The Bacteria in the Neolithic Shellmounds

Abstract

Since VAN TIEGHEM found bacteria in fossils of plants in the year of 1879, many students found various bacteria of geological ages. The author also tried last year a bacteriological research of the Lower Pleistocene deposit of Nishiyagi beach in the suburbs of Akashi City. R. Katsunuma once found a sporforming Bacillus in Yoshiko shellmound with Jomonpottery. The author tried detailed bacteriological researches in various layers in three neolithic shelImounds with Jomonpottery in Kanto district, Okadaira in Ibaragi, Ubayama in Chiba Pref. and Kyu-Honmaru in the Imperial Palace in Tokyo. Some completely closed shells and mud were sampled from various layers by aseptic method, and aerobic bacteria were cultivated with normal agar medium (pH 7.0), anaerobic with glucose blood agar and both aerobic and anaerobic with thioglycolacidmedium. The species of bacteria were 52, and except for a few curious species the rest were identified to be common soil bacteria ; 14 Micrococcen, 1 Staplylococcus, 1 Gaffkya, 1 Aerobacter, 8 Achremobacters, 1 Flavobacterium, 24 Bacillen and 2 Clostridia. But the numbers of bacteria in shells are obscure except for two found in the Imperial Palace, that is the one 235 and the other 330. The more mud in completely closed shells increases in amount, the more numbers of bacteria increase. Anaerobic bacteria were all facultative. In shellmound bacteria live even in the depth of 370cm, and the species do not vary by the depth of the soil. However hard the shells are closed, some quantity of mud was found only in relatively shallower part. Ubayama shellmound is too shallow to research the bacteria in the shell, and Kyu-Honmaru had been partly put out of order. Even if new species were found in Ubayama and Kyu-Honmaru, we could not define them those of the neolithic age. Neither in the mud and shells of the scarcely mudded shell layer of Okadaira A Point, nor in the shells of the underlying mud containing shell layer, there could be found any bacteria. Those shells which contained no bactrtia did not contain much mud either. According to the stated fact, the author concluded that no sporforming bacteria of neolithic age could survive in Japan.