Autotrophic cultures

Fig. 12. Relationship of sectional Chi content in segments and number of chloroplasts per unit area of vertical sections of hairy roots against mean distance from root tip. O photo-autotrophic culture at 1= 11 W/m2 for f=672 h, photomixotrophic culture at 1= 11 W/m2 for t= 240 h, A photomixotrophic culture at 1= 1.8 W/m2 for t = 240 h, V photomixotrophic culture at 1=0 W/m2 for t = 240 h. Open and close symbols present the sectional Chi content in segment and number of chloroplast per area of vertical sections of hairy roots, respectively...

Fig. 19. Relationships between root mass concentration and incident light intensity in photo-autotrophic cultures of hairy roots at 240 h ( ) and 1176 h (o)...

In the plant, the enzymes of the vindoline pathway, DAT (236,247) and NMT (242), are only found in the aerial parts, and in particular the leaves, the site of vindoline biosynthesis. In C. roseus cell cultures these enzymes cannot be detected, either after elicitation or in photoautotrophic or hormone autotrophic cultures (242). However, two enzymes of the early steps of the vindoline pathway, TllH and 11-O-methyltransferase are also present in cell cultures although at lower levels than in the plant (241). In the plant, the highest TllH levels are found in young leaves, whereas it is absent in stems and old leaves. 

Ren Q, Sierro N, Witholt B, Kessler B (2000) FabG, an NADPH-dependent 3-ketoacyl reductase of Pseudomonas aeruginosa, provides precursors for medium-chain-length poly-3-hydroxyal-kanoate biosynthesis in Escherichia coli. J Bacteriol 182 2978—2981 Repaske R, Mayer R (1976) Dense autotrophic culture of Alcaligenes eutrophus. Appl Environ... 

R. eutropha is actually an autotrophic hydrogen-oxidizing bacterium which can also produce poly(3HB) from C02, H2, and 02 [34]. The critical factor in such autotrophic cultivation processes is to avoid possible gas explosions. Therefore, a recycled gas, closed circuit culture system equipped with several safety features was developed and the oxygen concentration in the substrate gas phase was kept below the lower limit for gas explosions. A bacterial biomass of 91.3 g 1 1 has been achieved and the poly(3HB) content reached up to 67% per cell dry weight under these oxygen-limited conditions [35]. 

Autotrophic activity. Because of the low C N ratio and its declining value as carbonaceous residues are degraded there is substantial ammonification. With all mean treatment times greater than the doubling time of Nitrobacter sp. nitrification will occur provided that oxygen is not limiting. Smith and Evans (19) found that with DO levels above 15% of saturation, nitrification continued until the culture was limited by a fall in pH level. Up to 40% of the slurry ammonia was oxidised. The autotrophic activity never achieved steady state and cycled between periods of activity when the pH value was above about 5.5 and periods of inactivity when the pH value fell below 5.5. Complete nitrification of all ammonia only occurred if the pH value was controlled at about 7 by the addition of alkali. When the DO level was held within the range of 1 to 15% of saturation a system of simultaneous nitrification and denitrification was established. The reduction of nitrate allowed the pH value to remain above 6 and nitrification to continue. Thus more than 70% of the ammonia was oxidised. If the DO level was held below 0.1% of saturation, nitrification was inhibited (unpublished). 

Figure 10. Production of malondialdehyde, the change in Chlorella viability and uptake of O3 by a suspension of Chlorella cells. A sample from a culture of 38°C grown C. sorokiniana uflr. pacificensis (3 X10 cells/ml autotrophic medium) was treated with 180 ppm ozone. Thiobarbituric acid reactants were assayed by the method of Heath b- Packer (23), viable cells by plating on glucose-supplemented agar medium, and ozone uptake on a Cary spectrophotometer as described in Figures 6-8.

The medication is a sterile water extract from autotrophic bacteria Ferrooxidans spp. culture medium. It is a reddish liquid with acidic reaction (pH 3.0) and astringent action. The preparation does not cause irritation of tissues and is intended for external use. However, at present the possibility of its oral administration is being studied. 

Fig. 4A-C. Electron micrographs of thin sections of pak-bung hairy roots A photomixotro-phic hairy roots obtained from a 13 days culture in light at 7=11.1 W nr2) B, C photo-autotrophic hairy roots cultivated in the sucrose-free medium with 3.0% C02-enriched air supply for 30 days using conical flasks illuminated at 7= 11 W m-2 and shaken at 100 rpm. The abbreviations of 1-3 indicates a chloroplast-like structure with thylakoid membranes and grana stacks (1), chloroplasts (2) and cell walls (3), respectively...

There are differences in the pathways of thiamin hiosynthesis between prokaryotes and eukaryotes, and also between organisms that are aerobes and facultative anaerobes. Some organisms are completely autotrophic for thiamin, whereas others require the presence of either preformed pyrimidine or thiazole in the culture medium, and indeed some require both. 

Heterotrophic nitrification has been studied in terrestrial systems, especially acid forest soils, where it has been difficult to document autotrophic nitrification. Experiments using isotopes to differentiate production of N03 from inorganic and organic substrates in a forest system found that heterotrophic nitrification accounted for less than 10% of the total nitrification rate (Barraclough and Puri, 1995). No information of this sort is available on the occurrence or significance of heterotrophic nitrification in aquatic systems. The potential for NH3 and N02 oxidation by heterotrophic bacteria in aquatic systems warrants further exploration, and the capability may be present in many strains already in culture. If heterotrophic nitrification is common in nature, then a focus on autotrophic nitrification as the... 

---