Modern Industrial Microbiology and Biotechnology Use of industrial organisms in biotechnology through the followings: The first usage of industrial organisms is concerned with: Fermentation is defined as the type of metabolism of a carbon source in which energy is generated by substrate level phosphorylation and in which organic molecules function as the final electron acceptor generated during the break-down of carbon-containing compounds or catabolism. .

As is well-known, when the final acceptor is an inorganic compound the process is called respiration. Respiration is referred to as aerobic if the final acceptor is oxygen and anaerobic when it is some other inorganic compound outside oxygen e.g sulphate or nitrate.

The second usage of the term 'fermentation' is any process in which micro-organisms are grown on a large scale. Thus the production of penicillin, and the growth of yeast cells which are both highly aerobic, and the production of ethanol or alcoholic beverages which are fermentations in the physiological sense, are all referred to as fermentations.

The third usage concerns food such as cheese, bread, and yoghurt are fermented foods. Using of Industrial Microorganisms and other living cells in biotechnology Plants and animals as well as their cell cultures are also used in biotechnology. However, microorganisms have the following advantages over plants or animals: 1. Microorganisms grow rapidly in comparison with plants and animals. The generation time(the time for an organism to mature and reproduce) is about 12 years in man, about 24 months in cattle, only 15 minutes in the bacterium such as E. coli.

Some microorganisms that commonly used in Industrial Microbiology 2. The space requirement for growth microorganisms is small. 3. Microorganisms are not subject to the specific problems (weather) 4. Microorganisms are not affected by diseases of plants and animal. Some microorganisms that commonly used in Industrial Microbiology All living things are composed of cells, of which there are two basic types, the prokaryotic cell and the eukaryotic cell. Figure 1 shows the main features of typical cells of the two types.

Characteristics Prokaryotic cell Eukaryotic cell Nucleus Absent Present with nuclear membrane Organelles Present in a variety of forms DNA structure Single closed loop Naked strand with protein Multiple chromosomes Protein associated with DNA Chlorophyll When present, dissolved cytoplasm When present, contained in chloroplast Ribosome 70s 80s Cell wall Peptidoglycan Present in some types, absent in others Reproduction Binary fission By mitosis Examples Bacteria, rickettsiae, chlamydiae & cyanobacteria Fungi, protozoa, plants, animals & human.

Bacteria The bacterial phyla used in industrial microbiology and biotechnology are found in the Proteobacteria, the Firmicutes and the Actinobacteria. Proteobacteria: are major group of bacteria. They are Gram- negative bacteria. They include a wide variety of pathogenic bacteria such as Helicobacter, Vibrio and Escherichia. They include also free living bacteria, such as Nitrogen fixing bacteria (Bacteria able to fix nitrogen) and purple bacteria, produced reddish pigmentation and can take their energy from sunlight by photosynthesis.

They are characterized by the followings: 1- Gram negative bacteria having lipopolysaccharide in their cell wall 2- Some of these bacteria are motile; having flagella and others are gliding bacteria 3- They are heterotrophic, using organic compounds as a carbon and energy sources

4- Most of them are facultative or obligatory anaerobic bacteria 5- Proteobacteria are divided into: alpha; beta; gamma;delta and epsilon 6- Acetobacter and Gluconobacter (acetic acid bacteria) are the industrial organisms and are belonging to alpha proteobacteria.

Acetic acid bacteria They are Acetobacter and Gluconobacter bacteria. They have the following properties: 1- They do incomplete oxidation of alcohol into acetic acid (production of vinegar). 2- Gluconobacter lacks complete citric acid cycle, while Acetobacter have complete citric acid cycle and can oxidize acetic acid into carbon dioxide. 3- They can grow over acidic pH.

4- Acetic acid bacteria able to produce pure cellulose in unshaken culture. 5- Production of glucoronic acid from glucose, galactonic aicd from galactose and arabonic acid from arabinose. 6- Production of sorbose from sorbitol by acetic acid bacteria, an important stage in the manufacture of ascorbic acid (also known as Vitamin C).

