Revealing the hexokinase step of glycolysis in lactic acid producer fungus Rhizopus oryzae

Alagoz, Eda
Acar, Seyda
Yucel, Meral
Hamamcı, Haluk
Rhizopus oryzae is a filamentous fungus which can grow on some renewable carbon sources and this makes it a good candidate for production of lactic acid and ethanol. However, in R. oryzae the production yields of these products are lower compared to alternative organisms. The utilization of the carbon source through glycolysis might end up in lactic acid or ethanol production. This makes the glycolytic pathway a focus of attention for our search for a way to increase the speed and efficiency of this pathway thus increasing the yield of desired end product. Hexokinase catalyse the first and irreversible step in glycolysis and implicated as one of the major control points in this pathway. In this study we are trying to investigate the regulation of glycolytic pathway of R. oryzae, in the light of studies done for Saccharomyces cerevisiae. The probable hexokinase genes were found from the annotated genome database of R. oryzae by doing a blast search using the known protein sequences of closely related S. cerevisiae hexokinases and glucokinase. Five of our ten probable hexokinase genes were obtained by using PCR. Sequencing results of three of them proved that these genes have no introns meaning they were expressed in R. oryzae. In the complementation study done in hexokinaless mutant of S. cerevisiae for one of these genes the growth of the transformant was observed on glucose or fructose containing media. Same experiments will be carried out for the rest of these genes.


Screening of the putative hexokinase genes from rhizopus oryzae
Alagöz, Eda; Hamamcı, Haluk; Yücel, Ayşe Meral; Department of Biotechnology (2013)
Rhizopus oryzae is a filamentous fungus which can ferment sugar to ethanol, and lactic acid. Increasing demand of the world for use of renewable carbon sources has put this and similar organisms into a position where the biotechnology industries are more and more interested with these organisms. R. oryzae can grow on some renewable carbon sources which makes it a good candidate for production of ethanol as well as lactic acid. The major use of lactic acid is in food industry and food- related application, w...
Investigation of sugar metabolism in rhizopus oryzae
Büyükkileci, Ali Oğuz; Hamamcı, Haluk; Department of Biotechnology (2007)
Rhizopus oryzae is a filamentous fungus, which can produce high amounts of L(+)-lactic acid and produces ethanol as the main by-product. In an effort to understand the pyruvate branch point of this organism, fermentations under different inoculum and glucose concentrations were carried out. At low inoculum size (1x103 spores ml-1), high amount of lactate (78 g l-1) was produced, whereas high ethanol concentration (37 g l-1) was obtained at high inoculum sizes (1x106 spores ml-1). Decreasing working volume i...
Investigating the effect of different factors on enzymatic hydrolysis of sugar beet pulp & corn cob
Leyluhan Yurtseven, Berna; Öztop, Halil Mecit; Department of Biotechnology (2019)
Hydrolysis of biomass obtained as the waste of industrial or agricultural production has gained significant interest in recent years. In this study, 2 different biomasses were studied. In the 1st part of the study, sugar beet pulp (SBP) hydrolysis was optimized using Response Surface Methodology (RSM). Sugar beet pulp is an important by product of sugar manufacturing and its hydrolysis could yield valuable sugars that can be used in fermentation processes. As the parameters of SBP hydrolysis by RSM, effect ...
Purification and characterisation of two isozymes of pyruvate decarboxylase from Rhizopus oryzae
Açar, Şeyda; Yücel, Meral; Hamamcı, Haluk (Elsevier BV, 2007-3)
Pyruvate decarboxylases were purified and partially characterised for the first time from aerobically grown Rhizopus oryzae mycelium. Two very similar pyruvate decarboxylase isoenzymes were partially separated from each other by a purification protocol including ammonium sulphate precipitation, gel filtration chromatography and anion exchange chromatography. The subunit molecular weights of the enzymes were estimated to be 61 kDa for both. The pI values determined by two-dimensional electrophoretic analysis...
Investigation of the effects of initial substrate and biomass concentrations and light intensity on photofermentative hydrogen gas production by Response Surface Methodology
Akman, Melih Can; Bayramoğlu, Tuba Hande; Gündüz, Ufuk; EROĞLU, İNCİ (2015-04-27)
Biohydrogen, which can be produced by dark fermentation and photofermentation processes, is a renewable and clean approach for hydrogen production. In this study, it was aimed to determine the operational conditions which satisfy the highest photofermentative hydrogen production rate in batch reactors. To that purpose, the effects of initial substrate concentration, initial volatile suspended solids (VSS) concentration and light intensity on photofermentation process, and their interactive effects were inve...
Citation Formats
E. Alagoz, S. Acar, M. Yucel, and H. Hamamcı, “Revealing the hexokinase step of glycolysis in lactic acid producer fungus Rhizopus oryzae,” NEW BIOTECHNOLOGY, pp. 0–0, 2012, Accessed: 00, 2020. [Online]. Available: