Scaling up of batch sterialisation

Batch culture: Growth Kinetics During log phase growth reaches maximum (max) After depletion of substrate, growth rate decreases and finally ceases m = m max s (Ks +s) m= specific growth rate m m max 1/2 m max Ks = substrate concentration Residual substrate conc. [s]

As growth increases biomass increases: during log phase dx = mx dt dx. 1 = m dt x 1 x = cell conc (biomass) (mg/m3) t = incubation time (h) m = specific growth rate (h-1) dx dt m =slope x

Beginning of log phase t=0 biomass X0 On integration of equation 1 ∫dx = ∫ mx x Loge X = mt + K (integration constant) when t=0 Log X0 = K put this value in equation 2 loge X = mt + loge X0 Loge X –loge X0 = mt ln X = mt X0 ln X . 1 = td X0 m 2 3

When t = td X = 2X0 Then ln X . 1 = td X0 m ln 2X0 . 1 = td X0 m ln 2 = td m 0.693 = td m is inversely proportional to td If td is high m is low and vice versa m = 0.693 td

X0 cells inoculated at time t0 X cells at time t dx = mx Can be written as equation 3 dt ln X = mt X0 ln X –ln X0 = mt Converting natural log (log10 X –log10 X0) 2.303 = mt (log10 X –log10 X0) 2.303 = tt-t0 m (log10 X –log10 X0) 2.303 = m tt-t0

m max = m max s (Ks +s) m= specific growth rate m Ks = substrate concentration Residual substrate conc. [s]

Disadvantages of batch cultures Temperature of batch culture cannot be increased beyond 121oC In case increased Heating & cooling periods will increase Degradation of nutrients Problem overcomed by switching to continious sterialisation because Media to be sterialised is dealth in small increments Shorter heating & cooling period Lesser nutrient degradation

Development of industrial fermentation processes Money making Competition Economically feasible on large scale basis Recovery of product ready for open market Competitive advantage

What are the R&D approaches for finding of a MO of economic value, and large scale fermentation process? Micro-organism Source Stock culture collections Environment (soil) Screening Primary screening Secondary screening

Preservation of Industrially important MO Viable and Free from contamination Stored in such a way so as to eliminate genetic change and retain viability Viable by repeated sub-culture (avoid mutations by keeping stocks and strain degeneration and contaminations)

Preservation of Industrially important MO Storage at reduced temperature Agar slopes at 50C or in -200C freezer: viable for 6 months Liquid nitrogen (-1960C): problems of refilling, advantages Storage at dehydrated form Dried cultures Lyophillization Quality control of preserved stock: batch system, single colony, typical pattern, large number, purity, viability and productity If sample fails entire batch is destroyed

Types of Low molecular weight compounds by MO SUBSTRATE Primary metabolites Secondary metabolites Bioconversions Steroids Amino acids Ascorbic acid Antibiotics Alkaloids Gibberlins Pigments Essential metabolites Amino acids Nucleosides vitamins Metabolic end products Ethanol, acetone, lactic acid, butanol