Showing papers on "Arthrobacter published in 2015"

Genomic and phenotypic insights into the ecology of Arthrobacter from Antarctic soils

Abstract: Members of the bacterial genus Arthrobacter are both readily cultured and commonly identified in Antarctic soil communities. Currently, relatively little is known about the physiological traits that allow these bacteria to survive in the harsh Antarctic soil environment. The aim of this study is to investigate if Antarctic strains of Arthrobacter owe their resilience to substantial genomic changes compared to Arthrobacter spp. isolated from temperate soil environments. Quantitative PCR-based analysis revealed that up to 4% of the soil bacterial communities were comprised of Arthrobacter spp. at four locations in the Ross Sea Region. Genome analysis of the seven Antarctic Arthrobacter isolates revealed several features that are commonly observed in psychrophilic/psychrotolerant bacteria. These include genes primarily associated with sigma factors, signal transduction pathways, the carotenoid biosynthesis pathway and genes induced by cold-shock, oxidative and osmotic stresses. However, these genes were also identified in genomes of seven temperate Arthrobacter spp., suggesting that these mechanisms are beneficial for growth and survival in a range of soil environments. Phenotypic characterisation revealed that Antarctic Arthrobacter isolates demonstrate significantly lower metabolic versatility and a narrower salinity tolerance range compared to temperate Arthrobacter species. Comparative analyses also revealed fewer protein-coding sequences and a significant decrease in genes associated with transcription and carbohydrate transport and metabolism in four of the seven Antarctic Arthrobacter isolates. Notwithstanding genome incompleteness, these differences together with the decreased metabolic versatility are indicative of genome content scaling. The genomes of the seven Antarctic Arthrobacter isolates contained several features that may be beneficial for growth and survival in the Antarctic soil environment, although these features were not unique to the Antarctic isolates. These genome sequences allow further investigations into the expression of physiological traits that enable survival under extreme conditions and, more importantly, into the ability of these bacteria to respond to future perturbations including climate change and human impacts.

Phosphate solubilizing and indole-3-acetic acid producing bacteria from the soil of Garhwal Himalaya aimed to improve the growth of rice.

Abstract: In the present study, soil bacteria from rainfed agriculture field of Garhwal Himalaya, just prior to sowing of summer crop, were isolated and initially tested for solubilization of inorganic phosphate, production of indole acetic acid (IAA) and siderophore. Two bacterial isolates, having efficient P- solubilizing activity in solid medium, were identified using 16S rRNA sequence analysis as Pseudomonas koreensis strainYB1 Arthrobacter nitroguajacolicus strainYB3 and three bacterial isolates, producing high amount of IAA in liquid medium, were identified as Klebsiella oxytoca strainYB2 and two strain of Arthrobacter nitroguajacolicus, strainYB4 and YB5, respectively. In culture medium supplemented with L-Tryptophan, Klebsiella oxytoca produced high amount of IAA (337.44 μg l(-1)). The selected five bacterial strains were further tested for tricalcium phosphate (TCP) solubilizing abilities at three different incubation temperature viz., 4 degrees C, 10 degrees C and 28 degrees C, under in vitro conditions. At 28 degrees C, three bacterial strains Pseudomonas koreensis, Arthrobacter nitroguajacolicus strainYB4 and Klebsiella oxytoca solubilized the phosphate efficiently. At 10 degrees C only two strains, Pseudomonas koreensis and Arthrobacter nitroguajacolicus strainYB4 solubilized phosphate efficiently as compared to other strains. These five bacterial strains were tested for nitrogen, catalase activity, starch and cellulose hydrolysis as well as growth promotion activity on rice, under controlled conditions. All the five bacterial strains efficiently increased the biomass and phosphorus uptake in Swama and Swarna sub1 varieties of rice.

