Open AccessInfluence of N-limitation on Malic Enzyme Isoforms and Lipogenesis of Cunninghamella bainieri 2A1
Author(s) -
Aidil Abdul Hamid,
Salwati Shuib,
Ekhlass M. Taha,
Othman Omar,
Mohd Sahaid Khalil,
Abdul Kader,
Mohd Hafez Mohd Isa
Publication year - 2014
Publication title -
jurnal teknologi/jurnal teknologi
Language(s) - English
Resource type - Journals
eISSN - 2180-3722
pISSN - 0127-9696
DOI - 10.11113/jt.v67.1861
Subject(s) - gene isoform , ammonium , lipogenesis , biochemistry , chemistry , enzyme , isozyme , malic enzyme , tartrate , enzyme assay , lipid metabolism , dehydrogenase , organic chemistry , gene
The influence of the presence of ammonium ions in growth culture on malic enzyme (ME) isoforms activity and lipogenesis in Cunninghamella bainieri 2A1 was investigated. The fungus was cultivated in a nitrogen-limiting medium for 120 h at 30oC under two conditions. One of the cultures was intermittently fed with ammonium tartrate to maintain the ammonium concentrations above 0.5 g/L. The second culture was performed without any feeding to allow N limitation, thus promoting lipid accumulation. Activity staining of ME isoforms was carried out for both cultures. The culture which was not intermittently fed with ammonium tartrate achieved a maximum lipid content of 35% (g/g biomass) at 48 h. This culture possessed five ME isoforms (A, B, C, D and E) with isoform E showing a parallel correlation to lipid accumulation profile. In contrast, intensity of bands representing isoform D decreased as lipid accumulated. No appreciable differences of all other isoforms were observed. However, the culture which was intermittently fed with ammonium tartrate, accumulated only up to 16% lipid (g/g biomass). All isoforms were present but with a more pronounced activity of isoform D and a lower activity of isoform E was observed. These findings support further evidence that isoform E is the key isoform for lipid synthesis in C. bainieri 2A1.