Transcript mg td
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 m= specific growth rate m max 1/2 m max Ks = substrate concentration Residual substrate conc. [s] As growth increases biomass increases: during log phase dx = mx dt 1 dx. 1 dt x x = cell conc (biomass) (mg/m3) t = incubation time (h) m = specific growth rate (h-1) =m dx dt m =slope x Beginning of log phase t=0 biomass X0 On integration of equation 1 ∫dx x = ∫ mx Loge X = mt + K (integration constant) 2 when t=0 Log X0 = K put this value in equation 2 loge X = mt + loge X0 Loge X –loge X0 = mt ln X X0 = mt ln X . 1 = td X0 m 3 When t = td X = 2X0 Then ln X . 1 = td X0 m ln 2X0 . 1 X0 m ln 2 m = td = td 0.693 = td m m = 0.693 td m is inversely proportional to td If td is high m is low and vice versa X0 cells inoculated at time t0 X cells at time t dx = mx dt Can be written as equation 3 ln X X0 = mt 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 = m max s (Ks +s) m= specific growth rate m m max 1/2 m max 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 Stock culture collections Source Screening Primary screening Secondary screening Environment (soil) 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 1. Storage at reduced temperature a. Agar slopes at 50C or in -200C freezer: viable for 6 months b. Liquid nitrogen (-1960C): problems of refilling, advantages 2. Storage at dehydrated form a. Dried cultures b. 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 Antibiotics Essential metabolites Amino acids Nucleosides vitamins Ethanol, acetone, lactic acid, butanol Steroids Amino acids Alkaloids Gibberlins Pigments Metabolic end products Bioconversions Ascorbic acid