CAROTENOIDS IN PLANTS 



zeaxanthin, and cryptoxanthin ; ' s, 9 5 ]\/[ lacticola ^ ® produces an acidic 

 carotenoid (probably astaxanthin) or a neutral xanthyphyllic pigment 

 according to the constituents of the culture medium. Recently a war- 

 time Japanese report has become available which indicates that the 

 soyama B strain of M. tuberculosis grown on Santon's synthetic medium 

 contains either (3-carotene of leprotene, probably the latter." 

 Lederer*'^ has recently found leprotene in Mycohact. bruynoghe and 

 adant. 



Thiobacteriales 



Rhodobacteriaceae. The first modem investigation of the carotenoids 

 of the sulphur-containing bacteria was carried out by Levy, Teissier 

 and Wurmser^^ in 1925; they obtained from Chromatium okenii z 

 carotenoid identical with oL-bacteriopurpurin. It occurred in the bacter- 

 ium as a brown chromoprotein soluble in dilute NaCl solution. These 

 workers also showed that the bacterioerythrin of Archichovsky ® ^ is in 

 all probability a-bacteriopurpurin. Karrer and his colleagues ^ <'*'- ^ "^ ^ 

 investigated Rhodovibrio^ Rhodobacillus and Thiocystis and described 

 five new pigments : flavorhodene, rhodopurpurene, rhodoviolascin, 

 rhodopitiy and rhodovibrin ; ^-carotene is the only common carotenoid 

 present in these organisms and even so it is only a very minor con- 

 stituent. 



Rhodoviolascin (C42Heo02) probably has the following structure : 



Me Me Me Me—" v 



\ r— Me Me Me Me 



Rhodoviolascin 



Rhodopin (C40H58O) is a monohydroxycarotenoid of undetermined 

 structure. Rhodovibrin contains two oxygen atoms, but only one 

 hydroxyl group, and is methoxyl free. Rhodopurpurene (C40H58 or ss) 

 and flavorhodene are hydrocarbons of indefinite structure, the former 

 may be identical with lycopene and the latter with either e-carotene or 

 neurosporene, more probably owing to its adsorption properties, with 

 the former, {see p. 28) Fig. 20 gives the absorption spectra of some of 

 these pigments. 



Athiobacteriales 



Van Niel and Smith ^"' isolated a carotenoid which they called 

 spirilloxanthin from Rhodospirillum rubrum. More extended investiga- 

 tions of this pigment have led Polgar, van Niel and Zechmeister ^ ° * 



121 



