8/13/2019 Pengaruh Fosfat Pada Perkembangan Ashbyii

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8/13/2019 Pengaruh Fosfat Pada Perkembangan Ashbyii

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132 H B Mehta and V V Modi: Flavinogenes is in remo thecium a~hbyiiAs shown in Fig. i, maximu m flavin produc-

tion occurred at a concentr ation (io5.10-3~4)of phospha te which is suboptimal for growth.Increasing the phosphate concentration in themedium f rom O.O015 ~4 to 150 mM increased thegrowth by 70% but decrease d the accumula tion offlavins in the broth by 60%. However, at thesame time the value of total flavin expressedin terms of growth (specific flavins) was de-creased by 80%. This probably ind icated redu cedflavinogeni c efficie ncy of cells grown in thehigh phosphate (150 mM). It was interest ing tonote that under the same condition, the ratioof riboflavin to F~Z was lowered nearly seventimes. This was beca use the amo unt of F 89 in-creased by two fold whereas that of riboflavin,express ed in terms of mg. dry wt., was de creasedby 78%.The inhibition of riboflavin production couldbe correlated with the phosphate inhibition ofGTP cyclohydrolase which catalyzes the firststep in riboflavin biosy nthesis (Mehta and

Modi, submi tted for publication). It seems,therefore that in cells grown in high phosph ateconcentrations, F~q formation is favoured and/or a part o f the riboflavin formed is con-verted into Fi~q.

Medium containing high concentrations(150 mM) of phospha te s upporte d uniformlyspread mycelial growth. Low phospha te concen-trations supported only relatively scanty andgranular growth. Microscopic examination ofE. ashbyii grown in high phosphate showed thinlong mycelia with cytoplasmic polyphosphategranu les (Fig. 2a). Typic al swoll en forms be-come predominan t (Fig. 2b) in E. ashb~ ii grownin low phosphate. The polyphospha te granuleswere more or less absent.

A number of mechanisms have been postu-lated to explain the effect of phosphat e onsecondary metab olism (Martin 1977). As the in-dustrial fer mentatio n of flavin coenzymes maybe preferred to riboflavin due to their directapplica bility and demand, it will be worth ex-ploiti ng nutritional or other factors to in-crease F~Z production by the industria lly im-porta nt and highly flavinogen ic mold E. ashbyii.

Acknowledgements. The helpful discussionwith Dr. H. S. Chhatpar is gratefully acknowl-edged.

F~. 2a and b. The morphological transitions inE. ashbyi~ in response to phosphate. Cells grownin (~) Hig h phos phat e (150 n~) and (b) low phos-phat e (0.O015 raM). The magnif icatio n was 430.E. ashbyii ceils grown in the presence of high(150 mM) a nd low (O.OO15 m94) pho spha te w erestained with Albert's modified stain. Photo-graphs of wet mounts were taken with a ZeissIkon Camera and Carlzeiss photomicroscope

ReferencesFazekas AG, Kokai K (1971) Extraction, purifi-cation and separatio n of tissue flavins forspectrophotometric determination. In: McCormickDB, Wright LD (eds) Method s in enzymology, vol18-B. Academic Press, New York London, pp 385-398

Kaplan L, Demain AL (1970) Nutriti onal studieson riboflavin overproduction by A. gossypii.In:Ahearn DS (ed) Recent trends in yeast re-search. Georgia State University Press,Atlanta, pp 137-159

Madia ~M, Mattoo AK, Modi VV (1976) Enz ymicconstitution, ribitol formation and flavino-genes is in E. ashbyii. Ind J Exp Biol 14:680-683

Martin JF (1977) Control of antibioti c synthesisby phosphate. In: Ghose TK, Fiechte r A,Blake grough N (eds) Advances in bioche micalengineering , vol 6. Springer, Berl in Heidel-berg, New York, pp 105-127

Mehta SU, Mattoo AK, Modi VV (1972) Ribitol andflavinoge nesis in E. ashbyii. B ioche m J130: 159-166

Recei ved January 14, 1980