What are industrial processes?

Industrial processes result in the manufacturing of products (biological products, such as enzymes, medicine) on a large scale using different methods, such as physical and chemical procedures. Few products such as pharmaceuticals, agricultural products, food items, etc., involve microbes and their enzymes. Such processes are termed industrial biological processes. Microbiology and biotechnology enable us to utilize the ability of microorganisms to produce enzymes, primary metabolites, and secondary metabolites, which in turn help to produce the desired products.

What are the requirements of industrial processes?

Industrial processes require some essential ingredients for biological and chemical reactions to take place and to enhance the yield. Manufacturing several products in industries is carried out with the help of bioreactors or fermenters, substrate or media, microorganisms, quality control, and yield separation.

Bioreactors/fermenters

A fermenter is a vessel to which the substrate and microorganisms are added for the reaction to take place and yield the product. Fermenters are of various sizes ranging from a volume of one liter to 10,000 liters. They are huge cylindrical vessels, mostly made up of stainless steel. Fermenters have optimized pH, temperature, and physical conditions like aeration, agitation, etc., to obtain the desired product. They have a thermal cooling jacket or baffles to control the extra heat generated during the reaction.

For aeration, they have spargers at the bottom through which the air bubbles enter the fermenter. Different types of spargers are available, namely, nozzle spargers, orifice spargers, and porous spargers. They are used according to the fermentation type and product required. For the agitation of the fermentation mixture, some impellers rotate at speed with the help of an electric motor.

There are ports for the temperature control and pH control of the fermentation broth, which are checked at regular intervals. These controls are often connected to computerized systems.

Types of fermenters

Some common types of bioreactors utilized in industries are listed below:

Continuous stirred tank bioreactor

• In this fermenter, the impellers continuously stir the mixture, thus providing uniform mixing for the fermentation broth. This provides an efficient gas supply to the growing culture and the broth, thereby improving the yield quality.
• Continuous agitation of the fermentation broth creates a homogenous environment in the bioreactor.

Airlift bioreactor

The airlift bioreactors have separate compartments; half of the side is sparged while the other is not. The former is called the riser tube, while the latter is called the downcomer tube.

• A liquid fermentation medium is continuously passed through the riser and downcomer tube passages, providing proper aeration. Airlift fermenters are highly energy efficient. They are used for the manufacturing of proteins and other pharmaceutical drugs.

Packed bed bioreactor

Packed bed bioreactors consist of layers of solid particles made up of porous or nonporous gels. A biocatalyst immobilizes this solid gel. A nutrient broth is continuously allowed to flow over the immobilized biocatalyst. The product formed flows out of the bioreactor along with this broth, which is collected.

Bubble column bioreactors

• The bubble column bioreactor has perforated plates or spargers at the bottom of the cylindrical vessel for aeration. This ensures the mixing and transfer of oxygen or other gas provided through the sparger. This type of fermenter lacks mechanical agitators. The flow rate of the gas influences the performance of product formation.

Photobioreactor

• The photobioreactors are long transparent tubes of glass made of commonly used transparent plastic. They are used for fermentation that requires sunlight. The products obtained in these reactions are mostly photosynthetic pigments like beta-carotene, astaxanthin, chlorophyll, etc.

Submerged fermentation is the most commonly used type of fermentation where the microorganisms contact the media or substrate. Solid-state fermentation is another type that gives higher stability and concentration to the end product.

Importance of microorganisms in industrial processes

Microorganisms play a major role in industrial processes. Strains of bacteria, yeast, and mold are used to produce various products. The culture used in fermentation may be Bacillus spp, Rhizobium spp, Acetobacter aceti, Penicillium spp, Saccharomyces cerevisiae, etc.

Fermentative bacteria include Enterobacter spp, Clostridium spp, Butyricum spp, and Magashaeraelsdenii. These bacteria can produce H₂ gas in anaerobic conditions. They can utilize different carbon sources, for example, starch, cellobiose, maltose, sucrose, etc. They are used to produce lactic acid, butyric acid, etc.

