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Abstract In this i,•estigatirr li ty single cell p:::.”otein ( :. ) . Those cultures w;::re thus, screened according tcJ tLeir yield 9 yield coefficient, protein, total carbohydr&tes, ,;lucan, mannan and amino acids content. Propagation of these cultures 1NHS carried on moL:.sses mediwn as a sui table cheap rsvv material for ycc’ast propagation. It was fo1F~d that t!!ece straL1s vary consider·- ably in their rate of gro~th and different parameters ,~,f the ~uality of their :;cp. It was also fou~d tnat strains belonGing to S.cerevisiae were the j’Yjost active The i ’lVe stigated cul htres werr; also fonnd ”to show consider.J,ble ;:ifferences in cru’~f’ prDtein conte. nt, \Jitn r;b: highest levels .Ll: ’.:me ~:Otrrin~ ur cerevisiae. in iif:’ r’-~nt cultures. .E. e()tl..-cystine figures. Acco rdinc:: to the s.bo ve study three cultures, which showed, the highest yield, lo·,vest glucan and mannan, and the highest metl:ionine, cystine and lysine were selected for further studies. The selected cul- 562) and C .yui.J.::j.s (CBS 397), These cultures were exposed to N-nitronitrosoquanidine as a potent chemic2l mutagen, and the produced t=1.~J.xctrophic mutR.:-::tE; were picked. This study sho~ed that the number f survivals decreased as the time nf expos1.cre to the mutagen increased. The percentage of auxctrophi:: mutants to the total survivals increased with 1ncrease of the expo sure to the chemical rn’;t ,<’ro::n t!J’ YHJ. tag en ic tre8.tmi:>nt a larfc~C c :J lle ctiu, f aux- tra ph:L,:; : :u tR.r+:;:; v;ere picked. These includr:· ~·~ mut 11ts L·cJr:; ~.,cerevisiae ~.ts from c.utilis ,· ~- c~ ~ ... .:_~) ”-:.’ r) \ L · ~on with thei:•” pan: t cult; The select::d tr,rcl’ btc’St ’lluta .Js and ibt:ir par-- ents were used to .study the effect of enviromnental factors on their yield and different criteria of the quality of their SC?. It was found from this study that the sugar concentration in the propagation medium hds a clear effect on the yield and quality of the pi!!oduct. The highest yield for the three mut’ nt and their original cultures was at Ji) sug:::cr concc’ tration. T{le total c~:trbohydrates, T<annar:c and glucan content was incre&sed by increhsing t’ ~ sugar rJncentration for all tho tested str~ins. clear difference between p~rental cultures and their u_ tant s were Lower than par<” nt~-”1 cul tt;res in Pli_L’1nan and ,c;::lucan Cclltent-~ that -.. J_l ,!Ulst s i_ .r·.=ti:ts t__lti_lizcd rrnJ.tar.. . ts. gen source f()r C.albicans and its m~~ants. Nitrogen source had no effect on total carb8- hydra tc, mannan a.::1d glucan in the mutants and their original culture:=:;. pli value of the e;:co·/:th me diu:\ was ,:tlsn found to affect the gro th of the studied yeast cultures. mutants was at p, - 3.5. ~Vl1i~e for c.albicans and its ’,, ---- - -~-~”” mutants was at pi’l 5.5. t1ll carbohydrate, :;lannan and glucan follo d tho f:.;<c,me trend. Thei:r level generally increased ~ith th~ increase in pH. The lowest total c:trbohy rate, TLLannnn and glucan \V’’lS at pH J. 5. f’Jr all the three .strairw e”nd t:1eir muta~-cts. VIhilc .utilis ·u1•’i i+;s muti:mt. ’L’hc grov. t el i’c c+; r: -,tal ERn ancl glucan i1 slowed by ’:c: mut nt by the lowest man~~n and Glucan cnnte, t. |