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MANUAL OF DETERMINATIVE BACTERIOLOGY 



Genus II. Microbacterium Orla- Jensen.* 



(The Lactic Acid Bacteria, 1919, 179.) From Greek mikros, small andM. L. bac- 

 terium, a small rod. 



Small rods. Non-motile. Gram-positive. Produce lactic acid but no gas from 

 carbohydrates. Surface growth on media is good. Produce catalase. Usually heat- 

 resistant. Found in dairy products and utensils, fecal matter and soil. 



The type species is Microbacterhim lacticum Orla-Jensen. 



Key to the species of genus Microbacterium. 



I. Acid from starch; survives 85°C for 21 minutes. 



1. Microbacterium. lacticum. 

 II. No acid from starch; survives 71.6°C for 2| minutes. 



2. Microbacterium flavum. 



1. Microbacteritim lacticum Orla-Jen- 

 sen. (The Lactic Acid Bacteria, 1919, 

 179; Corynebacterium lacticum Jensen, 

 Proc. Linnean Soc. of New So. Wales, 

 59, 1934, 50.) From Latin lac, milk; 

 M. L., pertaining to milk. 



Small tliin rods: 0.3 by 1.0 micron; 

 may have coccus-like appearance. Non- 

 motile. Granular. Gram-positive. 

 Angular and pallisade arrangements of 

 cells are characteristic. 



Agar slant : White or at times slight 

 greenish-yellow growth; adherent. 



Gelatin : No liquefaction. 



Milk: Acid, coagulation variable. 



Nitrites usually not produced from 

 nitrates. 



Indole not formed. 



Acid from glucose, fructose, mannose, 

 galactose, maltose, lactose, de.xtrin and 

 starch. No acid from xylose, arabinose, 

 rhamnose, or raffinose. Dextro lactic 

 acid formed. 



Catalase is produced. 



Temperature relations : Minimum 

 10°C. Optimum 30°C. Maximum 35°C. 

 Survives 85°C for 2§ minutes in skim- 

 milk. 



Aerobic to facultative anaerobic. 



Source : From cheese, milking equip- 

 ment, grass, human and bovine feces. 



Orla-Jensen {loc. cit., 180-181) identifies 

 the Bacillus acidophilus cultures ob- 

 tained by him from the Krdl collection 

 as belonging to this species. The charac- 

 ters of the Krdl cultures deviate from 

 the characters of Bacillus acidophilus as 

 given by Moro. 



Habitat : Human and bovine intestinal 

 tract and probably soil. 



2. Microbacterium flavxmi Orla-Jensen. 

 (Orla-Jensen, The Lactic Acid Bacteria, 

 1919, 181 ; Mycobacterium flavum Jensen, 

 Proc. Linnean Soc. of New So. Wales, 

 59, 1934, 34.) From Latin flavus, 

 yellov/. 



Rods : 0.5 by 1 to 2 microns. Granular 

 and therefore sometimes confused with 

 micrococci. Non-motile. Gram-positive. 



Agar: Surface growth usually yellow 

 and viscid. 



Gelatin: No liquefaction. 



Broth containing 10 per cent salt: 

 Grows as flaky precipitate. 



Milk: Slight acidity with no coagula- 

 tion . 



Nitrites produced from nitrates. 



Indole not formed. 



Acid from glucose, fructose, mannose, 

 galactose, raffinose and mannitol. No 

 acid from xylose, arabinose, rhamnose. 



* Arranged by Prof. C. S. Pederson, New York State Experiment Station, Geneva, 

 New York, June, 1938; further revision by Dr. M. L. Speck, Baltimore, Maryland, 

 Sept., 1943. 