Bacterial-assisted cadmium phytoremediation by ocimum gratissimum l. in polluted agricultural soil: a field trial experiment

Abstract: A field study of cadmium phytoremediation by Ocimum gratissimum L. and the potential enhancement by two cadmium-resistant bacteria, Ralstonia sp. TISTR 2219 and Arthrobacter sp. TISTR 2220, were explored in a cadmium-polluted agricultural area. The results demonstrated the ability of one of the bacterial strains to promote cadmium accumulation in O. gratissimum L. planted in soil with cadmium concentrations till 65.2 mg kg−1. After transplantation in contaminated soil for 2 months, soil inoculation with Arthrobacter sp. enhanced cadmium accumulation in the roots, above-ground tissues, and whole plant of O. gratissimum L. by 1.2-fold, 1.4-fold, and 1.1-fold, respectively, compared with the untreated control. The presence of Arthrobacter sp. in soil facilitated cadmium phytoremediation in O. gratissimum L. similar to that of an EDTA application. Seeds of O. gratissimum L. grown in polluted soil contained undetectable to negligible concentrations of cadmium. Significant increases in the bioconcentration and translocation factors of O. gratissimum L. were observed in Arthrobacter sp.-inoculated plants at only 2 months post-transplant compared with the uninoculated control. The highest percentage of cadmium removal was found in soil used to cultivate EDTA-treated O. gratissimum L., followed by an Arthrobacter sp.-inoculated plant. Our findings suggest that the synergistic use of Arthrobacter sp. with O. gratissimum L., an essential oil-producing crop, could be a feasible economic and environmental option for the reclamation of cadmium-polluted areas.

Gene expression of an arthrobacter in surfactant-enhanced biodegradation of a hydrophobic organic compound.

Abstract: Surfactants can affect the biodegradation process and the fate of hydrophobic organic compounds (HOCs) in the environment. Previous studies have shown that surfactants can enhance the biodegradation of HOCs by increasing cell surface hydrophobicity (CSH) and membrane fluidity. In this study, we took this work one step further by investigating the expression levels of three genes of Arthrobacter sp. SA02 in the biodegradation of phenanthrene as a typical HOC at different concentrations of sodium dodecyl benzenesulfonate (SDBS), which is a widely used surfactant. The Δ9 fatty acid desaturase gene codes for Δ9 fatty acid desaturase, which can convert saturated fatty acid to its unsaturated form. The ring-hydroxylating dioxygenase (RHDase) and the 1-hydroxyl-2-naphthoate dioxygenase (1H2Nase) genes code for the RHDase and 1H2Nase enzymes, respectively, which play a key role in decomposing doubly hydroxylated aromatic compounds. The results show that these three genes were upregulated in the presence of SDBS. ...

Most Hydrocarbonoclastic Bacteria in the Total Environment are Diazotrophic, which Highlights Their Value in the Bioremediation of Hydrocarbon Contaminants

Abstract: Eighty-two out of the 100 hydrocarbonoclastic bacterial species that have been already isolated from oil-contaminated Kuwaiti sites, characterized by 16S rRNA nucleotide sequencing, and preserved in our private culture collection, grew successfully in a mineral medium free of any nitrogenous compounds with oil vapor as the sole carbon source. Fifteen out of these 82 species were selected for further study based on the predominance of most of the isolates in their specific sites. All of these species tested positive for nitrogenase using the acetylene reduction reaction. They belonged to the genera Agrobacterium, Sphingomonas, and Pseudomonas from oily desert soil and Nesiotobacter, Nitratireductor, Acinetobacter, Alcanivorax, Arthrobacter, Marinobacter, Pseudoalteromonas, Vibrio, Diatzia, Mycobacterium, and Microbacterium from the Arabian/Persian Gulf water body. A PCR-DGGE-based sequencing analysis of nifH genes revealed the common occurrence of the corresponding genes among all the strains tested. The tested species also grew well and consumed crude oil effectively in NaNO3 -containing medium with and without nitrogen gas in the top space. On the other hand, these bacteria only grew and consumed crude oil in the NaNO3 -free medium when the top space gas contained nitrogen. We concluded that most hydrocarbonoclastic bacteria are diazotrophic, which allows for their wide distribution in the total environment. Therefore, these bacteria are useful for the cost-effective, environmentally friendly bioremediation of hydrocarbon contaminants.

An optimized enrichment technique for the isolation of Arthrobacter bacteriophage species from soil sample isolates.

