Abstract
A study was made to determine if samples of building materials derived from the urban environment contain bacteria (including ultrasmall forms), in relation to the possibility that man-made (or formed) materials from the urban environment contain microorganisms. This was done in relation to the possibility that if the building materials are ejected from Earth during an impact event the microorganisms which they could carry with them might be capable of colonising other planets. This theory we refer to here as "archipanspermia" ("archi"-as in architecture). A technique for isolating bacteria from rocks was used which excludes the possibility that any of the isolates from the building materials resulted from contamination. Species of Bacillus were found in all of the samples tested (i.e. bitumen, brick, cement, mortar sandstone and slate), although no ultrasmall (0.2 mu m filterable bacteria) were isolated from any of the samples. It is concluded that species of the spore-forming genus Bacillus could therefore be potentially ejected from Earth in these materials obtained from the man-made environment; in this way evidence is provided in support of our theory of archipanspermia.