Contamination Problem in Fermentation Industry
Each and every industry that carries out the fermentation process may face contamination problem. If the fermentation media, tank or fermented product gets contaminated it results in great economic loss to the industry. So to avoid this contamination problem some important steps should be carried out.
Contamination in the fermentation process may occur due to
- Fermentation tank itself
- Improper sterilization of fermentation media
- Seals present in the fermentation tank
- Mechanical failure
- Improper sterile air supply
1} Fermentation tank itself
Fermentation tank used in a fermentation process may differ in its size. It may vary from small lab scale fermentation tank to large industrial scale fermentation tank. The fermentation tank is cleaned properly before and after fermentation. In the fermentation process, the fermentation tank is not sterilized separately. The complete fermentation media is added in the fermentation tank and then the fermentation tank and media are sterilized together by using different sterilization techniques listed below.
2} Improper sterilization of fermentation media
If the fermentation media is not sterilized properly it may result in contamination. Contamination of fermentation media may be prevented by proper sterilization. Sterilization can be carried out by different procedures like
- By Boiling fermentation media.
- By passing live steam by retention tube.
- By using Steam under pressure that is autoclaving.
Generally, fermentation media is sterilized by passing through retention pipe containing steam jet heater. The fermentation media having low pH, a low acid content, non-utilizable carbon source such as hydrocarbon do not need sterilization. There are some fermentation media like antibiotic production media. Antibiotic-producing media is highly nutritive and supports the growth of a large number of micro-organism so it is important to sterilize such media.
The synthetic media used in the fermentation process requires less time and temperature for sterilization as compared to crude media. Synthetic media are designed by using pure components and are aqueous in nature and non-turbid in nature so they carry less number of microorganism and be easily sterilized. As compared to synthetic media crude media are very viscous in nature and ingredients present in crude media have a high number of micro-organism as well as highly resistant spores. Due to the viscous nature of the crude media time required for heat penetration is more.
Fermentation media should not be excessively heated as excess heat can cause many changes in the nature of media. 1] Excess heating may result in burning of sugar.
2] Especially sugars and phosphates should be sterilized separately if they are sterilized together it may result in caramelization of sugar.
3] In case of fermentation media with acidic pH or alkaline pH if excess heat is applied the chemical nature of some media components may alter and become useless in fermentation.
If the fermentation media is not properly sterilized or it gets contaminated it may affect the fermentation process by various ways like
- Contamination may reduce the yield of a product as the microbes that contaminate the process utilize the nutrients present in fermentation media due to which the nutrients become less available to the fermentation organism.
- The contaminant changes the chemical nature of nutrients and makes them non-utilizable for fermentation organisms result in reduced yield.
- The contaminant can change the pH of media resulting in an adverse effect on the product and can cause foaming problems.
- Some contaminant can produce a toxic product which can inhibit the growth of the fermentation organism.
- If the redox potential of the media gets changed or altered it can adversely affect the growth of the fermentation organism.
- In some case, contaminant uses the fermented product as their substrate and destroy fermentation product.
- So after a specific time interval fermentation process should be checked for contamination.
3} Seal present in the fermentation tank
The most important thing is to check all the seals are intact after sterilization to prevent further contamination.
4} Mechanical failure
Mechanical failure may be one of the reasons for contamination in the fermentation tank. Mechanical failures may include a breakdown of machinery.
5} Improper air supply
Sterile air is supplied in fermentation tank in case of the aerobic fermentation process. Generally, contamination does not take place because of air entering in the fermentor is sterile air. Aerosols are formed during aeration and agitation and escape the tank with air and may foul the packing around the impeller and allow the possible entry of contaminant. The contamination at this point is checked by steam steal.