Abstract: Bacteriophage isolation from environmental samples has been performed for decades using principles set forth by pioneers in microbiology. The isolation of phages infecting Arthrobacter hosts has been limited, perhaps due to the low success rate of many previous isolation techniques, resulting in an underrepresented group of Arthrobacter phages available for study. The enrichment technique described here, unlike many others, uses a filtered extract free of contaminating bacteria as the base for indicator bacteria growth, Arthrobactersp. KY3901, specifically. By first removing soil bacteria the target phages are not hindered by competition with native soil bacteria present in initial soil samples. This enrichment method has resulted in dozens of unique phages from several different soil types and even produced different types of phages from the same enriched soil sample isolate. The use of this procedure can be expanded to most nutrient rich aerobic media for the isolation of phages in a vast diversity of interesting host bacteria.

Comparative genome analysis reveals the molecular basis of nicotine degradation and survival capacities of Arthrobacter

Abstract: Arthrobacter is one of the most prevalent genera of nicotine-degrading bacteria; however, studies of nicotine degradation in Arthrobacter species remain at the plasmid level (plasmid pAO1). Here, we report the bioinformatic analysis of a nicotine-degrading Arthrobacter aurescens M2012083, and show that the moeB and mogA genes that are essential for nicotine degradation in Arthrobacter are absent from plasmid pAO1. Homologues of all the nicotine degradation-related genes of plasmid pAO1 were found to be located on a 68,622-bp DNA segment (nic segment-1) in the M2012083 genome, showing 98.1% nucleotide acid sequence identity to the 69,252-bp nic segment of plasmid pAO1. However, the rest sequence of plasmid pAO1 other than the nic segment shows no significant similarity to the genome sequence of strain M2012083. Taken together, our data suggest that the nicotine degradation-related genes of strain M2012083 are located on the chromosome or a plasmid other than pAO1. Based on the genomic sequence comparison of strain M2012083 and six other Arthrobacter strains, we have identified 17 σ70 transcription factors reported to be involved in stress responses and 109 genes involved in environmental adaptability of strain M2012083. These results reveal the molecular basis of nicotine degradation and survival capacities of Arthrobacter species.

Arthroamide, a Cyclic Depsipeptide with Quorum Sensing Inhibitory Activity from Arthrobacter sp.

Abstract: Nonfilamentous actinobacteria have been less studied as secondary metabolite producers than their filamentous counterparts such as Streptomyces. From our collection of nonfilamentous actinobacteria isolated from sandstone, an Arthrobacter strain was found to produce a new cyclic peptide arthroamide (1) together with the known compound turnagainolide A (2). These compounds inhibited the quorum sensing signaling of Staphylococcus aureus in the submicromolar to micromolar range.

Biodegradation of pentachloronitrobenzene by Arthrobacter nicotianae DH19

Abstract: UNLABELLED A pentachloronitrobenzene (PCNB)-degrading bacterial strain was identified as Arthrobacter nicotianae based on morphological, physiological and biochemical tests, and 16S rRNA gene sequences analysis. The strain could grow on mineral salt medium (MSM) containing PCNB as the sole carbon source. Under optimal conditions (pH 6·85, 30°C and inoculum biomass amount of 1·45 g l(-1) ), more than 90% residues of PCNB were degraded by strain DH19 within 7 days. Strain DH19 could efficiently degrade dichlorodiphenyl trichloroethane, hexachlorocyclohexane, cypermethrin and cyhalothrin. Metabolites from PCNB degradation were identified by using gas chromatography (GC) coupled with triple quadrupole mass spectrometry. A possible degradation pathway for PCNB was deduced. This is the first report of PCNB-degrading strain DH19 isolated from the rhizospheric soil. Therefore, strain DH19 could potentially be employed in bioremediation of PCNB. SIGNIFICANCE AND IMPACT OF THE STUDY The degradation of pentachloronitrobenzene (PCNB) by an individual bacterial strain is being reported for the first time. The efficient PCNB-degrading strain DH19 was isolated from ginseng rhizosphere soil and identified as Arthrobacter nicotianae. The strain could utilize PCNB as the sole carbon source for growth and degradation. In addition, strain DH19 could efficiently degrade dichlorodiphenyl trichloroethane, hexachlorocyclohexane, cypermethrin and cyhalothrin. Five metabolites from PCNB degradation were identified, and a possible degradation pathway was deduced. The results suggest that A. nicotianae DH19 has great potential for the bioremediation of PCNB-contaminated environments.

