56 CLASSIFICATION OF BACTERIA 



Tribe l.Chromobactercp. Water bacteria producing a red or 

 violet pigment. 



Genus l. Erythrobacilhis. Small aerobic bacteria, producing a 

 red or pink pigment, usually a lipochrome. Gram stain variable. 

 It is possible that related yellow and orange chromogens should be 

 included here as well. Type species, E. prodigiosus (Ehrenberg). 



Genus 2. Chromobacterium. Aerobic bacteria, producing a violet 

 chromoparous pigment, soluble in alcohol but not in chloroform. 

 Motility and Gram reaction variable. Type species, Chr. mokecum 

 Bergonzini. 



Tribe 2. Erwinece. Plant pathogens. Growth usually whitish, 

 often slimy. Indol generally not produced. Acid usually formed in 

 certain carbohydrate media, but as a rule no gas. 



Genus 3. Erwinia. Characters those of the tribe. Type species, 

 E. amylowra. 



Tribe 3. Zopfece. Gram-positive rods, growing freely on arti- 

 ficial media. Not attacking carbohydrates. 



Genus 4. Zopfius. Long rods occurring in evenly curved chains. 

 Gram-positive. Motile. Proteus-like growth on media. Faculta- 

 tive anaerobes. Carbohydrates and gelatin not attacked, hydrogen 

 sulphid not formed. Type species, Z. zopfi (Kurth) Wenner and 

 Rettger. 



Tribe 4. Bacterece. Gram-negative rods growing freely on 

 artificial media. Generally forming acid from carbohydrates and 

 often gas composed of CO 2 and H 2 . 



Genus 5. Proteus. Highly pleomorphic rods, filaments and 

 curved cells being common as involution forms. Gram-negative. 

 Actively motile. Characteristic ameboid colonies on moist media. 

 Liquefy gelatin rapidly and produce vigorous decomposition of 

 proteins. Ferment glucose and sucrose (but usually not lactose) 

 with formation of acid and gas (the latter being C0 2 only). Type 

 species, P. vulgaris Hauser. 



Genus 6. Bacterium. Gram-negative, evenly staining rods. 

 Often motile, with peritrichic flagella. Easily cultivable, forming 

 grape-vine leaf or convex whitish surface colonies. Liquefy gelatin 

 rarely. All forms except B. alcaligenes and the B. abortus group 

 attack the hexoses and most species ferment a large series of carbo- 

 hydrates. Acid formed by all, gas (CO 2 and H 2 ) only by one series. 

 Typically intestinal parasites of man and the higher animals although 

 several species may occur on plants, and one (B. aerogenes) is widely 

 distributed in nature. Many species pathogenic. Type species, 

 B. coli Escherich. 



Tribe 5.Lactobacillece.l\ods often long and slender, Gram- 

 positive, non-motile, without endospores. Usually produce acid 

 from carbohydrates, as a rule lactic. When gas is formed it is CO 2 



