A laminar air flow cabinet is an essential tool in microbiology – including paleomicrobiology, a relatively new field that aims to identify and characterise the microorganisms responsible for infectious diseases in the past. Because of the risk of sample contamination biosafety cabinets are typically used, which also offer protection to the user if the pathogens are then cultured.
Until recently, the data supporting pathogenic microorganisms at archaeological sites has been scant. However, a new total sequence screening technique has enabled accurate molecular identification of ancient bacteria for the first time.
PCR and the laminar flow hood
Genomic technology is routinely used to identify and isolate microbial DNA. However, it is difficult to extract ancient DNA from archaeological samples owing to the quality and quantity present, and environmental contamination by present-day bacteria. Using a laminar airflow cabinet prevents contamination of the sample, but DNA analysis will not be able to chronologically differentiate between bacteria. However carefully samples are gathered, any DNA present will originate from a variety of sources, both pre and post-burial, making the identification of causative pathogens extremely difficult.
In 2011, this problem was tackled by Catherine Treves et al, who identified bacterial pathogens in five bodies buried in the Siberian permafrost during the 17th to 19th centuries. Using the relatively new PCR (polymerase chain reaction) technique, individual DNA sequences were identified, amplified and cloned, using biological safety cabinets inside clean rooms adapted for ancient DNA analysis.
The experiments gave valuable data concerning the evolution of infectious organisms, and a fascinating new use for the laminar flow hood.
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