Green Synthesis of Gold Nanoparticles by a Metal Resistant Arthrobacter nitroguajacolicus Isolated From Gold Mine

Abstract: Biosynthesis of gold nanoparticles would benefit from the development of clean, nontoxic and environmentally acceptable procedures concerning microorganisms from bacteria to fungi and even algae. Actinobacteria are soil bacteria which have the enormous ability as biotechnological tools. In this paper, we reported the biosynthesis of gold nanoparticles by a member of Arthrobacter genus isolated from Andaliyan gold mine in north-west of Iran. This metal resistance strain obtained from an acidophilic region $({\sim} {\rm pH}\ 5.6)$ . The UV-vis and XRD spectra of the aqueous medium containing the strain and 1 mM HAuCl $_{4}$ for 24 h, demonstrated the formation of gold nanoparticles. TEM micrographs showed intra-extracellular production of gold nanoparticles with spherical shape and average size of 40 nm. The result of morphological and molecular tests revealed that the isolate was belonged to Atrhrobacter and has 100% similarity in 16SrRNA gene sequences to Arthrobacter nitroguajacolicus.

Arthrobacter endophyticus sp. nov., an endophytic actinobacterium isolated from root of Salsola affinis C. A. Mey.

Abstract: A Gram-staining-positive, white-coloured, aerobic, non-motile, catalase-positive and oxidase-negative, endophytic actinobacterium, designated strain EGI 6500322(T), was isolated from the surface-sterilized root of the halophyte Salsola affinis C. A. Mey collected from Urumqi, Xinjiang province, north-west China. Growth occurred at 5-35 °C (optimum 25-30 °C), at pH 5-10 (optimum pH 7-8) and with 0-13% NaCl (w/v) (optimum 0-5%). The predominant menaquinone was MK-9 (93.1%). The major cellular fatty acids were anteiso-C15:0 (49.5%) and iso-C15:0 (15.1%). The cell-wall peptidoglycan contained lysine, alanine and glutamic acid. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, two unknown phospholipids and one unknown glycolipid. The DNA G+C content of strain EGI 6500322(T) was 62.0 mol%. Based on 16S rRNA gene sequence analysis, the nearest phylogenetic neighbours of strain EGI 6500322(T) were identified as Arthrobacter ardleyensis DSM 17432(T) (98.38%) and Arthrobacter bergerei DSM 16367(T (98.37%). The DNA-DNA relatedness between strain EGI 6500322(T) and Arthrobacter ardleyensis DSM 17432(T) and Arthrobacter bergerei DSM 16367(T) was 53.4 ± 4.1% and 30.5 ± 1.7%, respectively. On the basis of the phylogenetic analysis, chemotaxonomic data, physiological characteristics and DNA-DNA hybridization data, strain EGI 6500322(T) should represent a novel species of the genus Arthrobacter, for which the name Arthrobacter endophyticus sp. nov. is proposed. The type strain is EGI 6500322(T) ( = CTC 29490(T) = JCM 30091(T)).

Biodegradation of 2,4-dinitrotoluene (DNT) by Arthrobacter sp. K1 isolated from a crude oil contaminated soil

Abstract: Laboratory experiments were performed to characterize and identify 2,4-dinitrotoluene (DNT)-degrading bacterial strains isolated from crude oil contaminated soil from a landfill dump site of a petroleum refinery in Mersin, Turkey. Fluorescent in situ hybridization (FISH) with dntAa probes encoding 2,4-DNT dioxygenase was used to detect 2,4-DNT-degrading bacteria. The direct FISH analysis of soil samples collected from a petroleum refinery showed very weak signals. Therefore, a selective enrichment culture technique using 2,4-DNT as the sole carbon source was then used to isolate DNT degrading bacteria. Following the culture enrichment procedure, the hybridization signals improved significantly in the isolated bacterial strains. Based on 16S rRNA sequences, the bacteria isolated from the soil samples were identified as Arthrobacter sp. Results from the batch biodegradation experiments indicate that the biodegradation rates of 2,4-DNT with this strain were highly dependent on environmental conditions such as pH and temperature, with optimum conditions obtained at 30 °C and pH ∼7. A first-order kinetic model was able to accurately describe 2,4-DNT degradation rates under different environmental conditions (e.g., pH). The ability of Arthrobacter sp. for degrading 2,4-DNT was found to be plasmid-mediated through curing experiments. The size of the plasmid involved, referred to as pArK1, was estimated to be about 8.1 kb.

