298 STATE BOARD OF ACJRICULTURE. 



(J ASSY (T'KI) AND CHEESE. 



liV ( . K. MAKSHAI-K. 



Bulletin 183. — Bacteriological Department. 



Already niiich has been written on this subject by Russell.' Bollcy and Hall,- Moore 

 and Ward;' Jcnsi-n.* Frciidciinielr' and Wfiumann." but specific cases must always 

 add to the interest of the matter and contribute to the fund of knowledge now at 

 hand. The conmiercial importance of the theme can be no greater elsewhere than in 

 Michigan, where the cheese is peculiarly adapted to gas formation on account of the 

 moisture, acidity and otlier striking qualities of the ^Michigan cheese. The loss accru- 

 ing from this trouble alone nuist be exceedingly great to the cheese-makers of Michi- 

 gan if we may judire from the number of reports coming to our notice in wliich gas is 

 held up as the principal agent of most failures. 



It is Tinderstood by all cheese-makers that the cause is traceable to micro-organisms 

 and that there is no specific individual species or specific gas which will acco>int for 

 every case. The micro-organisms producing gases are really more numerous as regards 

 species than the kinds of gases produced. Perhaps carbojiic acid gas and hydrogen are 

 the most common gases found, yet there is every indication that many more are 

 created, some of which have been detected chemically and others are known only by 

 their odoriferous characteristics. 



What causes one milk to result in gaseous curd or cheese and another to remain in a 

 satisfactory condition is readily attributable to tlie distribution of this class of bac- 

 teria which usually have their home in filth, such as is found about a cow stable. 

 Occasionally such a germ may find its way into the rnilk-duct, yet it is .seldom. Bolley^ 

 states that no gas-producing germ was found out of sixteen isolated from milk taken 

 from the udder under sterile conditions. Ward* finds very few bacteria in the interior 

 of the udder, which have any influence on the milk and further suggests that this 

 does not preclude the ])()ssil)le entrance of obnoxious bacteria. On the other hand 

 the author has frequently met with gas-producing or [erogenic bacteria in the study of 

 tilth in connection with "pure milk supply." It is also true that such micro-organisms 

 may be found commonly in milk, but fortunately for the cheese-maker they are con- 

 trolled by the ascendency of other micro-organisms which hold them in check. To 

 seek the origin of the trouble we must retuiii to tlie ever-present filth. What has been 

 said in regard to pure milk supply is eminently fitting to this case, and the cheese- 

 maker will profit through the persistent care of the milk producer. 



It was during the short dairy course of 1898 that a marked inflation of the curd in 

 the vat was noticed. I undertook to isolate the off"ending cause. This was accom- 

 plished, after a series of inoculations in milk-tubes had been made, then, plating in 

 ordinary gelatin, neutral in reaction to litmus. The suspected germ gave rise to 

 numerous colonies, which could be easily isolated from the other colonies present 

 because of the rapidity of their development. Repeated plating was resorted to, that 

 purity of isolation might be satisfactorily established. The germ thus obtained was 

 capable of producing an abundance of gas in milk during a very short period if placed 

 in a suitable temperature. 



TUK IIKSTOKY OF TJIK IJACIL.MS WHICH SIMULATES TIIK BACILLUS COLI COMMU.MS. 



1 wish to consider in recording the actions of this bacillus, its relation to the 

 bacillus coli communis and also to the micro-organism isolated by Moore and Ward 

 in this same connection. In order to verify the influence of this bacillus upon the 

 making of cheese, a starter was made to take the place of the ordinary lactic acid 

 starter used in bringing the milk up to its proper acidity. It was found that 