Firmicutes They are Gram- positive bacteria, some of them lacking cell wall. They have low GC ratio. The G+C ratio is the ratio of Guanine and Cytosine to Guanine, Cytosine, Adenine, and Thymine in the cell. It is used to classify Gram-positive bacteria: low G+C Gram- positive bacteria (ie those with G+C less than 50%) are placed in the Fermicutes, while those with 50% or more are in Actinobacteria.

Spore-Forming Firmicutes 1- Aerobic bacteria : Bacillus. The most important is Bacillus thuringiensis which kills the larvae of mosquito, due to production of toxins. 2- Anaerobic bacteria: Clostridium spp.

Non-spore forming firmicutes The Lactic Acid Bacteria: The non-spore forming low G+C members of the firmicutes group, they are very important in industry as they contain the lactic acid bacteria. The lactic acid bacteria are rods or cocci placed in the following genera: Enterococcus, Lactobacillus, Lactococcus, Pediococcus and Streptococcus and are among some of the most widely studied bacteria because of their important in the production of some foods and pharmaceutical products.

Lactic acid bacteria are divided into two major groups: 1- Homofermentative group, which produce lactic acid as the sole product of the fermentation of sugars. 2- Heterofermentative, which besides lactic acid also produces ethanol, as well as CO2.

Use of Lactic Acid Bacteria for Industrial Purposes: The desirable characteristics of lactic acid bacteria as industrial microorganisms include: a. Ability to rapidly and completely ferment cheap raw materials. b. Their minimal requirement of nitrogenous substances. c. Produce high yields d. Ability to grow under conditions of low pH and high temperature e. Ability to produce low amounts of cell mass

Non-spore forming firmicutes (The Lactic Acid Bacteria) Characteristics of Lactic Acid Bacteria 1) It is the non-spore forming low G+C members of the firmicutes. 2)The lactic acid bacteria are rods or cocci placed in the following genera: Enterococcus, Lactobacillus, Lactococcus, Leuconostoc, Pediococcus and Streptococcus 3)They are among some of the most widely studied bacteria because of their importance in the production of some foods, and industrial and pharmaceutical products.

4) They lack porphyrins and cytochromes, do not carry out electron transport phosphorylation. 5) Gaining energy by substrate level phosphorylation. 6) They grow anaerobically but are not killed by oxygen. 7) They obtain their energy from sugars and are found in environments where sugar is present. 8) They have limited synthetic ability and hence are fastidious, requiring, when cultivated, the addition of amino acids, vitamins and nucleotides.

Lactobacillus & Streptococcus are examples of lactic acid bacteria involved in many in food fermentations (fermented milk, cheese & fermented vegetables).

Heterolactic fermentation Homolactic fermentation A) Glucose degraded via EMP(Embden–Meyerhof–Parnas) pathway to lactic acid as the only end product. - 1glucose + 2 ADP + 2 P 2 lactic acid + 2 ATP B) It is carried out by Streptococcus, Pediococcus, Lactococcus, Enterococcus and various Lactobacillus species. C) It is important in dairy industry yogurt & cheese. Heterolactic fermentation One molecule of glucose via pentose phosphate  one molecule of lactic acid +one molecule ethanol & one molecule CO2.

The difference between Homofermentative lactic acid bacteria & Heterofermentative lactic acid bacteria 1) The absence of the enzyme aldolase in the heterofermenters. Aldolase is a key enzyme in the E-M-P pathway and splits hexose glucose into three-sugar moieties. 2) Homofermentative lactic acid bacteria convert the D-glyceraldehyde 3- phosphate to lactic acid. 3) Heterofermentative lactic acid bacteria receive 5-C xylulose-5 -phosphate from the Pentose pathway. 4) The 5-C xylulose is split into glyceraldehyde 3-phosphate (3-C), which leads to lactic acid, and the 2-C acetyl phosphate which leads to ethanol.

Prepared by: Dr. Lina Jamil