Production of biosurfactants by Arthrobacter sp. N3, a hydrocarbon degrading bacterium

Abstract: Different screening methods, such as emulsification capacity and oil spreading assays, hydrocarbon overlay agar and modified drop collapse methods were used to detect biosurfactant production by hydrocarbon degrading Arthrobacter sp N3 strain. It was indicated that oil spreading assay was the most reliable method to detect biosurfactant production. To investigate biosurfactant production, batch cultivation of Arthrobacter sp N3 was carried out in a fermenter with complex nutrient medium supplemented by sunflower oil as a carbon source. The highest oil displacement activity was achieved when Arthrobacter sp N3 strain was cultivated in two stages (with aeration for cell production and without aeration for biosurfactant synthesis). Then, two forms of the biosurfactant (crude preparation and partially purified biosurfactant) were recovered from the culture liquid. Furthermore, the biosurfactant produced by Arthrobacter sp N3 strain was analyzed by thin layer chromatography and it was estimated that even a few compounds have surface activity. The effect of temperature and pH on biosurfactant activity was also studied. It was observed that no appreciable changes in biosurfactant activity occurred at temperature and pH values ranges of 4–125 oC and 5–10, respectively.

Bioremediation of Atmospheric Hydrocarbons via Bacteria Naturally Associated with Leaves of Higher Plants.

Abstract: Bacteria associated with leaves of sixteen cultivated and wild plant species from all over Kuwait were analyzed by a culture-independent approach. This technique depended on partial sequencing of 16S rDNA regions in total genomic DNA from the bacterial consortia and comparing the resulting sequences with those in the GenBank database. To release bacterial cells from leaves, tough methods such as sonication co-released too much leaf chloroplasts whose DNA interfered with the bacterial DNA. A more satisfactory bacterial release with a minimum of chloroplast co-release was done by gently rubbing the leaf surfaces with soft tooth brushes in phosphate buffer. The leaves of all plant species harbored on their surfaces bacterial communities predominated by hydrocarbonoclastic (hydrocarbon-utilizing) bacterial genera. Leaves of 6 representative plants brought about in the laboratory effective removal of volatile hydrocarbons in sealed microcosms. Each individual plant species had a unique bacterial community structure. Collectively, the phyllospheric microflora on the studied plants comprised the genera Flavobacterium, Halomonas, Arthrobacter, Marinobacter, Neisseria, Ralstonia, Ochrobactrum. Exiguobacterium, Planomicrobium, Propionibacterium, Kocuria, Rhodococcus and Stenotrophomonas. This community structure was dramatically different from the structure we determined earlier for the same plants using the culture-dependent approach, although in both cases, hydrocarbonoclastic bacteria were frequent.

Characterization of an exo-inulinase from Arthrobacter: A novel NaCl-tolerant exo-inulinase with high molecular mass

Abstract: A glycoside hydrolase family 32 exo-inulinase gene was cloned from Arthrobacter sp HJ7 isolated from saline soil located in Heijing town The gene encodes an 892-residue polypeptide with a calculated mass of 951 kDa and a high total frequency of amino acid residues G, A, and V (300%) Escherichia coli BL21 (DE3) cells were used as hosts to express the exo-inulinase gene The recombinant exo-inulinase (rInuAHJ7) showed an apparently maximal activity at pH 50–55 and 40–45°C The addition of 10 and 100 mM Zn2+ and Pb2+ had little or no effect on the enzyme activity rInuAHJ7 exhibited good salt tolerance, retaining more than 98% inulinase activity at a concentration of 30%–200% (w/v) NaCl Fructose was the main product of inulin, levan, and Jerusalem artichoke tubers hydrolyzed by the enzyme The present study is the first to report the identification and characterization of an Arthrobacter sp exo-inulinase showing a high molecular mass of 951 kDa and NaCl tolerance These results suggest that the

Identification of a recombinant inulin fructotransferase (difructose dianhydride III forming) from Arthrobacter sp. 161MFSha2.1 with high specific activity and remarkable thermostability.

