Culture and Growth

Bacteria have a number of requirements for growth. These include sources of energy, carbon, nitrogen, phosphate, sulfate, and various trace elements. They may include vitamins in certain cases. They also require to be grown at the correct 

The vast majority of bacteria of industrial and medical importance are heterotrophic (chemoheterotrophs). 

The terms obligate and facultative are also used obligate organisms can only use that form of nutrition, whilst facultative can switch from one form to another. The most common example of facultative organisms is the algae, many of which are photo autotrophs in the light, but may be chemoheterotrophs in the dark. 

Inorganic ions are also required, the most important ones being Mg , Fe2+/3+ Na+ Cr, and P04 -. 

Some species require the presence of vitamins and certain amino acids for growth. These are chemicals which the cell is unable to synthesise for itself and which must be supplied in the medium. 

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Ishio, M. Fujii, M., and Matsubara, S., Culture and growth of microorganism capable of oxidizing and decomposing sulfur compound contained in petroleum and biological desulfurization Patent No. JP7111900. 1995, May 02. 

A. L. Belousova and L. A. Popova (1961). The effect of inorganic phosphorus on tetracycline biosynthesis and the composition of phosphorus fractions in Actinoinyces atireofciciens with respect to the conditions of culture and growth of the mycelia (in Russian). Antibiotiki, 4, 302-307. 

MATERIALS AND METHODS Cell Cultures and Growth Conditions... 

Hwang, N. S., Kim, M. S., Sampattavanich, S., Baek, J. H., Zhang, Z., Elisseeff, J. Effects of three dimensional culture and growth factors on the chondrogenic differentiation of murine embryonic stem cells. Stem Cells. 2006, 24, 284-291. 

Cyanobacterial cultures and growth P. laminosum was grown at 45 C in medium D of Castenholtz (2). A. azollae was grown in a BG-11 medium without nitrate at 28 C. Both strains were cultured as previously described (3)... 

In these equations, [L = specific growth rate coefficient, v = specific rate of substrate uptake, t = time, x = biomass concentration, Sj = intracellular substrate, and Cj = concentration of intracellular substrate. Several examples where these equations can be applied include nitrogen hmitations in M. citrifolia cultures and phosphate hmited growth in C. roseus, N. tahacum, a.nd Papaver. somniferum. 

Continuous culture A method of eultivation in whieh nutrients are supplied and produets are removed eontinuously at volumetrieally equal rates maintaining the eells in a eondition of stable multiplieation and growth. 

As you might have already gathered, the majority of industrial fermentations are batch processes. In closed batch systems, the growth medium is inoculated with cells and growth and product formation is allowed to proceed until the required amount of conversion has taken place. After harvesting the culture the vessel is cleaned, sterilised and filled with fresh medium prior to inoculation. For some processes, addition of all the feedstock prior to inoculation, as is done in closed batch fermentations, is undesirable and it is preferable to incrementally add the carbon source as the fermentation proceeds. Such a process is known as fed-batch culture and the approach is often used to extend the lifetime of batch cultures and thus product yields fed-batch cultures are considered further in Section 2.7.4. 

A bacterium was grown as a glucose-limited chemostat culture and steady state growth yield (Yx/J was measured at different dilution rates. 

The system is balanced for cell growth by removing old culture and replacing it with fresh medium at the same rate. 

Miscellaneous Identified Inhibitors. 3-Acetyl-6-methoxy-benzaldehyde is present in the leaves of the desert shrub Encelia farinosa. It is apparently leached from the leaves and washed into the soil by rain. Concentrations of approximately 0.5 mg. per gram of dried leaf material have been measured. In sand culture studies, growth of tomato seedlings was inhibited by 50 p.p.m. while 115 p.p.m. reduced growth by 50% (53). A concentration of 250 p.p.m. killed the test plants within one day. The structure was confirmed by synthesis, and the synthetic material was shown to be as active as the natural product (54). Derivatives were also prepared in which a cyano, nitro, or amino group was substituted for the aldehyde moiety. The amino derivative was reported to be the most highly toxic. 

Biomass Production. Biomass is usually measured by dry weight of viable cells per unit volume X. We bypass the sometimes tricky problems associated with this measurement except to say that it is the province of the microbiologist and usually involves plate cultures and filtration followed by drying. Suppose there is one limiting nutrient S, and that all other nutrients are available in excess. Then the Monod model for growth is... 

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