Aeromonas hydrophila, Achromobacter denitrificans, Alcaligenes faecalis, Stenotrophomonas maltophilia, Pseudomonas oryzihabitans, Micrococcus spp., Kocuria varians, Staphylococcus lentus, Kocuria kristinae, Streptococcus pneumoniae, Rhizobium radiobacter, Staphylococcus xylosus. Majority of the isolated species are non-pathogenic environmental microorganisms, but some of the isolated bacterial strains could cause severe infections.

Visualization and Direct Counting of Individual Denitrifying Bacterial Cells in Soil by nirK-Targeted Direct in situ PCR

The abundance of denitrifying bacteria in soil has been determined primarily by the conventional most probable number (MPN) method. We have developed a single-cell identification technique that is culture-independent, direct in situ PCR, to enumerate denitrifying bacteria in soils. The specificity of this method was evaluated with six species of denitrifying bacteria using nirK as the target gene; Escherichia coli was used as a negative control. Almost all (97.3%-100%) of the nirK-type denitrifying bacteria (Agromonas oligotrophica, Alcaligenes faecalis, Achromobacter denitrificans, Bradyrhizobium japonicum, and Pseudomonas chlororaphis) were detected by direct in situ PCR, whereas no E. coli cells and only a few cells (2.4%) of nirS-type denitrifying bacteria (Pseudomonas aeruginosa) were detected. Numbers of denitrifying bacteria in upland and paddy soil samples quantified by this method were 3.3 × 10(8) to 2.6 × 10(9) cells g(-1) dry soil. These values are approximately 1,000 to 300,000 times higher than those estimated by the MPN method. These results suggest that direct in situ PCR is a better tool for quantifying denitrifying bacteria in soil than the conventional MPN method.

Pusillimonas ginsengisoli sp. nov., isolated from soil of a ginseng field

Two novel strains of Gram-negative, non-sporulating, short rod-shaped, motile bacteria, designated DCY25T and DCY28, were isolated from soil of a ginseng field in South Korea and characterized in order to determine their taxonomic position. 16S rRNA gene sequence analysis showed that strains DCY25T and DCY28 belonged to the Betaproteobacteria, the highest sequence similarities being found with Pusillimonas noertemannii BN9T (96.9%), Bordetella trematum DSM 11334(T) (95.9%), Achromobacter denitrificans DSM 30026T (95.9%), Achromobacter insolitus LMG 6003T (95.8%) and Pigmentiphaga kullae K24T (95.5%). Chemotaxonomic data revealed that both strains DCY25T and DCY28 possessed ubiquinone Q-8. Fatty acid analysis of strain DCY25T demonstrated the presence of 19:0 cyclo omega8c (22.8%) and 16:0 (16.6%). The polar lipid profiles of strains DCY25T and DCY28 included phosphatidylethanolamine, phosphatidylglycerol, two unknown aminolipids and diphosphatidylglycerol. The G+C contents of strains DCY25T and DCY28 were 57.3 and 57.2 mol%, respectively. DNA-DNA relatedness values, biochemical and physiological characteristics strongly supported the genotypic and phenotypic differentiation of strains DCY25T and DCY28 from Pusillimonas noertemannii. Therefore, strains DCY25T and DCY28 should be classified in a novel species, for which the name Pusillimonas ginsengisoli sp. nov. is proposed. The type strain is DCY25T (=KCTC 22046T =JCM 14767T); strain DCY28 (=KCTC 22047=JCM 14768) is a reference strain.

Effects of gassericins A and T, bacteriocins produced by Lactobacillus gasseri, with glycine on custard cream preservation

Lactobacillus gasseri LA39 and LA158 isolated from human-infant feces produce bacteriocins named gassericins A and T, respectively. Both gassericins have high heat stability (121°C, 10min), good pH tolerance (pH 2–11), and strong bactericidality against many gram-positive bacteria, especially lactic acid bacteria, and thus are expected to be effective food preservatives. A microwell plate assay against 12 strains of custard cream spoilage bacteria showed that the gassericins had broader antibacterial spectra than nisin A. Although the gassericins allowed gram-negative isolates to grow, they successfully inhibited the growth of all tested bacterial strains in microwells with the addition of glycine. Glycine was bacteriostatic against many strains except lactic acid bacteria. For practical use, gassericin A was efficiently produced by cultivation in a food-grade medium improved using cheese whey, nourishing proteose peptone, and surfactant yolk lecithin. The practical preservative effect of gassericin A and glycine was verified from the viability of 4 isolated strains, Bacillus cereus, Lactococcus lactis ssp. lactis, Achromobacter denitrificans, and Pseudomonas fluorescens, in custard creams. Custard cream containing 123 arbitrary units of gassericin A per milliliter entirely growth-inhibited the 2 gram-positive strains. In custard cream containing an insufficient amount of gassericin A (49 arbitrary units/mL), the gram-positive strains gradually grew but were completely inhibited by the addition of 0.5% (wt/wt) glycine. The 2 gram-negative strains did not multiply even in the additive-free custard cream, probably because of the unsuitable growth environment. This is the first report showing the combined effect of bacteriocin and glycine and their application for food preservation, which may be helpful for future use in the food industry.