Abstract: Difructose dianhydride III (DFA III) is a functional carbohydrate produced from inulin by inulin fructotransferase (IFTase, EC 4.2.2.18). In this work, an IFTase gene from Arthrobacter sp. 161MFSha2.1 was cloned and expressed in Escherachia coli. The recombinant enzyme was purified by metal affinity chromatography. It showed significant inulin hydrolysis activity, and the produced main product from inulin was determined as DFA III by nuclear magnetic resonance analysis. The molecular mass of the purified protein was calculated to be 43 and 125 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration, respectively, suggesting the native enzyme might be a homotrimer. The recombinant enzyme showed maximal activity as 2391 units/mg at pH 6.5 and 55 °C. It displayed the highest thermostability among previously reported IFTases (DFA III forming) and was stable up to 80 °C for 4 h of incubation. The smallest substrate was determined as nystose. The conversion ratio of inulin to DFA III reached 81% when 100 g/L inulin was catalyzed by 80 nM recombinant enzyme for 20 min at pH 6.5 and 55 °C. All of these data indicated that the IFTase (DFA III forming) from Arthrobacter sp. 161MFSha2.1 had great potential for industrial DFA III production.

Isolation and characterization of culturable bacteria from bulk soil samples and the rhizosphere of arid-adapted Tylosema esculentum (Burchell). A. Schreiber (Marama bean) in Namibia

Abstract: Plant growth promoting (PGP) bacteria are microorganisms living in association with plants. PGP bacteria have various physiological activities that they perform which are beneficial to plants. For example, phosphate solubilisation, nitrogen fixation, phytostimulation and formation of siderophores. The aim of this investigation was to determine the diversity of PGP bacteria and to characterise them for possible promotion of plant growth from the rhizosphere of Tylosema esculentum , a nutritious arid adapted legume. For that purpose, in this study, bacteria were isolated from marama bean rhizosphere and bulk soil. The bacteria were screened for their ability to solubilise phosphates, for aminocyclopropane-1-carboxylate (ACC) deaminase activity, production of catalase, hydrogen cyanide, ammonia and protease activity. Efficiency of phosphate solubilising activity by bacteria was determined by phosphate solubilisation index. DNA was extracted from bacterial cultures and used to obtain 16S rDNA amplicons for bacterial molecular identification. A total of eight bacterial strains were isolated from the rhizosphere and 19 strains from bulk soil with potential plant growth promoting traits. The 27 bacterial isolates showed phosphate solubilising activity and five of the isolates had a solubilisation index of at least 6. A total of 23 isolates showed ACC deaminase activity. Hydrogen cyanide was produced by 16 isolates; 26 isolates had catalase activity, 23 isolates showed protease activity and all the isolates produced ammonia. The identified genera include Bacillus, Raoultella, Klebsiella, Acinetobacter, Arthrobacter, Kosakonia and Burkholderia . From this study, we conclude that there is a community of bacteria living in T. esculentum rhizosphere and proposed that in future these native bacterial strains can be used as biofertilisers for this arid agro-ecological area after verifying their suitability for inoculum development. Key words: Rhizobacteria, plant growth promoting bacteria, Kosakonia, Burkholderia. Abbreviation: PGP, Plant growth promoting.

Variation of lipase, catalase and dehydrogenase activities during bioremediation of crude oil polluted soil.

Abstract: Crude oil pollution pervades the communities of the Niger Delta region of Nigeria. The present study examines the changes in lipase, catalase and dehydrogenase activities in crude oil polluted soils remediated with arthrobacter and bacillus species isolated from a crude oil polluted soil in Ikarama-Okordia community of Bayelsa State, Nigeria. A total of ten polythene bags containing 10kg soil were used. The experimental control (natural attenuation), remediated A ( arthrobacter species bioaugmented) and remediated B ( bacillus species bioaugmented) had three polythene bags polluted with 100, 200 and 400ml crude oil respectively and one unpolluted polythene bag (control). Remediation lasted for 90days and analysis was carried out every 30days. The results showed a significant (p˂0.05) variation in the activities of the enzymes studied. Lipase activity increased as the volume of crude oil (contaminant) increased relative to time, however, the increment was more pronounced in the soil samples remediated with arthrobacter species than bacillus species. In all the soils (irrespective of the volume of contaminant), it was observed that there was a significant reduction in the activity of catalase between the unremediated (undergoing natural attenuation) and remediated sites ( arthrobacter and bacillus species) from the unpolluted soil (control); this reduction was pronounced in the unremediated soil and the soil remediated with bacillus species. However, as bioremediation proceeded from days 0 to 90, there was resurgence in catalase activity especially in the soils remediated with arthrobacter species. Interestingly, dehydrogenase activity reduced relative to time in all the soil samples. This study concludes that crude oil contamination in soil has adverse effects on the activities of lipase, catalase and dehydrogenase; however, microorganisms in polluted soils use their biochemical machinery including enzymes to degrade pollutants. KEYWORDS : Lipase, Catalase, Dehydrogenase, Bioremediation, Bacillus species, Arthrobacter species

