Assessing interactions, predicting function, and increasing degradation potential of a PAH-degrading bacterial consortium by effect of an inoculant strain.

A natural phenanthrene-degrading consortium CON was inoculated with an exogenous strain Sphingobium sp. (ex Sp. paucimobilis) 20006FA yielding the consortium called I-CON, in order to study ecological interactions into the bacterial community. DGGE and proteomic profiles and analyses by HTS (High-Throughput Sequencing) technologies demonstrated inoculant establishment and changes on CON composition. Inoculation increased degradation efficiency in I-CON and prevented intermediate HNA accumulation. This could be explained not only by the inoculation, but also by enrichment in Achromobacter genus at expense of a decrease in Klebsiella genus. After inoculation, cooperation between Sphingobium and Achromobacter genera were improved, thereby, some competition could have been generated, and as a consequence, species in minor proportion (cheaters), as Inquilinus sp. and Luteibacter sp., were not detected. Sequences of Sphingobium (corresponding to the inoculated strain) did not vary. PICRUSt predicted a network with bacterial phylotypes connected with enzymes, showing functional redundancy in the phenanthrene pathway, with exception of the first enzymes biphenyl-2,3-diol 1,2-dioxygenase and protocatechuate 4,5-dioxygenase that were only encoded in Sphingobium sp. This is the first report where a natural consortium that has been characterized by HTS technologies is inoculated with an exogenous strain in order to study competitiveness and interactions.

Optimization and characterization of a glycolipid produced by Achromobacter sp. to use in petroleum industries.

A biosurfactant, produced by Achromobacter sp. TMB1 is reported through this investigation having physiochemical properties useful for operational and remedial activities in petroleum industries. The strain isolated from soils of local petrol pumps when allowed to grow in glucose containing mineral salts media (MSM) in ambient environment that is, 30 °C and varying pH in between 5.5 and 7.2, showed surface tension reduction as low as 34.25 dyne cm-1 at an interval of 48-72 h. Taguchi experiment confirmed the contribution of glucose, yeast extracts, and NaNO3 concentration on biosurfactant production. FTIR and 1 H NMR analysis of culture supernatant obtained after acid precipitation and solvent extraction methods revealed the glycolipid nature of the extracted compounds. HR-LCMS study further revealed the presence of 10 different types of mono- and di-rhamnolipids congeners with the fatty acids carbon length C8-12 . The isolated biosurfactant shows functional stability in the temperature range 20-100 °C and pH range 2-12 while maintaining the structural integrity till 550 °C (TGA-DSC), strongly suggests its potential applications in petroleum industries.

Serendipitous crystallization and structure determination of bacterioferritin from Achromobacter.

Bacterioferritins (Bfrs) are ferritin-like molecules with a hollow spherical 24-mer complex design that are unique to bacterial and archaeal species. They play a critical role in storing iron(III) within the complex at concentrations much higher than the feasible solubility limits of iron(III), thus maintaining iron homeostasis within cells. Here, the crystal structure of bacterioferritin from Achromobacter (Ach Bfr) that crystallized serendipitously during a crystallization attempt of an unrelated mycobacterial protein is reported at 1.95 Šresolution. Notably, Fe atoms were bound to the structure along with a porphyrin ring sandwiched between the subunits of a dimer. Furthermore, the dinuclear ferroxidase center of Ach Bfr has only a single iron bound, in contrast to the two Fe atoms in other Bfrs. The structure of Ach Bfr clearly demonstrates the substitution of a glutamate residue, which is involved in the interaction with the second Fe atom, by a threonine and the consequent absence of another Fe atom there. The iron at the dinuclear center has a tetravalent coordination, while a second iron with a hexavalent coordination was found within the porphyrin ring, generating a heme moiety. Achromobacter spp. are known opportunistic pathogens; this structure enhances the current understanding of their iron metabolism and regulation, and importantly will be useful in the design of small-molecule inhibitors against this protein through a structure-guided approach.

Colonization study of gfp-tagged Achromobacter marplatensis strain in sugar beet.

This study details the introduction of a gfp marker into an endophytic bacterial strain (Achromobacter marplatensis strain 17, isolated from sugar beet) to monitor its colonization of sugar beet (Beta. vulgaris L.). Stability of the plasmid encoding the gfp was confirmed in vitro for at least 72 h of bacterial growth and after the colonization of tissues, under nonselective conditions. The colonization was observed using fluorescence microscopy and enumeration of culturable endophytes in inoculated sugar beet plants that grew for 10 or 20 days. gfp-Expressing strains were re-isolated from the inner tissues of surface-sterilized roots and stems of inoculated plants, and the survival of the Achromobacter marplatensis 17:gfp strain in plants 20 days after inoculation, even in the absence of selective pressure, suggests that it is good colonizer. These results also suggest that this strain could be a useful tool for the delivery of enzymes or other proteins into plants. In addition, the study highlights that sugar beet plants can be used effectively for detailed in vitro studies on the interactions between A. marplatensis strain 17 and its host, particularly if a gfp-tagged strain of the pathogen is used.

Purification and characterization of exopolysaccharide bioflocculant produced by heavy metal resistant Achromobacter xylosoxidans.

