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A research focused to find whether the crops treated with antimicrobials are likely to expose the users to antimicrobial-resistant bacteria from the environment is conducted in the culturable microbiota of lettuce gathered at one organic and nine other traditional farms in Costa Rica to detect the presence of oxytetracycline- and gentamicin-resistant bacteria. It was observed that both the varieties of resistant species formed an important part of all culturable bacteria and included various resistance genes and factors for their likely horizontal transfer.

The microbial composition of biofilms from a beer bottling plant was analyzed by cultivation independent analysis of the 16S rRNA genes. The clone libraries were differentiated by amplified 16S rRNA gene restriction analysis and representative clones from each group were sequenced and diversity of the clone libraries was comparable with the diversity found for environmental samples.

Samples from diverse upland soil that oxidase atmospheric methane was characterized with regard to methane oxidation activity and the community composition of methanotrophic bacteria (MB). The data indicate that different MBs are present and active in different soils that oxidize atmospheric methane.

A method for the detection of physiologically active autotrophic bacteria in complex microbial communities was developed based on labelling with the stable isotope 13C. Labelling of autotrophic nitrifying, sulphur-oxidizing and iron-oxidizing populations was performed in situ by incubation with NaH[13C]O3. Incorporated label into fatty acid methyl esters (FAMEs) was detected and quantified using gas chromatography-mass spectrometry in single ion monitoring mode. Before the analyses of different environmental samples, the protocol was evaluated in pure culture experiments. In different environmental samples a selective labelling of fatty acids demonstrated which microbial taxa were responsible for the respective chemolithoautotrophic activity. The most strongly labelled fatty acids of a sample from a sulphide treating biofilter from an animal rendering plant were cis-7-hexadecenoic acid (16:1 cis7) and 11-methyl hexadecanoic acid (16:0 11methyl), which are as-yet not known for any sulphide-oxidizing autotroph. The fatty acid labelling pattern of an experimental biotrickling filter sample supplied with dimethyl disulphide clearly indicated the presence and activity of sulphide-oxidizing bacteria of the genus Thiobacillus. For a third environmental sample from an acid mining lake sediment, the assignment of autotrophic activity to bacteria of the genus Leptospirillum but not to Acidithiobacillus could be made by this method, as the fatty acid patterns of these bacteria show clear differences. [ABSTRACT FROM AUTHOR]

Describes the characterization of styrene-degrading microbial populations of biofilters used for treatment of waste gases. Use of deuterated styrene as a tracer in combination wtih phospholipid fatty acid analysis; Characteristics of deuterated fatty acids; Effects of deuterated compounds on enzyme activities.