Detoxification of Mercury by Bacteria Using Crude Glycerol from Biodiesel as a Carbon Source

Abstract: Bacteria that harbor the mer operon in their genome are able to enzymatically reduce mercury (II) to the volatile form of mercury Hg (0). Detoxification of contaminated waste by using these bacteria may be an alternative to conventional methods for mercury removal. Residual glycerol from the biodiesel industry can be used as a carbon source to accelerate the process. This work shows for the first time the feasibility of using residual glycerol as a carbon source for Hg removal by bacteria prospected from contaminated environments. Eight bacterial isolates were able to remove mercury and degrade glycerol in mineral medium and residual glycerol. Mercury removal was monitored by atomic absorption spectroscopy and glycerol degradation by high performance liquid chromatography. The best results of mercury removal and glycerol degradation were obtained using isolates of Serratia marcescens M25C (85 and 100 %), Klebsiella pneumoniae PLB (90 and 100 %), Klebsiella oxytoca (90 and 100 %), and Arthrobacter sp. U3 (80 and 75 %), with addition of 0.5 g L−1 yeast extract. The Arthrobacter sp. U3 isolate is common in soils and has proven to be a promising candidate for environment applications due to its low pathogenicity and higher Hg removal and glycerol degradation rates.

Mineralization of melamine and cyanuric acid as sole nitrogen source by newly isolated Arthrobacter spp. using a soil-charcoal perfusion method.

Abstract: Melamine belongs to the s-triazine family, and industrially used as raw product in many ways all over the world. Melamine has been reported for human harmful effects and detected from some crops, soil and water. To remove melamine from the polluted environment, the efficient melamine-mineralizing microorganisms have been needed. We newly isolated three melamine-degrading bacteria from the same upland soil sample using soil–charcoal perfusion method. These bacteria were classified as Arthrobacter sp. MCO, Arthrobacter sp. CSP and Microbacterium sp. ZEL by 16S rRNA genes sequencing analysis. Both Arthrobacter species completely degraded melamine within 2 days, and consumed melamine as a sole nitrogen source. Both strains also grew in cyanuric acid as sole nitrogen source, and released small quantities of ammonium ions. These strains are the first identified bacteria that can mineralize both melamine and cyanuric acid as sole initial nitrogen source in Arthrobacter sp. Although ammeline and ammelide intermediates were detected, these strains possess none of the known genes encoding melamine degrading enzymes. Since the Arthrobacter strains also degraded melamine in a high pH liquid medium, they present as potential bioremediation agents in melamine-polluted environments.

Arthrobacter nanjingensis sp. nov., a mineral-weathering bacterium isolated from forest soil.

Abstract: A Gram-stain-positive, non-motile, rod- or coccoid-shaped actinobacterium, designated strain A33T, was isolated from a forest soil sample from Nanjing, Jiangsu Province, PR China. The strain grew optimally at 30 °C, pH 7.0 and with 3 % NaCl (w/v). Phylogenetic analysis of the strain, based on 16S rRNA gene sequences, showed that it was most closely related to Arthrobacter woluwensis (98.4 % sequence similarity), Arthrobacter humicola (97.5 %), Arthrobacter globiformis (97.4 %), Arthrobacter oryzae (97.3 %) and Arthrobacter cupressi (97.0 %). The major cellular fatty acids were anteiso-C15 : 0, anteiso-C17 : 0 and iso-C15 : 0; MK-9(H2) was the predominant respiratory quinone. The polar lipids comprised diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and three glycolipids. Cell-wall analysis revealed that the peptidoglycan type was A3α, based on l-lysine-l-alanine; the cell-wall sugars were galactose and mannose. The genomic G+C content of strain A33T was 66.8 mol%. The low DNA–DNA relatedness values between strain A33T and recognized species of the genus Arthrobacter and many phenotypic properties supported the classification of strain A33T as a representative of a novel species of the genus Arthrobacter , for which the name Arthrobacter nanjingensis sp. nov. is proposed. The type strain is A33T ( = CCTCC AB 2014069T = DSM 28237T).