The photosynthetic bacteria used for industrial processes include Rhodobacter sphaeroides, R. capsulatus, R. sulidophilus, and Thiocapsaroseopersicina. These bacteria can use different waste materials like whey, distillery, and sewage water, and they can be used for water purification, production of bio-fertilizers, and bioremediation processes. They require a high spectrum of light for growth and multiplication.

Green algal species are also used to synthesize different-colored pigments, for example, chlorophyll, xanthophyll, etc. They can convert solar energy at about ten folds relative to other plants.

Substrate/media

In industries, the substrates used for fermentation include carbon sources, such as cellulose and starch-containing substances, and sugars, such as lactose, maltose, etc. The corn steep liquor and molasses of sugarcane are also used as substrates.

The nitrogen sources include soy meal, ammonia or nitrate salts, peptone, tryptone, etc. Enzymes like amylase, invertase, beta-glycosidase, etc., are also supplied.

Micronutrients and vitamins are added to the fermentation broth. Yeast extract is the common source of micronutrients. Inorganic metal ions such as iron, zinc, copper, manganese, and cobalt are also present in the carbon and nitrogen sources in trace amounts.

Along with the essential requirements, anti-foam agents are added to prevent frothing and foam formation. In wastewater treatment, sewage water is the substrate. In biogas plants, the substrate is the waste of cattle and other organic waste. The substrate concentration has to be increased to increase the yield.

Yield separation

The extraction and isolation of the products in biotechnological industries take place simultaneously in a continuous fermentation process. In batch fermentation, the product formed per batch is collected and then sent for further processing. The yield obtained from the fermenter is not pure; thus, it must undergo purification to prepare the sample for marketing.

Collection, precipitation, filtration, purification using distillation processes, chemical treatment, centrifugation, HPLC (high-performance liquid chromatography), and solvent extraction are some of the downstream processing methods.

Quality control

Quality assurance and quality control are important steps in industrial biotechnology. These steps ensure the quality of the product. These processes include fermentation, and contamination and unwanted debris in the final product must be scrutinized. The product extracted is checked for parameters such as pH, melting point, and moisture content.

Products of industrial processes

The products of industrial processes include the following:

Primary metabolites

Primary metabolites are the key components in maintaining normal physiological processes. They are involved in the growth, development, and reproduction of a living organism.

These metabolites are formed during the growth phase when the organisms metabolize energy. They are essential for proper growth. Examples of primary metabolites include ethanol, lactic acid, acetic acid (vinegar), etc.

Alcohol is the most common primary metabolite used for large-scale production. It is used for various processes involving fermentation products like beer and wine.

Primary metabolites are commonly used in industrial microbiology to produce organic acids like kojic acid and citric acid. Citric acid is produced using Aspergillus niger. It is commonly used in the pharmaceutical and cosmetic industries.

Food produced by fermentation

Fermentation is an anaerobic reaction that produces gas, alcohol, and acids as by-products. This is a result of the action of microorganisms used as the culture in the respective process. Mostly yeast and bacteria are used in the baking and beverage industries. The products produced using fermentation include bread, cakes (in the baking industry), alcohol, beer, wine (in the beverage industry), cheese, yogurt, probiotics, etc.

Alcoholic beverages like beer and wine have a particular concentration of alcohol in them. Different strains of yeast can tolerate different alcohol concentrations.

Most of the yeast strains tolerate 10% to 15% alcohol. Some yeast strains can tolerate about 21% of alcohol. After fermentation, the product is extracted and aged for about six months to one or more years in cold storage to improve its taste.

Cheese and yogurt are dairy products produced by fermentation using microbial cultures. These microorganisms convert the lactose sugars in milk to lactic acid. These cultures include strains of Lactococci, Lactobacilli, or Streptococci families.

Various types of cheese can be produced depending upon the type of culture involved, their addition at different steps, differences in flavor, and the aging process. The fermentation process is also used for the production of enzymes. The types of fermentation vary from solid-state fermentation to submerged fermentation.

Production of biomass

The nutrients essential for the growth of plants, such as nitrogen, phosphorous, and potassium, can be synthesized organically with the help of microorganisms like Rhizobium species, Azolla, Cyanobacteria, Azospirillum, Azotobacter, etc. Bacillus thuringiensis is the bacterium used to produce biopesticides and biofertilizers.

