Make your own free website on

Lecture notes

Industrial microbiology
Home- 1st page
Page 2
Page 3
Page 4
Page 5
Page 6
Page 7

Industrial microbiology.


         Use of microorganisms grown on large scale for production of valuable commercial products/ to carry out important chemical transformations

         originated with alcoholic fermentation processes-wine, beer

         developed for pharmaceutical agents (antibiotics), food additives (amino acids), enzymes, chemicals - butanol, citric acids.

         New era- microbial biotechnology - manipulation of genes give new microbial products most not naturally produced by microbes

         biocatalysts - use of microorganisms as microbial catalysts for specific chemical reaction


Industrial Microorganisms and Products


         Major organisms use in biocatalytic processes- fungi (yeasts & mould) ; certain procaryotes - members of Streptomyces

         strains for industrial use of high metabolic specialization achieved - genetically altered via mutation/recombinant DNA hybridisation focussing on yield of particular product

         once strains developed then conserved by microbiological lab. Indusrty & in national culture collection - normally low yield strain deposited


Desirable Properties of useful industrial microorganisms:


         Produce substance of interest

         rapid growth and form product at short period

         genetically stable

         capable of growth at industrial scale & on inexpensive medium

         not harmful to human or economically important plants and animals

         produce spores/other reproductive structure for ease of inoculation

         easily manipulated genetically - mutation , selection


Examples of Industrial Products


            Growth and Product Formation in Biocatalyses - when in the growth cycle is the industrially useful metabolite produced?

         Two basic types of microbial metabolites:

1.      Primary - formed during exponential phase, cells and metabolite produced simultaneously eg alcohol(anaerobic metabolism of yeast & certain bacteria, as part of energy metabolism)

2.      Secondary - at or near stationary phase, after cells produced, further growth primary metabolite convert to secondary eg antibiotic


Characteristics of Secondary Metabolites


         Each only formed by relatively few organisms

         Not essential for growth and reproduction

         Formation dependent on growth conditions especially composition of media, repression of formation can occur frequently

         Often produced as group of closely related structures eg, spp. of Streptomyces produce > 30 related but different anthracycline

         Can often get dramatic overproduction compared to primary metabolites

         Product can be derived from primary metabolite not necessarily the primary substrate itself, therefore can get secondary metabolites from several intermediate products accumulating either in culture medium or cells during primary growth.


Antibiotics(substances produced by microorganisms that kill or inhibit growth of other microorganisms):

Isolation and Characterization:


         Produced by filamentous fungi and actinomycetes.(Streptomyces, Penicillins, Bacillus)

         Antibiotics classsified according to their chemical structure

         >8000 known antibiotic substances, several hundreds discovered yearly, more to be discovered

         Screening traditional means, however genetic engineering technique will permit artificially design new antibiotic -- eventually replace traditional screening method??

         Reality ? Currently computer model interaction between a drug’s target and modified version of a known drug, computer screen hypothetical drugs and predict  their efficacy, identified drug can be synthesised by  chemical or biological modification of existing drug, then tested for clinical effectiveness


Isolation and Screening of Antibiotic Producers Using Traditional Means

Other Microbial Products:


         Vitamins and Amino Acids

         Microbial bioconversion



         Citric Acid and Other Organic Compounds

         Industrial Use of Yeast-production of yeast cells, yeast products, fermentation products, beverage alcohol and distilled beverage