TYPES OF BIOREACTOR Dr Bhavesh Patel Principal V

TYPES OF BIOREACTOR Dr Bhavesh Patel Principal V P & R P T P Science College, Vallabh Vidyanagar

Back ground v A Bioreactor is one in which biological reactions takes place. v Bioreactor is also known as fermentor v Fermentation is an important reaction carried out by biological system, importantly by microorganisms. v Fermentation can be defined as an oxidation reduction energy yielding process where both oxidizing and reducing agents are organic compound. v The process of fermentation was first observed by Louis Pasteur who gave the concept of “Germ theory of fermentation”. According to him the fermentation is mediated by germs i. e. microorganism. (the process was originally considered as a chemical process)

Back ground v Previously the process of fermentation was considered as an anaerobic process where a sugar or starch containing substrate is converted in to alcohol with the help of yeast. v Present definition of industrial fermentation “Bioconversion of any substrate in to its product” is v Hence, any process that is mediated by biological system is known as fermentation. v Presently we are producing many products at industrial scale like alcohol, amino acids, vitamins, antibiotics, organic acids etc. (students must try to prepare a comprehensive list of products produce along with producer organisms)

Types of Fermentation v Fermentation is of two types namely, Surface and submerged v As the name indicate in surface fermentation the organisms tends to grow on surfaces. This type of process is mainly applicable to fungi and involve the use of solid or semisolid substrate. The present day process which involves the concept of surface fermentation is solid state fermentation. v The other type of fermentation involves the cultivation of organisms beneath the surface (submerged). Such process mainly involves cultivation of bacteria using liquid media. v Submerged cultivation can be carried out by two ways i. e. Batch cultivation and Continuous cultivation.

Typical Batch Reactor

Continuous fermenter

Continuous fermenter v Continuous fermentation represents an open system i. e. the system where nutrient addition and product harvesting is a continuous process. As against this batch cultivation represents a closed system, where every thing is added once and only gases are allowed to exchange from environment in between. v Continuous fermentation is also a submerged kind of process where organism present in a steady state i. e. log phase. This can be achieved by continuous addition of fresh nutrients and harvesting the fermented broth at the same time. v The above process can be handled using Chemostat and Turbidostat

Advantages of Continuous fermenter v Size of the fermenter reduced and hence establishment expenditure. v Inoculum is to be developed once v Low shut down period v Product is more uniform v Useful where high nutrients or high product accumulation is inhibitory for the growth v Effective use of manpower

Tubular fermenter/ Packed bed reactor v The performance of Batch & CSTF is dominated by suspended microbes. They often occur as large flocs. v In tubular fermenter the microorganisms exists as flocks or films. v Process with microorganisms adhering to support surface are chiefly used in the waste water treatment industry under the name “Trickling Filter”. v Vinegar, waste water treatment

Tubular fermenter

The Fluidized Bed Fermenter v It represents particulate fluidization. v This is a characteristic of beds of regular particles suspended in an up flowing liquid stream. v It has increase in porosity from bottom to top of the bed & decreased particle movement when compared with beds containing particles of constant size. v Used for Beer & Cider production. v Flow rate limited by wash out.

Fluidized Bed Fermenter

Tower fermenter/ Air lift fermenter v It is developed for continuous production of beer. v The fermenter consists of a vertical cylinder with an aspect ratio of approx. 10: 1 v The significant feature of tower is the progressive & continuous fall in the specific gravity of the nutrient medium between the bottom & top of tower. v It is difficult to control microbial hold up.

Tower fermenter/ Air lift fermenter

Tray fermenter

Solid substrate fermentation (SSF) v Fermentation process occurring in the absence or near-absence of free water. v SSF processes generally employ a natural raw material as carbon and energy source. v Solid substrate (matrix), however, must contain enough moisture. v Mostly used with fungi. v Examples of products of solid state fermentation include industrial enzymes, fuels and nutrient enriched animal feeds, Bioleaching, Bioremediation, Bio pulping etc

Advantages of Solid State Fermentation (SSF) over Submerged Liquid Fermentation (SLF) v The low availability of water reduces the possibilities of contamination by bacteria and yeast. v High level of aeration can be maintained v Provides natural environment for the growth of Fungi, which is the main candidate for SSF v The inoculation with spores (fungi) facilitates its uniform dispersion through the medium v Reactor with simple design is in use v SSF in most cases require low energy

Advantages of Solid State Fermentation (SSF) over Submerged Liquid Fermentation (SLF) v Polluting effluents volume are generally low v The product obtained in SSF have slightly different properties (thermo tolerance) v Easy downstream processing

Disadvantages of Solid State Fermentation (SSF) over Submerged Liquid Fermentation (SLF) v The substrate in most cases require pre treatment such as size reduction by grinding, physical, chemical or enzymatic hydrolysis, cooking and vapour treatment. v Bacteria are poor performer in SSF because of low free water v Monitoring of process parameters such as p. H, moisture content, substrate oxygen and biomass concentration becomes a problem v Agitation is not possible. Aeration is also difficult v Possibilities of contamination with other fungal spp. is always there

Main groups of microorganisms involved in SSF v Bacteria Clostridium sp. – Ensiling, Food Lactobacillus sp. – Ensiling, Food Streptococcus sp. – Composting Pseudomonas sp. – Composting Serratia sp. – Composting Bacillus sp. – Composting, Natto, amylase v Yeast Endomicopsis burtonii – Tape, cassava, rice Schwanniomyces castelli – Ethanol, Amylase Saccharomyces cerevisiae – Food, Ethanol

Main groups of microorganisms involved in SSF v Fungi Alternaria sp. – Composting Penicillium notatum, roquefortii – Penicillin, Cheese Lentinus edodes – Shii-take mushroom Plurotus oestretus, sajor-caju – Mushroom Aspergillus niger – Feed, Proteins, Amylase, Citric acid Rhizopus oligosporus – Tempeh, soybean, amylase, lipase Aspergillus oryzae – Koji, food, citric acid Amylomyces rouxii – Tape, casava, rice Beauveria sp. , Metharizium sp. – Bioinsecticide Rhizopus sp. – Composting, food, enzymes, organic acids Mucor sp. – Composting, food, enzyme

Application areas of SSF Economic Sector Application Examples Industrial Fermentation Enzymes production Amylases, amyloglucosidase, cellulases, proteases, pectinases. Xylanases, glucoamylases Bioactive products Mycotoxins, gibberellins, alkaloids, antibiotics, hormones Organic acid Citric acid, fumeric acid, itaconic acid, lactic acid Bio fuel Ethanol Miscellaneous Pigments, bio surfactants, vitamins, xanthan Biotransformation Traditional fermented food (Koji, sake, ragi, tempeh), Protein enrichment and single cell protein production, mushroom Food additives Aroma compounds, dyestuffs, essential fat and organic acids Bioremediation and Biodegradation Caffeinated residues, pesticides, poly chlorinated bisphenyls (PCBs) Biological detoxification of agro waste Coffee pulp, cassava peels, canola meal, coffee husk Agro- Food Industry Environmental control