Effect of the presence of the antimicrobial tylosin in swine waste on anaerobic treatment.

An anaerobic sequencing batch reactor (ASBR), seeded with a biomass inoculum that previously had not been exposed to the macrolide antimicrobial tylosin (mixture of Tylosin A, B, C, and D), was operated for 3 months with swine waste without Tylosin A and for 9 months with swine waste containing Tylosin A at an average concentration of 1.6 mg/L. When swine waste with tylosin was fed to the ASBR, methane production and volatile solids removal did not appear to be inhibited and a methane yield of 0.

Biodegradation of chlorobenzene under hypoxic and mixed hypoxic-denitrifying conditions.

Pseudomonas veronii strain UFZ B549, Acidovorax facilis strain UFZ B530, and a community of indigenous groundwater bacteria, adapted to oxygen limitation, were cultivated on chlorobenzene and its metabolites 2-chloro-cis,cis-muconate and acetate/succinate under hypoxic and denitrifying conditions. Highly sensitive approaches were used to maintain defined low oxygen partial pressures in an oxygen-re-supplying headspace. With low amounts of oxygen available all cultures converted chlorobenzene, though the pure strains accumulated 3-chlorocatechol and 2-chloro-cis,cis-muconate as intermediates.

Bacterial diversity in the active stage of a bioremediation system for mineral oil hydrocarbon-contaminated soils.

Soils contaminated with mineral oil hydrocarbons are often cleaned in off-site bioremediation systems. In order to find out which bacteria are active during the degradation phase in such systems, the diversity of the active microflora in a degrading soil remediation system was investigated by small-subunit (SSU) rRNA analysis. Two sequential RNA extracts from one soil sample were generated by a procedure incorporating bead beating.

Alternative primer sets for PCR detection of genotypes involved in bacterial aerobic BTEX degradation: distribution of the genes in BTEX degrading isolates and in subsurface soils of a BTEX contaminated industrial site.

Eight new primer sets were designed for PCR detection of (i) mono-oxygenase and dioxygenase gene sequences involved in initial attack of bacterial aerobic BTEX degradation and of (ii) catechol 2,3-dioxygenase gene sequences responsible for meta-cleavage of the aromatic ring. The new primer sets allowed detection of the corresponding genotypes in soil with a detection limit of 10(3)-10(4) or 10(5)-10(6) gene copies g(-1) soil, assuming one copy of the gene per cell. The primer sets were used in PCR to assess the distribution of the catabolic genes in BTEX degrading bacterial strains and DNA extracts isolated from soils sampled from different locations and depths (vadose, capillary fringe and saturated zone) within a BTEX contaminated site.

Two unusual chlorocatechol catabolic gene clusters in Sphingomonas sp. TFD44.

The genes responsible for the degradation of 2,4-dichlorophenoxyacetate (2,4-D) by alpha-Proteobacteria have previously been difficult to detect by using gene probes or polymerase chain reaction (PCR) primers. PCR products of the chlorocatechol 1,2-dioxygenase gene, tfdC, now allowed cloning of two chlorocatechol gene clusters from the Sphingomonas sp. strain TFD44.