Biotechnological production cultivation condition

Most biotechnological applications of methods for gene expression analysis were described for coli strains [124,127,129,133-135,139,187-189] due to their importance for heterologous protein production [6] and the resulting available wealth of information on cultivation conditions [2], cell physiology, genetics and metabolism [190]. However, applications to B. subtilis [128,191, 192], C. glutamicum [126,153], Streptomyces coelicolor [172] and the yeast S. cerevisiae [125,130] were also described. 

Microorganisms have been a subject of particular attention as a biotechnological instrument, and are used in so-called cultivation processes. Numerous useful bacteria, yeasts and fungi are widely found in nature, but the optimum conditions for growth and product formation in their natural environment are seldom discovered. 

In order to improve microbial production, serious attention was given to determine the effect of fermentation conditions on the production yield and on the polymers physicochemical properties. Generally, the yield and composition of the polysaccharide depend on the microbial species used, age of the producing microbial cells and growth, cultivation medium, and conditions. The chitinous compounds content also depends on the type of fermentation and extraction method. An increase in chitinous material can be obtained either by increased biomass yield or by an increase in the cell wall content of chitin/chitosan. A summary of the advantages and disadvantages of several biotechnological possibilities to produce chitin/chitosan can be found in Table 3.1. 

Biotechnological methods of hyaluronan production from bacterial strains involve cultivation in selected conditions where the polysaccharide capsule is formed during the stage of logarithmic growth on the surface of the bacterial cells. But at the stationary growing stage, HA can move into the cultural liquid and a capsule could become thin or disappears completely [30]. At the end of the process, up to 1-6 g of the desirable product could accumulate in 11 of the cultural liquid. HA accumulation could be controlled by the measurements of the viscosity of the cultural liquid. 

All of these samples thus taken must be cultivated in order to isolate pure strains which can then be studied for their bioactivity and, if necessary, for their chemical composition. Although biotechnology presents many exciting opportunities to produce interesting substances without having to invest resources in large-scale harvesting, one of the inevitable problems is that production quality and quantity depend heavily on the culture conditions... 

---