rHoDicrioN OF i;\z>Mi:s 



191 



l*(Mii<-illiiias(> 



'riu> ;il)ilit\" of ;ict iiioinycclcs to jji-odiicc 

 IX'iiicilliiinsc, tlic cnzyinc capahlc of o.\iiliziii<i; 

 IHMiicilliii, is \vi(l{>ly (list i'il)ut(Hl. St rcptoiny- 

 ('(Mcs arc in i^ciu'ra! I'csislaiit to penicillin; 

 thci'c is no relation, howcN'ef, between peni- 

 cillin-fesistance ami t'oiMuation of penicilli- 

 nase. This enzyine is heat -labile. It can be 

 concentrated by j)i'ecipitat ion with aninio- 

 niuni sulfate and acetoiu^, a ivspon.se that 

 suii'jfests its protein nature (Welsch). 



Tyrosinase 



Tlie protluclion of a brown j)iji;nient by 

 actinomvcetes grown on protein media has 

 usually been associated with the ability of 

 the organisms to form tyrosinase. According 

 to Beijerinck, there is involved in the reac- 

 tion the formation of a ([uinone, which turns 

 brown at an alkaline reaction and in the 

 presence of oxygen. The action of ciuinone 

 in the presence of iron was found to be simi- 

 lar to that of the enzyme tyrosinase. Since 

 an excess of oxygen is required for the for- 

 mation of the ciuinone, only limited amounts 

 are found in deep cultures. The quinone is 

 belie^■ed to be formed from the peptone in 

 the medium; although good growth was pro- 

 duced on media containing asparagine, 

 KXO.'i , and ammonium sulfate as sources 

 of nitrogen, only traces of quinone, if any, 

 were found. The tyrosinase reaction is not 

 involved in the production of all black pig- 

 ments by actinomycetes; some species pro- 

 duce such pigments in purely synthetic 

 media in the complete absence of peptone. 



It has always l)een assumed that the po- 

 tato scab organism is a chromogene, and that 

 the formation of the black pigment is due to 

 the tyrosinase reaction. Millard and Burr 

 reported, however, that some of the plant 

 pathogens did not give the tyrosinase reac- 

 tion. Afanassiev could not confirm the patho- 

 genicity of these cultures. Skinner concluded 

 that the production of a dark color by the 



chronioiienic ad inoniycetes is due to tyro- 

 sine metabolism. 



(Jregoiy and Vaisey found that natural 

 and .x-i'ay-induced mutants of .S. saihies were 

 tyiosinase-delicienl and did not produce a 

 brown ring in skim milk. All tyrosinase- 

 l)ositi\-e cultures i)r()(luced the brown ring. 

 The tyi'()sinas(>-delicient cultures were \'iru- 

 leiit for potatoes. This fact demonstrates 

 that there is no coiniection Ix'tween patho- 

 genicity and the tyrosinase reaction. 



Steroid Oxidation 



The ability of \-arious actinomycetes to 

 oxidize steroid hormones has recently at- 

 tracted considerable attention, as shown in 

 Chapter 9. "Resting cells" of certain strepto- 

 mycetes are able to transform steroids. Ac- 

 cording to Turfitt (1944), various species of 

 Nocardia are capable of attacking steroids, 

 with the possible exception of halogen-sub- 

 stituted derivatives. The oxidation of cho- 

 lesterol results in the formation of a choles- 

 terone, followed by molecular fission, the 

 products of which may be utilized by the 

 organisms for their further growth. 



Perlman et al. (1957) studied the enzymes 



Table 47 



Aryl sulfatase activity of rapidly yruwing iiiyco- 



bacteria, nocardias, streptomyces and corynebac- 



teria (Wayne, Juarez, and Nichols) 



