Phosphate Limitation Conditions

Mitsukawa, N., Okumura, S., Shirano,Y., Sato, S., Kato, T., Harashima, S. and Shibata, D. (1 997) Overexpression of an Arabidopsis thaliana high-affinity phosphate transporter gene in tobacco cultured cells enhances cell growth under phosphate-limited conditions. Proceedings of the National Academy of Sciences USA 94, 7098-71 02. 

Haas and colleagues used saccharified waste potato starch as a carbon source for PHB production by R. eutropha NCIMB 11599 under phosphate-limited conditions. The researchers achieved 179 gl biomass, 94 gf PHB and reported the yield of total biomass from starch as 0.46 gg, the yield for PHB from starch as 0.22 gg" , and the volumetric PHB productivity as 1.47 gl h. Residual maltose accumulated in the fed-batch reactor but caused no noticeable inhibition (Haas et al. 2008). 

Wlien cells of R, sphaeroides grown under phosphate-limiting conditions were incubated with [l- C]methionine in a pulse-chase experiment, the label was very selectively incorporated into DGTS and diree unknown compounds 1-3. In compound 1, die label was higliest at the end of die pulse and then steadily decreased during the chase period. In compounds 2 and 3 which could not be properly separated by TLC, die label first increased and dien decreased suggesting a turnover process. In DGTS, the radioactivity continuously accumulated with time (Fig. la). 

Fig. 1 Pulsc-chasc experiments. Cells grown under phosphate-limiting conditions were incubated for 20 min with the corresponding substrates followed by a 120 min chase, a) L-[l- C]methionine b) L-[ ie//iv/- C]methionine c) L-[l- C]methionine in the presence of 160 pM 3 -deazaadenosine.

Escherichia coli [NiFe] hydrogenase 3 Membrane-associated component of the formate hydrogen lyase complex H2 production during fermentation H2 uptake under anaerobic conditions Anaerobiosis, carbon source limitation, phosphate limitation, molybdenum, nitrate, formate 7.8... 

XK activity decreased with the increase in oxygen limitation (Fig. 4a). XK is a key enzyme in xylose metabolism and fulfills the initial steps of xylose metabolism together with XR and XDH, to convert xylose to xylitol, and then to xylulose in series. After that, xylulose is phosphorylated and channeled into the pentose phosphate pathway. The deerease in XK activity could be another reason for the decrease in xylose uptake rate under oxygen-limited conditions. It was reported that overexpression of the XKSl gene encoding xylulose kinase significantly increased xylose utilization and ethanol production in recombinant S. cerevisiae [32]. 

Cell-wall formation in Saccharomyces cerevisiae appears to be the result of two main patterns of deposition of wall material, viz., around the whole periphery of the non-budding cells and mainly at the tip of the daughter cell, or at the cross-wall that separates dividing cells. Synthesis and secretion of j3-D-glucan is unaffected by inhibition of RNA and protein synthesis. Growth of S. cerevisiae under conditions of phosphate limitations results in a decreased content of D-glucan and increased protein content as compared with control cells. 

Dawson M, Maddox I, Brooks J. Evidence for nitrogen catabohte repression during citric acid production by Aspergillus niger under phosphate-limited growth conditions. Biotechnol Bioeng 1989 33 1500-4. 

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