Another interesting application of micro-organisms to the purposes of the distilling industry has been worked out by Boidin and Effront.

In the saccharification of starch by means of malt, the malt is an expensive ingredient, and much of it is used up in liquefying the starch. In both the malt conversion and the amylo-process there is a considerable loss of the nitrogenous constituents of the grain, over and above what is necessary for nutrition of the yeast, by reason of the conversion of proteins into soluble nitrogenous compounds which pass away in the residual liquid after the alcohol has been distilled off.

Boidin and Effront seek to avoid or minimise this loss, to economise malt, and also to obviate the need for "cooking" or steaming tin-grain under pressure in the preliminary stages of mashing. This they do by the use of bacterial enzymes capable of liquefying starch but having little or no action on the proteins.1 The organism employed is a certain species of Bacillus mesentericus, "acclimatised" by cultivation under the special conditions to produce a maximum amount of enzyme. The bacillus is grown in an alkaline medium, strongly aerated; the culture liquid thus obtained has an activity such that it will liquefy 1000 times its weight of grain, and by concentration in vacuo products six times as strong can be prepared. In using these enzymes, the grain is first soaked in an alkaline solution, then coarsely ground, mixed with two volumes of water, and heated to 75-80°. The solution of the enzymes is added at this temperature, and allowed to act for a period of thirty to sixty minutes, by the end of which time the starch is all liquefied. Then the mash is heated for some time at 110-120°, and subsequently cooled to 60° in open vats. Malt is now added, in the proportion of 1 to 2 per cent. of the grain, and the saccharifying action allowed to proceed for an hour. By reason of the previous liquefaction, this small amount of malt suffices for complete saccharification, and it also supplies sufficient yeast nutriment.

After cooling, the wort is " pitched " with yeast acclimatised to hydrofluoric acid, and the fermentation completed as usual.

In this way a larger amount of nitrogenous substance remains

1 Effront, "Biochemical Catalysts in Life and Industry," p. 615. (Wiley, 1917.) undissolved in the "grains" or residue from the mash, and is available as a foodstuff for cattle, instead of being rendered soluble and run to waste in the spent lees, as in the ordinary process.