Optimization of process parameters enhanced bioflocculating activity of 'Achromobacter xylosoxidans strain TERI L1' from 75% to 83.3% in absence of heavy metals, which decreased to 73% in presence of multi-metals. 'TERI L1' could adsorb 90% of multi-metals when grown in presence of 1250 mg L(-1) Zn, 2 mg L(-1) Cd, 30 mg L(-1) Pb, 200 mg L(-1) Ni and 90 mg L(-1) Cu and could adsorb 1100 mg L(-1) of Pb when grown in presence of 1500 ppm lead nitrate. The bioflocculant was purified and characterized. Bioflocculant yield was 5 g L(-1). Fourier transform infrared spectrum indicated presence of carboxyl, hydroxyl, amino groups, typical of glycoprotein. Spectroscopic analysis of bioflocculant by nuclear magnetic resonance revealed that it is a glycoprotein. LC-MS analysis confirmed the bioflocculant as a carbohydrate hetero polymer. Bioflocculant was composed of 75% total sugar with 72.9% neutral sugar and 11.5% protein. Scanning Electron Micrography revealed effective flocculation of kaolin clay by purified exopolysaccharide bioflocculant.

Carbazole degradation in the soil microcosm by tropical bacterial strains

In a previous study, three bacterial strains isolated from tropical hydrocarbon-contaminated soils and phylogenetically identified as Achromobacter sp. strain SL1, Pseudomonas sp. strain SL4 and Microbacterium esteraromaticum strain SL6 displayed angular dioxygenation and mineralization of carbazole in batch cultures. In this study, the ability of these isolates to survive and enhance carbazole degradation in soil were tested in field-moist microcosms. Strain SL4 had the highest survival rate (1.8 x 107 cfu/g) after 30 days of incubation in sterilized soil, while there was a decrease in population density in native (unsterilized) soil when compared with the initial population. Gas chromatographic analysis after 30 days of incubation showed that in sterilized soil amended with carbazole (100 mg/kg), 66.96, 82.15 and 68.54% were degraded by strains SL1, SL4 and SL6, respectively, with rates of degradation of 0.093, 0.114 and 0.095 mg kg−1 h−1. The combination of the three isolates as inoculum in sterilized soil degraded 87.13% carbazole at a rate of 0.121 mg kg−1 h−1. In native soil amended with carbazole (100 mg/kg), 91.64, 87.29 and 89.13% were degraded by strains SL1, SL4 and SL6 after 30 days of incubation, with rates of degradation of 0.127, 0.121 and 0.124 mg kg−1 h−1, respectively. This study successfully established the survivability (> 106 cfu/g detected after 30 days) and carbazole-degrading ability of these bacterial strains in soil, and highlights the potential of these isolates as seed for the bioremediation of carbazole-impacted environments.

Classification of Achromobacter genogroups 2, 5, 7 and 14 as Achromobacter insuavis sp. nov., Achromobacter aegrifaciens sp. nov., Achromobacter anxifer sp. nov. and Achromobacter dolens sp. nov., respectively.

The phenotypic and genotypic characteristics of seventeen Achromobacter strains representing MLST genogroups 2, 5, 7 and 14 were examined. Although genogroup 2 and 14 strains shared a DNA-DNA hybridization level of about 70%, the type strains of both genogroups differed in numerous biochemical characteristics and all genogroup 2 and 14 strains could by distinguished by nitrite reduction, denitrification and growth on acetamide. Given the MLST sequence divergence which identified genogroups 2 and 14 as clearly distinct populations, the availability of nrdA sequence analysis as a single locus identification tool for all Achromobacter species and genogroups, and the differential phenotypic characteristics, we propose to formally classify Achromobacter genogroups 2, 5, 7 and 14 as four novel Achromobacter species for which we propose the names Achromobacter insuavis sp. nov. (with strain LMG 26845(T) [=CCUG 62426(T)] as the type strain), Achromobacter aegrifaciens sp. nov. (with strain LMG 26852(T) [=CCUG 62438(T)] as the type strain), Achromobacter anxifer sp. nov. (with strain LMG 26857(T) [=CCUG 62444(T)] as the type strain), and Achromobacter dolens sp. nov. (with strain LMG 26840(T) [=CCUG 62421(T)] as the type strain).

Rapid determination of quinoline and 2-hydroxyquinoline in quinoline biodegradation process by tri-wavelength UV/Vis spectroscopy.

For the present study, a tri-wavelength UV/Vis spectrophotometric method for rapid determination of quinoline (Q) and 2-hydroxyquinoline (HQ) during Q biodegradation was developed. Based on the spectral measurements at 289 nm (the isosbestic point of Q and HQ), 326 and 380 nm, the spectral interference of extracellular polymeric substances (EPS) in the process samples could be minimized, and the amounts of Q and HQ could be simultaneously quantified. Our results indicated that the relative standard deviations in the repeatability tests were 2.7 and 1.7% for Q and HQ, respectively. The method validation was conducted by comparing the data obtained using the present method with those generated from high performance liquid chromatography (HPLC). The same set of samples from Q biodegradation process was used. The relative differences between the two methods were within 10%. In conclusion, the present method is simple, rapid, and suitable for the investigation in Q biodegradation processes.

Isolation and characterization of two new microbial strains capable of degradation of the naturally occurring organophosphonate - ciliatine.

Air-born mixed fungal and bacterial culture capable of complete degradation of ciliatine was isolated. The utilization of the natural organophosphonate proceeded in the phosphate independent manner. Enzymatic activity involved in ciliatine degradation studied in the fungal cell-free extract proved to be distinct from bacterial pathway described before.