Continous Fermentation1

7/29/2019 Continous Fermentation1

1/38


2/38

K5301 - 20081

2

3

4

5

6


3/38


4/38

Morton Coutts (1904-2004), father ofcontinuous fermentation

Morton Coutts' plan for continuous fermentation at DominionBreweries' Waitemata Brewery was patented as a world firstin 1956.


5/38

A system at which; Fresh medium is continuously being

supplied

Volume of culture is kept constant

Removal of culture at same flow rate asthe feeding rate

An extension concept of fed-batchFi, Xi, Si, Pi

Fo, Xo, So, Po

F, X, S, P

D.V = Fi = Fo 0, V = constantD = Dilution rate (T-1)

F = flow rate

X = biomassS = substrateP = productV = volume


6/38

Prolong exponential growth of batchculture

Condition of Medium; Growth is substrate limited

Growth is not toxin limited

Exponential growth will proceed until theadditional substrate is exhausted

A steady state will be achievedeventually

Under steady state condition;

Specific growth rate is controlled by

Steady state =Formation of new biomass isbalanced with the loss of cells

from the vessel


7/38

Continuous CultureDistinguished Characteristics

Microbial growth takes place understeady-state condition

Growth occurs in constant rate andconstant environment

Physical and chemical factors aremaintained constant

Factors can also be controlledindependently by operator


8/38

K5301 - 2008


9/38

K5301 - 2008

Growth curve of batch fermentation Growth curve of continuous fermentatio


10/38

K5301 - 2008


11/38

K5301 - 2008


12/38

INTRODUCTION An apparatus for the continuous cultivation ofmicroorganisms or plant cells

Made of two main parts :-a nutrient reservior-a growth-chamber

Nutrients are supplied continuously to the culture vessel

Residual nutrients and cells are removed from thevessel (fermenter) at the same rate by an overflow

Volume of culture in the fermenter remain constant

K5301 - 2008


13/38

The volume of the chemostat can be controlled either by using:

Figure 1: Apump

Figure 2: An overflowsystem

K5301 - 2008


14/38

The nutrient medium contains an excess of allgrowth factors except one, the growth-limiting

nutrient

The concentration of the cells (biomass) isdependent on the concentration of the growth-limiting nutrient in the medium feed

Increase or decrease in the concentration of thegrowth limiting factor is correspondingly expressedby increase or decrease in the growth rate of cells

Thus the desired rate of cell growth can bemaintained by adjusting the level of concentrationswith respect to the growth limiting factor and otherconstituents

BTK5301 -2008


15/38

K5301 - 2008

K5301 2008


16/38

To grow microorganisms on very toxic nutrients

To select mutants with a higher affinity to the growth-limitingnutrient

To select the species that are optimally adapted to thegrowth limitation and culture conditions in a mixed population

To study the properties of organisms at selected growthrates

To gather steady state data about an organism in order to

generate a mathematical model relating to its metabolicprocesses

K5301 - 2008

K5301 2008


17/38

Chemostat Production of Plantaricin C byLactobacillus plantarum LL441By: Barcena et. al. (1998)

Lactobacillus plantarum LL441-isolated from

homemade cheese whey Produces bacteriocin - Plantaricin C Characteristics of Plantaricin C:

-3.5 kDa-resistant to harsh environmental conditions

-active at pH values from 2.0 to 7.0-induces the formation of pores in the plasmamembrane of sensitive cells-considered to be a food preservatives

Case study 1 :

K5301 - 2008

BTK5301


18/38

Objective :

BTK5301 -2008

BTK5301


19/38

Plantaricin C was optimally produced

in chemostat Kept at pH 5.0, 300C,150 rpm

Dilution rate for different carbonsource:

-glucose : 0.05h-1

-sucrose : 0.10h-1

-fructose : 0.12 h-1

BTK5301 -2008

K5301 2008


20/38

K5301 - 2008

K5301 2008


21/38

Introduction

A continuous culture device in which a bacterialculture is maintained at a constant volume andcell density (turbidity) by adjusting the flow rateof fresh medium into the growth tube by means

of a photocell and appropriate electricalconnections.

