Thermophilic bacteria

THE range of temperature a t which it is possible for bacteria to grow is very great.Forster) for example, proved that certain bacteria were capable of growth and multiplication a t zero.These organisms were found by him in water, milk, soil, and street mud.When cultivated a t this low temperature they still produced pigment, gas, light, etc.The apparently unfavourable external conditions did not overcome the vitality of the cells or interfere with the exercise of their specific properties.For a large number of bacteria, 15"-20" C. is the optimum temperature, whilst for pathogenic bacteria the optimum temperature is blood heat.A t temperatures above 40" C. relatively few micro-organisms grow, and a t 50" C. most nonspore-bearing organisms quickly die.But there is undoubtedly a group of micro-organisms which can grow a t temperatures above 50" C., and for which such high temperatures furnish the best conditions for their growth and development.Miquel's Bncillw thrntophilzts2 is perhaps the most familiar example.It was found by him in air, rain water, river water, and in the alimentary canal of man and animals.Van Tiegheni a also describes a inimococcus which grew at 70" C., and Certes and Garrigon4 found, in the waters of Luchon, bacilli that could be cultivated a t 64" C. The temperatures at which it is possible for bacteria to grow range therefore from zero to 70" C. Globig: on inoculating sterile milk and beef-broth with garden earth, obtained a growth of bacteria at 58" C.They were exclusively bacilli, and in many cases they produced spores after 24 hours' incubation a t this temperature, potatoes being used as a culture soil.Globig obtained 30 bacteria, which grew at 58" C.One bacillus grew at 68" C. and also a t 15"-20" C.This was the greatest range of It grows best at a temperature of from 65"-70" C.A t 68" C. only a few continued to grow.