Modified implant surfaces show different biofilm compositions under in vivo conditions.

Objective: Plaque accumulation on implant surfaces can result in peri-implantitis with potential implant loss. The aim of the present study was to examine the influence of zirconium nitride (ZrN) as a potential implant surface on the biofilm composition and diversity in vivo.

Material And Methods: ZrN- or titanium (Ti)-coated glass specimens and ZrN or roughened Ti discs were used as substrates.

Microbial indicator groups in acidic mining lakes.

The salt composition of 14 acidic lakes was analysed, and their microbial communities were compared by their 16S rDNA-based single-strand conformation polymorphism (SSCP) fingerprints. The lakes were grouped into three chemically distinct types, and operational taxonomic units (OTUs) were identified in the 16S rDNA SSCP fingerprints. Discriminant analysis between these groups using a multivariate approach showed that not a single organism, but rather a set of seven OTUs (Ferromicrobium acidophilum, Bacillus pumilus, Acidophilium organovorum, Paenibacillus chibensis, Acidocella sp.

Diversity of biphenyl degraders in a chlorobenzene polluted aquifer.

Biphenyl degrading bacteria (40 strains) have been isolated along a gradient of chlorobenzene pollution from an aquifer which did not contain any PCB to answer the question of how metabolic/catabolic abilities exist in ecosystems that have not been stressed with the relevant substrates is important for intrinsic bioremediations. Only few of the isolates were characterized by 16S rRNA gene sequence analyses as Pseudomonas species while the majority were Gram-positive, belonging to the order Actinomycetales and representing the genera Rhodococcus and Arthrobacter. The strains could grow on a variety of chlorobenzoates but no pattern of substrate usage and phylogeny or pollution gradient could be found.

In vitro alterations of intestinal bacterial microbiota in fecal samples during storage.

The human gastrointestinal tract harbors an extremely diverse and complex microbial ecosystem. Most of the existent data about the enteric microflora have been generated using stool samples, but the collection and storage of fecal samples are often problematic. The influence of the storage of stool samples on the bacterial diversity and the degradation of bacterial DNA was analysed in this study.

Do different implant surfaces exposed in the oral cavity of humans show different biofilm compositions and activities?

Osseointegrated dental implants play an important role in restorative dentistry. However, plaque accumulation may cause inflammatory reactions around the implants, sometimes leading to implant failure. In this in vivo study the influence of two physical hard coatings on bacterial adhesion was examined in comparison with a pure titanium surface.

Chlorobenzene biodegradation under consecutive aerobic-anaerobic conditions.

The biodegradation of monochlorobenzene, the main contaminant in a quaternary aquifer at Bitterfeld, Central Germany, was studied in microcosm experiments employing either original groundwater or defined mineral media together with the indigenous microbial community from the polluted site. The impact of consecutive aerobic-anaerobic-aerobic incubations on monochlorobenzene biodegradation, microbial diversity, and pH development was examined. The related changes in microbial community composition were analyzed by 16S rRNA gene-based single-strand conformation polymorphism (SSCP) fingerprints and sequencing of dominant bands and by quantitative analysis of bacterial respiratory chain quinones as biomarkers.

Leitbakteria of microbial biofilm communities causing occlusion of biliary stents.

Biliary stents inserted to relieve obstructive jaundice caused by biliary or pancreatic malignancies inevitably become occluded by microbial growth in the form of diverse microbial community biofilms. The scarce information available on these communities is based on cultivation methods, but such methods usually provide distorted overviews of community composition, so commonalities and differences in biliary stent communities are uncertain. We extracted DNA and RNA from the microbial communities of 11 biliary stents explanted from nine patients in hospitals from two different countries, amplified 16S rRNA and rDNA sequences, analysed the amplicons by the single-strand conformation polymorphism (SSCP) method, and sequenced and deduced phylogenetic assignments of the major amplicons representing the major biofilm community members.

Simultaneous extraction from bacterioplankton of total RNA and DNA suitable for quantitative structure and function analyses.

The aim of this study was to develop a protocol for the simultaneous extraction from bacterioplankton of RNA and DNA suitable for quantitative molecular analysis. By using a combined mechanical and chemical extraction method, the highest RNA and DNA yield was obtained with sodium lauryl sarcosinate-phenol or DivoLab-phenol as the extraction mix. The efficiency of extraction of nucleic acids was comparatively high and varied only moderately in gram-negative bacterial isolates and bacterioplankton (RNA, 52 to 66%; DNA, 43 to 61%); significant amounts of nucleic acids were also obtained for a gram-positive bacterial isolate (RNA, 20 to 30%; DNA, 20 to 25%).