If the turbidity tends to increase, the feed rate isincreased to dilute the turbidity back to its set point.

When the turbidity tends to fall, the feed rate is loweredso that growth can restore the turbidity to its setpoint

Most turbidostats use a spectrophotometer orturbidometer to measure the optical density forcontrol purposes.

K5301 - 2008

K5301 2008


22/38

Sketch of TurbidostatK5301 - 2008

K5301 2008


23/38

Turbidometer

also known as a nephelometer

Process;

light shines throughout sample of water

light strikes a colloid the light is scattered

bounce off the colloid

reflects upwards

light does not strike a colloid shines through the water sample.

The meter measures how much light isreflected off colloids in the liquid medium.

K5301 - 2008

K5301 2008


24/38

K5301 - 2008

K5301 2008


25/38

Case Study 2:

Highly improved turbidity sensors was used. Algal densitywas regulated by turbidity measurements and the growthrates were monitored. The regulation system allowed an

effective online process control.

The turbidostat is a very good tool for such experimentsbecause it functions optimally at maximum growth rates

The algal growth in the turbidostat is not limited bynutrients. This provides a better quality of live feed forrotifers in turbidostats than in chemostats

Its possibility to monitoring the growth process of algae androtifers

Algae and rotifer turbidostats:

studies on stability of live feedcultures

By: Walz et. al. (1997)

K5301 - 2008

K5301 - 2008


26/38

K5301 - 2008

K5301 - 2008


27/38

K5301 - 2008

K5301 - 2008


28/38

Advantages of continuousfermentation

High productivityAbility to relieve repression under specific

nutrient limitationThe distillery can be run at steady state

conditions and at set-points in control. Without fluctuations during operations,

utility requirements are constant, giving agreater economy in usage.

Reductions in manpower.

K5301 - 2008

K5301 - 2008


29/38

Disadvantages

Prone to contamination.

Cost of pumps, reservoirs, sterilizers,and controls is relatively high.

Economic benefits of improvedkinetics is small compared to cost offeed and preprocessing

K5301 - 2008

K5301 - 2008


30/38

K5301 2008

K5301 - 2008


31/38

K5301 2008

K5301 - 2008


32/38

K5301 2008

K5301 - 2008


33/38

I. Continuous cultivation of rumen

microorganisms, a system withpossible application to the anaerobicdegradation of lignocellulosic wastematerials (Huub et al., 1986)

II.A bioprocessing mode forsimultaneous fungal biomass proteinproduction and wastewater treatmentusing an external air-lift bioreactor(Bo et al.,2001)

Continuous industrial microbial processesare much less common than batchprocesses, but most biological waste

treatment steps are operatedcontinuously

K5301 2008

K5301 - 2008


34/38

Continuous fermentation has been

successfully applied in

brewing industry ( Dennis et al., 2000)

single cell protein production (King,1982).

K5301 2008

K5301 - 2008


35/38

530 008


36/38

K5301 - 2008


37/38

ReferencesBarcena, J.M.B., Sineriz F., De Llano, D.G., Rodriguez, A., and

Suarez, J.E. (1998). Chemostat production of plantaricin C by

Lactobacillus plantarum LL441. J.Appl. & Environ. Microbiol.,64:3512-3514

Walz, N., Hintze, T., and Rusche, R. (1997). Algae and rotiferturbidostats: studies on stability of live feed cultures.Hydrobiologia 358: 127132

Gijzen, H.J., Zwart, K.B., van Gelder, P.T. and Vogels, G.D..(1986). Continuous cultivation of rumen microorganisms, asystem with possible application to the anaerobicdegradation of lignocellulosic waste materials. AppliedMicrobiology and Biotechnology. 22:155-162

Jin, B., Yu, Q., and van Leeuwen, J.H. (2001). A bioprocessingmode for simultaneous fungal biomass protein productionand wastewater treatment using an external air-liftbioreactor.Journal of Chemical Technology & Biotechnology.76 (10): 1041 - 1048

OBrien, D.J., Roth, L.H., and McAloon, A.J. (2000). Ethanol

K5301 - 2008


38/38

Continous Fermentation1

Documents

Transcript of Continous Fermentation1