Bioinformatics-based molecular classification of Arthrobacter plasmids

Abstract: The omnipresence of Arthrobacter species in polluted and toxic soils indicates their great potential in environmental biotechnologies, but practical applications of these bacteria are scarce mainly due to the availability of useful genetic engineering tools. Although many fully sequenced Arthrobacter genomes have been deposited in GenBank, little is known about the biology of their plasmids, especially the core functions: replication and partition. In this study the available Arthrobacter plasmid sequences were analyzed in order to identify their putative replication origin. At least the oris from the cryptic plasmids pXZ10142, pCG1, and pBL1 appear to work in this genus. Based on ParA homolog sequences, the Arthrobacter specific plasmids were classified into 4 clades. Iteron-like sequences were identified on most of the plasmids, indicating the position of the putative Arthrobacter specific oris. Although attempts were made to identify the core gene set required for plasmid replication in this genus, it was not possible. The plasmid proteomes showed a rather low similarity.

Arthrobacter with aerobic denitrification capability and application thereof

Abstract: The invention discloses an arthrobacter with aerobic denitrification capability and application thereof and belongs to the technical field of microorganism application. The arthrobacter DYS3-4 with aerobic denitrification ability is preserved in the China Center for Type Culture Collection, the preservation date is 29th, April, 2015 and the preservation number is CCTCC M 2015 264. The arthrobacter DYS3-4 can be applied to nitrogenous effluent biological denitrification, mariculture nitrite removal, freshwater aquaculture nitrite removal and low temperature denitrification microorganism preparation. Under an aerobiotic condition, the nitrate and the nitrite in the water environment can be rapidly and effectively removed. The arthrobacter growth temperature scope is wide, the denitrification effect at the temperature of 10-35 DEG C is good, and the arthrobacter has good application prospect in the nitrogenous effluent biological denitrification and the freshwater aquaculture nitrite removal.

Arthrobacter and application thereof

Abstract: The invention provides an arthrobacter and an application thereof. The arthrobacter is YC-RL1 collected with the serial number of CGMCC No.10611 and can be used for simultaneously degrading a mixture composed of 100mg/L naphthalene, 100mg/L fluorene, 100mg/L biphenol, 100mg/L 1, 2, 3, 4-tetrachlorobenzene and 100mg/L p-nitrophenol in an inorganic salt within 4 days. The arthrobacter has a relatively-wide tolerance range for salt ion concentration and can be used for simultaneously degrading a mixture composed of five 100mg/L compounds in an inorganic salt ion culture medium with the NaCl concentration of 0-60g/L within 5 days. YC-RL1 can be applied to biological remediation of an environment polluted by naphthalene, fluorene, biphenol, 1, 2, 3, 4-tetrachlorobenzene and p-nitrophenol and an environment simultaneously polluted by various pollutants, also has a favorable application potential for high-salt industrial production wastewater treatment of the pollutants and also has a relatively-high economic value and a relatively-good application prospect.

Selection of Microbes and Conditions that Induced Bio-Cracking of Branched Hydrocarbon Squalane

Abstract: Biological oil hydrocarbons degradation is a complicated process, influenced by hydrocarbons properties, microorganisms and environmental conditions. The aim of this work was to select microbial strain, capable of degrading heavy branched hydrocarbons for further application in environment remediation and bio-cracking. Also, it was necessary to select optimal conditions (temperature, pH, concentration and etc.) for selected microbial strain degrading heavy branched hydrocarbons. Since crude oil and its products are mixtures of various hydrocarbons, at the first step of selection the ability of the strains to degrade individual hydrocarbons was investigated. Squalane was used as a test substrate. 10 microbial cultures belonging to genus Arthrobacter and obtained from culture collection of JSC “Biocentras” were used for the investigations. Gas chromatography analysis revealed that Arthrobacter sp NJ5 strain had the highest effectiveness (67%) in degradation of heavy branched oil hydrocarbon (Squalane) to shorter chain intermediates. So, Arthrobacter sp NJ5 could be applied in bio-cracking. For the application in industry, more detailed analyses are needed.