Contamination by chloroethenes has a severe negative effect on both the environment and human health. This has prompted intensive remediation activity in recent years, along with research into the efficacy of natural microbial communities for degrading toxic chloroethenes into less harmful compounds. Microbial degradation of chloroethenes can take place either through anaerobic organohalide respiration, where chloroethenes serve as electron acceptors; anaerobic and aerobic metabolic degradation, where chloroethenes are used as electron donors; or anaerobic and aerobic co-metabolic degradation, with chloroethene degradation occurring as a by-product during microbial metabolism of other growth substrates, without energy or carbon benefit. Recent research has focused on optimising these natural processes to serve as effective bioremediation technologies, with particular emphasis on (a) the diversity and role of bacterial groups involved in dechlorination microbial processes, and (b) detection of bacterial enzymes and genes connected with dehalogenation activity. In this review, we summarise the different mechanisms of chloroethene bacterial degradation suitable for bioremediation and provide a list of dechlorinating bacteria. We also provide an up-to-date summary of primers available for detecting functional genes in anaerobic and aerobic bacteria degrading chloroethenes metabolically or co-metabolically.

A novel enzyme-labelled-fluorescence (ELF) method was applied to natural populations of planktonic rotifers from a eutrophic reservoir. Direct visualisation of rotifers by this new method provided new information about enzymatic activities in situ, including detection and location of enzyme activities. Three fluorogenic substrates were used for the enzyme assay in concentrated (20–60×) samples of the rotifers. After a short (1–3 h) incubation in test tubes, samples were filtered and the rotifers on polycarbonate filters were examined using an epifluorescence microscope. Activity of phosphatases, β-N-acetylhexosaminidases and lipases were detected in some species that were regularly inspected during two seasons – most frequently in the stomach area, at the corona and, less often, in the mastax area. The results suggest that most of the detected enzymes are connected with the digestive tracts of rotifers. Also, autofluorescence of chlorophyll a enabled visualisation of the digestive tracts of the rotifers and provided additional information on the food (phytoplankton). Enzyme expression did not show any clear seasonal trend. Detection of specific enzymes varied considerably between species of rotifers and between individuals. This variability could be a result of change of feeding behaviour of rotifers in the concentrated samples and also could reflect individual differences among the rotifers in a population, such as feeding activity, age or life stage.

Despite it is widely acknowledged that the ability to hydrolyze dissolved organic matter using extracellular phosphatases is diverse in freshwater phytoplankton, the competition within single species related to presence and quantity of cell-

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