Advantages of Microorganisms for food production

ADVANTAGES OF USING MICROORGANISMS FOR FOOD PRODUCTION

Examination candidates should be able to explain the advantages of using microorganisms for food production rapid population growth, ease of manipulation; predictable and reliable product independent of climate; use of waste products from other industrial processes. These are listed on page 28 of the biology syllabus Aspects meriting particular emphasis include their prodigious population growth potential, their ability to grow on a range of cheap materials (which may otherwise be industrial waste) and the potential for processing of the raw product into a variety of nutritious formulations for specific purposes.

Illustrations such as the following may help students to appreciate the reasons for the interest in the potential for using microorganisms in food production

With a generation time of twenty minutes, and with no limiting factors, a single bacterium, with a biomass of only l0^-12g, would produce 22 x 10²⁵tonnes of biomass - 4000 times the mass of our planet - within two days. In other terms, a bacterium could, in a non-restricting environment, produce 10¹¹ times its own biomass of protein alone in a single day.

The potential for the application of modem biotechnology towards solving global food shortage, though a vast scenario, could form the basis of thought-provoking classroom discussion and/or topic work Widely different areas of exportable biotechnology are, of course involved. Some of the most significant developments are agricultural (such as the use of transgenic plants, animals and bacteria, of transplanted embryos and of micropropagation) but this is higher tier material. Teachers may prefer to limit discussion at this stage to the possible impact of microbial fermentation processes Many of the issues involved in the application of these processes are, in any case, common to other fields of biotechnological innovation.

Background

The global shortage of dietary protein has been particularly apparent since the 1950's. Animal protein is expensive to produce and this, together with other practical problems such as transport, the need for refrigeration and the dwindling of fish stocks, makes it largely unavailable in many developing countries. Supplying vegetable protein can be almost as problematic, especially in the face of soil impoverishment, drought and other adverse climatic circumstances.

In terms of energy efficiency, it clearly makes sense to use microorganisms, rather than conventionally-farmed animals or plants, to produce food. (Link with core work on trophic pyramids). Energy conversion factors, growth rates and technical feasibility are far from being the only considerations, however. Economic, political and social pressures may provide enormous obstacles. In the 1970's and 1980's, a number of companies tried to harness the astonishing potential of microorganisms to increase their biomass and their ability to grow on cheap organic foods. One idea was to produce animal food to replace imported soya bean and fish meal products. The most widely documented example is the ICI Pruteen^TM project. Investing well over £ 100 million, the company overcame formidable development problems to achieve a technological triumph. However, high production costs and falling prices of competing products meant that Pruteen^TM, although nutritionally excellent, was far more expensive than the imported materials it was meant to replace. The project had to be abandoned for these purely economic reasons and the plant was demolished. Attempts by other companies to produce microbial protein using oil as substrate failed following the steep rise in oil prices in the 1970's.

Other economic considerations come into play when attempts are made to replace imported materials, for the effects on the economy of the exporting country can be severe. Also, some countries which badly need more food and which have ample supplies of cheap carbohydrates which can be used as food in fermenters, cannot afford the high setting-up costs. Safety aspects are clearly very important; at present nearly all of the SCP products available globally are rigorous criteria regarding safety and nutrition, any novel material has to be acceptable in terms of taste, appearance and texture. Even the name of a product can deter consumers - for example, if it is implied that they are being invited to eat bacteria! The nutritional value of a food which no-one will eat is nil. Experience in food aid programmes has shown that nutrition problems could be solved by adding microbial protein powders to local traditional foods to be invalid Much attention is now given to these consumer-led aspects when presenting new foods. such as Quorn^TM.