Molecular characterization of lysine 6-dehydrogenase from Achromobacter denitrificans

An inducible lysine 6-dehydrogenase (Lys 6-DH), which catalyzes the oxidative deamination of the 6-amino group of L-lysine in the presence of NAD(+), was purified to homogeneity from Achromobacter denitrificans, yielding a homodimeric protein of 80 kDa. The enzyme was specific for the substrate L-lysine and NAD(+) served as a cofactor. The dimeric enzyme associated into a hexamer in the presence of 10 mM L-lysine. The K(m) values for L-lysine and NAD(+) were 5.0 and 0.09 mM, respectively. The lys 6-dh gene was cloned and overexpressed in E. coli. The open reading frame was 1,107 nucleotides long and encoded a peptide containing 368 amino acids with 39,355 Da. The recombinant enzyme was purified to homogeneity and characterized. Enzyme activities and kinetic properties of the recombinant enzyme were almost the same as those of the endogenous enzyme obtained from A. denitrificans. Crystals of the enzyme were obtained using the hanging drop method.

Evaluation of pyrrolidonyl arylamidase for the identification of nonfermenting Gram-negative rods

To evaluate the activity of pyrrolidonyl arylamidase (PYR) for the differentiation and identification of nonfermenting gram negative rods (NFGNR), 293 isolates were tested. A 24 h culture of each test organism was prepared. From this a 108–109 cfu/mL suspension was added to 0.25 mL of sterile physiologic solution. A PYR disk was then added and the test was incubated for 30 minutes at 35–37°C, at environmental atmosphere. Reading was done by adding 1 drop of cinnamaldehyde reagent. Strains of Acinetobacter baumannii, Acinetobacter haemolyticus, Alcaligenes faecalis, Bergeyella zoohelcum, Bordetella bronchiseptica, Bordetella hinzii, Brevundimonas diminuta, Brevundimonas vesicularis, Brucella ovis, Brucella spp., Brucella suis, Burkholderia cepacia complex, Moraxella catarrhalis, Moraxella lacunata, Moraxella nonliquefaciens, Moraxella osloensis, Oligella ureolytica, Pseudomonas alcaligenes, Pseudomonas mendocina, Pseudomonas pseudoalcaligenes, Pseudomonas putida, Pseudomonas stutzeri, Pseudomonas Vb3, Psychrobacter phenylpyruvicus, and Stenotrophomonas maltophilia were PYR negative. On the other hand Achromobacter piechaudii, Achromobacter denitrificans, Achromobacter xylosoxidans, Burkholderia gladioli, Chryseobacterium gleum-indologenes, Comamonas testosroni, Cupriavidus pauculus, Delftia acidovorans, Elizabethkingia meningoseptica, Myroides spp., Ochrobactrum anthropi, Pseudomonas oryzihabitans, Ralstonia pickettii, Rhizobium radiobacter, Shewanella spp., Sphingobacterium multivorum, Sphingobacterium spiritivorum, and Weeksella virosa were PYR positive. Finally, Acinetobacter lwoffii, Pseudomonas aeruginosa, Pseudomonas fluorescens, Roseomonas spp., and Sphingomonas paucimobilis-parapaucimobilis were PYR variable. PYR testing should be considered as a useful tool to facilitate the identification of NFGNR.

Kerstersia gyiorum gen. nov., sp. nov., a novel Alcaligenes faecalis-like organism isolated from human clinical samples, and reclassification of Alcaligenes denitrificans Rüger and Tan 1983 as Achromobacter denitrificans comb. nov.

A polyphasic taxonomic study was performed on nine isolates recovered from various human clinical samples. Phenotypically, these isolates resembled Alcaligenes faecalis. Whole-cell protein analysis distinguished two different species, and this was confirmed by DNA-DNA hybridizations. Cellular fatty acid analysis and 16S rDNA sequence analysis indicated that these isolates were related to the genera Alcaligenes, Bordetella, Achromobacter and Pigmentiphaga and belonged to the family Alcaligenaceae. On the basis of the results of this study, the organisms were classified in a novel genus, Kerstersia gen. nov. This genus comprises one species, Kerstersia gyiorum sp. nov. (type strain LMG 5906(T)=API 184-2-84(T)=CCUG 47000(T)), and several unnamed isolates. The DNA G+C content of members of the genus Kerstersia is between 61.5 and 62.9 mol%. On the basis of previously published DNA-DNA hybridization results and data from chemotaxonomic studies, it is proposed that Alcaligenes denitrificans Rüger and Tan 1983 be reclassified as Achromobacter denitrificans comb. nov.