Silvimonas soli sp. nov., a new member of Chromobacteriaceae isolated from soil in Norrbyskär island, Sweden.

A novel bacterial species is described that was isolated from the soil of Norrbyskär island (Sweden). This Gram-negative, facultatively anaerobic and motile rod, designated 17-6T, was classified in the family Chromobacteriaceae, class Betaproteobacteria, and further characterized by a polyphasic approach. Comparative 16S rRNA gene analysis revealed the potential species novelty of the strain, with Silvimonas terrae (98.20 % similarity) and Silvimonas amylolytica (98.13 %) being its closest type strains. The phylogenetic novelty of the isolate at the level of species was confirmed using phylogenetic analyses based on the whole genome: average nucleotide identity values ranged from 79 to 81 %, average amino acid identity values from 75 to 81 % and percentage of conserved proteins values from 69-81 % with the members of genera Silvimonas and Amantichitinum. On the basis of phenotypic, phylogenetic, functional and genotypic analyses, we propose the isolate as the type strain of a novel species within the genus Silvimonas with the designation Silvimonas soli 17-6T (=DSM 115342T=CCM 9308T).

Bioremediation of chlorophenol-contaminated sawmill soil using pilot-scale bioreactors under consecutive anaerobic-aerobic conditions.

Chlorophenols (CPs), including pentachlorophenol (PCP), are chemicals of concern due to their toxicity and persistence. Here we describe a successful reactor-based remediation of CP-contaminated soil and assess changes in the toxicity patterns and bacterial communities during the remediation. The remediation consisted of separating half of the contaminated soil to be ground (samples M) in order to test whether the grinding expedited the remediation, the other half was left unground (samples P). Both soils were mixed with wastewater treatment sludge to increase their bacterial diversity and facilitate the degradation of CPs, and the resultant mixtures were placed in 2 bioreactors, M and P, operated for 16 months under anaerobic conditions to favor dehalogenation and for an additional 16 months under aerobic conditions to achieve complete mineralization. Samples were taken every 4 months for toxicity and microbial analyses. The results showed a 64% removal of total CPs (ΣCPs) in reactor P after just 18 months of remediation, whereas similar depletion in reactor M occurred after ∼25 months, indicating that the grinding decelerated the remediation. By the end of the experiment, both reactors achieved 93.5-95% removal. The toxicity tests showed a decrease in toxicity as the remediation progressed. The succession of bacterial communities over time was significantly associated with pH, anaerobic/aerobic phase and the concentration of the majority of CP congeners. Our data indicate that the supplementation of contaminated soil with sludge and further incubation in pilot-scale bioreactors under consecutive anaerobic-aerobic conditions proved to be effective at the remediation of CP-contaminated soil.

The reproduction of Enchytraeus sp.--technical improvement for the counting of juveniles.

Soil-dwelling annelids of the genus Enchytraeus are used in ecotoxicology for testing of chemicals mixed in artificial soil or for testing of wastes and soils of unknown quality. ISO 16387 describes a method for determining the effects of substances or contaminated soils on survival and reproduction of Enchytraeus albidus or of the smaller species Enchytraeus buchholzi or Enchy-traeus crypticus. After the total test duration of 6 (or 4) weeks, the juveniles hatched in the meantime are counted. There are several possible extraction techniques, which are always followed by counting the juveniles by hand, but none of them seems easy to handle. We proposed a new modification of the worm extraction method using flotation of fixed and stained juveniles followed by taking a photograph. The digital image of the juveniles is evaluated by computer processing. It makes the counting of juveniles much easier and less labor intensive.