Industrial Microbiology:

Strain & Screening

Dr. Amit Kumar Dutta, Ph.D

Important Factor

Production of StrainHighly Desirable to use a

Production Strain Possessing

Strain......!

It should

Be High Yielding StrainHave stable Biochemical CharacteristicsNot produce undesirable substancesBe easily cultivated on a large scale

Character of Strain Production

Screening

Isolation and Detection of highyielding species from the naturalsource material containing aHeterogeneous Microbial Populationis called Screening.

Screening Techniques

Many Screening Techniques

Usually Two Types of Screening Programmes

Primary Screening

Secondary Screening

Primary Screening

Consist some Elementary Testsrequired to detect and to isolatenew microbial species exhibiting thedesired property.

P/S needed in the case of other usefulmicrobial species(MOs capable ofproducing Organic Acids, Amines,Vitamins, etc).

Primary Screening

Evaluation of the Primary Screening inIndustrial Research Programmes maybe made by citing some specificexamples of Screening Procedures.

Primary Screening

Screening Procedures of P/S.

Crowded Plate Techniques

Auxanography Techniques

First Plate(A)

Second Plate(B)

Enrichment Culture Techniques

Indicator Dye

Crowded Plate Technique

Simplest Screening Technique employed inDetecting & isolating AntibioticProducers.

Preparing a Series of Dilutions of the soil orother source material for the Antibioticproducing Micro-organisms.

Limited Applications

Provides information regarding theinhibitory activity of a colony againstthe unwanted microbes.

Crowded Plate Technique

Auxanography

Largely Employed for detecting Micro-organisms.

Able to Produce Growth Factors Extra-cellularly

(Amino Acids, Vitamins)

Enrichment Culture Technique

Designed by Beijerinck, SoilMicrobiologist.

Isolating the desired micro-organisms from a Heterogenousmicrobial population present in soil.

Unwanted Micro-organisms areeliminated or Develop poorly sincethey do not find suitable growthconditions in the newly createdEnvironment.

Enrichment Culture Technique

Today this Technique has become avaluable tool in many screeningprogrammes meant for isolatingindustrially important strains.

Enrichment Culture Technique

Indicator Dye

pH indicating Dyes may be employed insome screening methods for detectingMicro-organisms capable of producingOrganic Acids, Amines.

Dyes like Neutral Red, Bromthymol Blueetc are added to the Poorly BufferedNAM.

This Differential Technique may alsobe employed to finding outwhether micro-organisms arecapable of certain microbialtransformations or not.

Indicator Dye

Secondary Screening

Strictly essential in any systematicscreening programme intended toisolate Industrially useful Micro-organisms.

Helps in Detecting really useful Micro-organisms in Fermentation Process.

S/S Gives answers to many questions(Final Sorting of Industrially usefulMicro-organisms).

Secondary Screening

Alternative Screening &Analytical Techniquescould be employed forthe isolation ofmicrobial isolatesimportant in theproduction of otherIndustrial ChemicalSubstances.

Thank You