Mi()('iii;.Mic.\i. Acnx i'rii;s 



155 



l>e<'Uiii|>osi(i(tii of (lliitiiis 



C'liitin-diM'oiuposiiii;- ;i('lin<)niv('('t(\s arc 

 widely (list rihutcd in nature. As many iis <S") 

 per cent of t lu> N. (ilhnjlartis f^roup, 84 per 

 cent of the »S'. alhia^, K] per cent of tlie S. 

 rubrirch'culi, 82 per cent of the N. (/risciis, 

 75 per cent of N. scabies, and only n few (oil 

 p(M' cent) of the N. riolncciis j;-roups possess 

 this cai)acity. Only a hnv types of chitin- 

 d(>coniposinii; actinoniycetes ha\'e heeii louiid 

 in for(\st soils. This may he due i)ossil)ly to 

 the lack of small arthi'opoda in such soils. 



The act inoniycetes attackin.i;' chitins do so 

 by means of certain en/cym(\s, designated as 

 chitinas(\ Berger and K(\vnol(ls studied these 

 enzyme systems found in the culture filtrates 

 of a streptomyces capable of hydrolyzing 

 ciiitin. Th(> following compounds were 

 formed dining the digestion process: ^V- 

 acetylglucosamine, a /i-l ,4-linked disaccha- 

 ride, X .X'-diacetylchitobiose. At least two 

 enzymes were found iu the mixture: 1, a 

 h(\it-labile fraction was able to split the 

 disaccharide to glucosamine, but was unalile 

 to hydrolyze the chitin; 2, a heat-stal)le 

 fraction contained a chitinase which hydro- 

 lyzed the chitin to e(iuimolar concentrations 

 of the two fractions, l)ut did not clea\-e the 

 disaccharide; the system is specific for poly- 

 mers of X-acetjdglucosamine. The chitobiase 

 hydrolyzed the i3-phenyl glucoside of X'-ace- 

 tylglucosamine but not the glucosides of 

 glucosamine or glucose. Further information 

 on chitinase is given in Chapter 1 1 . 



Decomposition of Cellulose 



As pointed out previously, various actino- 

 mycetes inhabiting soils, high-temperature 

 composts, and sewage sludge are capable of 

 attacking cellulo.se. Krainsky, Waksman, 

 and BrussofT were among the first to demon- 

 strate the capacity of various actinomycetes 

 to carry out this process. Unfortunately, 

 little is known of the enzj^matic systems in- 

 volved in the action of these organisms upon 



ceilulo.se. The onl>- products obtained are 

 usually slim\- materials and pigments that 

 I'ange from red and yellow to blue and black, 

 {''urtlicr inlornialion on ccllulase is gi\'en in 

 Chapter I I. 



Ill a study of cellulose decomposition by 

 termites, Ilungale isolated a culture of a 

 micromonospora that decomposed cellulose 

 under anaerobic conditions. The presence of 

 complex organic substances in the medium 

 is reciuircd. .Vmong the products formed, 

 acetic and propionic acids were identified, 

 in addition to C()-j . An old culture of mici'o- 

 monospora contained cellulase tiiat con- 

 verted the cellulose to glucose. Hungate 

 isolated another strain of the anaerobic 

 micromonospora fi-om a culture of protozoa 

 from the rumen of cattle. The organism is 

 referred to as .1/. propionici. 



Decomposition of Starches and Hemi- 

 celluloses 



Starches arc also decomposed by numerous 

 actinomycetes. The problem of isolating di- 

 a static enzymes is much simpler, since it is 

 very easy to study this process and isolate 

 final products. 



Hemicelluloses and polyuronides, includ- 

 ing mannans, galactans, glucans, xylans, as 

 well as pectins, agar (Stanier), and others, 

 are decomposed by a large number of actino- 

 mycetes. Some of these actinomycetes are 

 more active than fungi. 



Further information on amylase and cy- 

 tase is given in Chapter 11. 



Decomposition of Rubber 



Sohngen and Fol (1U14) reported that 

 actinomycetes are capable of attacking rub- 

 ber, bringing about a reduction in viscosity 

 and transfoi'mation into CO2 . Several spe- 

 cies, notablv .1. J'uscus and A. elastica, were 

 isolated. They were found capable of utiliz- 

 ing various salts of organic acids, including 

 stearate and palmitate, but not formate. 



