Occurrence in artificial and natural environments

The beer-spoilage species Megasphaera, Pectinatus, Propionispira and Selenomonas have been isolated from the beer production process and/or spoiled beers, and with a few exceptions their habitats in natural environment are unknown. 

The beer-spoilage P. cerevisiiphilus, P. frisingensis, and P. haikarae species have mainly been isolated from spoiled unpasteurized and flash-pasteurized beers 

Culture-independent analysis of microbial diversity in industrial and natural ecosystems has revealed new habitats for S. lacticifex. DNA sequences from S. lacticifex have been detected from a biomass of a continuous stirred tank reactor, sewage from a wastewater treatment plant and from the food waste hydrolysate (http //www.ncbi.nlm.nih.gov/genbank/). The close evolutionary relation of the beer-spoilage P. raffinosivorans to a tree pathogen P. arboris suggests that it may be carried to breweries with plant raw materials (Juvonen, 2009). 

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We discussed the sources of artificial occurrence of " Tc at the beginning of this chapter and demonstrated that the nuclear fuel cycle is the predominant source of Tc in the environment. Other, much less important, sources are the fallout from nuclear weapons testing, the Chernobyl accident, nuclear power production and the radiopharmaceutical use of the metastablc "Tc decaying to ground state Tc. The natural occurrence of Tc formed in the earth s crust by spontaneous fission of and neutron-induced fission of in uranium ores are negligible. 

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