Wastewater treatment

Wastewater from the industries and factories can be treated using microorganisms and fermenters. The wastewater is treated step-by-step procedure, including primary treatment, secondary treatment, and tertiary treatment. The primary treatment involves screening, grit separation, and sedimentation. The secondary treatment involves using bacteria and other microorganisms that degrade the organic substances in water through steps such as clarification, sludge digestion, trickle filtration, and activated sludge digester. The tertiary treatment is the final stage of water treatment. The trickling water filters have microbes that digest the small organic particles in the water. The water is treated in three steps: primary treatment, secondary treatment, and tertiary treatment. The recycled water is then released into the river after treatment.

Benefits of industrial processes

• Industrial processes using biotechnology provide environment-friendly products like bioethanol, biobutanol, and other biofuels that can reduce the use of petrol by 20% to 80%.
• The use of microorganisms that secrete enzymes to bleach paper would reduce the excessive use of chemicals for bleaching the pulps in the paper industry.
• Biodegradable plastics or other materials can be obtained from natural waste materials like sugarcane, bagasse, or cornstalks using biotechnological approaches in industries.
• There are many applications of these processes in the production of paper, textiles, plastics, chemicals, fuels, and pharmaceuticals.

Disadvantages of industrial processes

• These processes need lots of investment in the research and development department.
• It requires resources like well-equipped laboratories, fermenters, media, etc., making it an expensive process.
• The products made through these processes, such as genetically modified organisms (GMOs), pesticides, biofertilizers, etc., are debated for their effectiveness.
• There are issues regarding the Bt brinjal and Bt tomatoes, due to which they are banned. The farmers are concerned that other wild brinjal species would be extinct if the Bt brinjal is used commercially. Also, scientists are concerned with the associated health risks and increase in antibiotic resistance due to genetically modified brinjal plants.

Common Mistakes

Cane molasses used as substrates are misunderstood as the leftover waste of sugarcane after the extraction of its juice. However, molasses is a dark black viscous liquid obtained during the production of sugar from sugarcane or sugar beet. The solid waste material left after juice extraction is called bagasse. It can be used in the papermaking industry.

Context and Application

This topic is significant in the professional exams for undergraduate, graduate, and postgraduate courses, especially for the following:

• Bachelor of Engineering in Biotechnology
• Bachelor of Engineering Industrial Engineering
• Bachelor of Technology in Production and Industrial Engineering
• Master of Science in Biotechnology
• Master of Science in Microbiology
• Master of Science in Industrial Biotechnology

Related concepts

• Fermentation
• Downstream processing
• Quality assurance/Quality control
• Product packaging

Practice Problems

Q1: Which of the following processes is/are performed by microorganisms during the treatment of wastewater?

(a) Degradation of organic load in water

(b) Reduction of nitrates to form nitrogen gas

(c) Oxidation of ammonia or ammonium ions to form nitrate

(d) All of the above

Correct choice: (d)

Q2: Which one of the following bacterial species is used in the production of biopesticides?

(a) Streptococcus

(b) Bacillus

(c) Pseudomonas

(d) Azolla

Correct choice: (b)

Q3: It is advantageous to carry out solid-state fermentation rather than submerged fermentation as __________________________.

(a) it does not require sterilization

(b) it does not use microorganism

(c) it requires sterilization

(d) it involves the solubilization of nutrients

Correct choice: (a)

Q4: Which of the following groups of bacterial species are used in cheese-making?

(a) Bacillus, Streptococcus, and Lactobacillus

(b) Clostridium, Streptomyces, and Lactobacillus

(c) Lactococcuslactis, Streptococcus, and Lactobacillus

(d) Lactococcuslactis, Bacillus, and Pseudomonas

Correct choice: (c)

Q5: Which one of the following bioreactors consists of layers of porous or nonporous gel?

(a) Airlift reactor

(b) Packed bed reactor

(c) Photobioreactor

(d) Bubble column reactor

Correct choice: (b)