Nitrogen-limited cultures

The requirement for oxygen and carbon source for cell biosynthesis are calculated using nitrogen-limited mass balance equations for growth during exopolysaccharide production 01 res (nitrogen-limited cultures). These balances are derived from experimentally determined values of ... 

K. Miyamoto PC. Hallenbeck, JR. Benemann (1979) Solar energy conversion by nitrogen-limited cultures of Anabaena cylindrica. J. Ferment. Technol., 57 287-293... 

Figure 4. Effect of Mn supplementation on the appearance of extracellular MnP activity. Nitrogen-limited cultures were grown from a conidial inoculation. Extracellular MnP activity from cultures grown in the presence (open triangles) or absence (open circles) of 180 fiM MnSO was assayed as described (13.32). Dry weights of mycelia grown in the presence (solid triangles) and absence (solid circles) of Mn were also determined. (Reproduced with permission from Ref. 32. Copyright 1990. American Society for Microbiology.)...

Figure 2. Effects of carbon and nitrogen limitation on the production of LiP and MnP activities. Carbon limited cultures ( ) Nitrogen limited cultures ( ). Carbon limited cultures contained per liter 0.66 g diammonium sulfate and 2 g glucose. Nitrogen limited cultures were the same as the controls. They contained 0.2 g diammonium tartrate and 10 g glucose. All cultures received 11.2 ppm Mn(II).

Cell Growth. Mycelial pellets of P. chrysosporium (ATCC 24725) were produced under nitrogen limited culture conditions at 37°C using a spore inoculum (36). The pellets were grown for 72 hr at 150 rpm after which they were concentrated fourfold by decanting excess medium. They were used for reduction experiments after a 24 hr activation period (37°C, 50 rpm, under 100% O2 atmosphere). 

Low level phosphate (0.5-5.Og/L) in a chemically defined medium is required for maximum CA yield. The presence of excess phosphate leads to a decrease in carbon dioxide fixation, an increase in the formation of certain sugar acids, and growth stimulation. Kubicek and Rohr (1977) showed that CA accumulated whenever phosphate was exhausted even when nitrogen was not limited. Nevertheless, chemostat cultures performed under dual phosphate/nitrogen limitation produced results very similar to those from a nitrogen-limited culture. ... 

Poly(3HB-C6>-3HP), produced by R. eutropha and A. latus as noted above, has also been synthesized by a soil isolate of Methylobacterium [117]. In nitrogen-limited cultures containing methanol as the main carbon source (0.5% (v/v)), the addition of 3-hydroxypropionate led to accumulation of the copolyester. The 3HP fraction in the polymer could exceed 10 mol%, but total copolymer content in the cell was always below 12%. 

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