Study of the response of a biofilm bacterial community to UV radiation

Article Abstract:

A bioluminescent whole-cell biosensor that responds to DNA damage and can be incorporated into biofilm ecosystems has been developed to study the response of a Pseudomonas aeruginosa biofilm to stress. A P aeruginosa derivative carrying a plasmid-based recA-luxCDABE fusion, RM4440, was immobilized in an alginate matrix to simulate a biofilm and its response to UV radiation damage investigated. It has been observed that the alginate biofilm transmits only a small amount of UV radiation, thus shielding the cells from exposure and indicating that the exopolymer may be a natural defense mechanism for attenuating UV light exposure in nature. RM4440 has been proven to be a useful tool for the noninvasive study of microbial communities.

Design and construction, Ultraviolet radiation, Biosensors, Microbial populations

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Estimation of bacterial cell numbers in humic acid-rich salt marsh sediments with probes directed to 16S ribosomal DNA

Article Abstract:

A quantitative method of microbial community structure analysis is introduced and applied to an analysis of the structure o a bacterial community in humic acid-rich salt marsh sediments. The technique eliminates polymerase chain reaction, culturing and enrichment steps, reduces some of the sources of bias inherent in soil nucleic acid extractions and gives reproducible results with sediment samples at a threshold of detection of ca 8 x 10(super 5) cells gram of sediment(super -1).

Bacteria

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Genetic diversity among Arthrobacter species collected across a heterogeneous series of terrestrial deep-subsurface sediments as determined on the basis of 16S rRNA and recA gene sequences

Article Abstract:

The permeability of deep sediments determines the mix of bacteria that are present. In impermeable sediments, the bacteria are mostly monophyletic. Higher-permeability gravel has a more diverse ecology.

Microbial ecology

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