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A new approach to reaching rural areas with biotechnology

Romeo V. Alicbusan
Microbiological Research Department, National Institute of Science and Technology, Manila, Philippines

A new approach to industrialization
Farm modules
Advantages and disadvantages

Processes in biotechnology transfer to rural communities

Communication of technology and its demystification
In situ development and local participation

Processes in transferring biotechnology to rural communities

Biotechnologies appropriate for rural communities
How biotechnology transfer might function


Beginning in 1974, the National Institute of Science and Technology (NIST) has intensified the outreach programme aimed at development of rural communities in the Philippines. Biotechnological food preservation and production activities are being conducted in the country's 13 regions. The objective is to teach biotechnology to interested individuals and for them to use the knowledge for their own domestic needs. They are also expected to develop home and cottage industries using locally available raw materials

Considering the total land area of 300,700 sq km, divided into 7,100 islands with a population of 47 million and 111 linguistic, cultural, and racial groups, the outreach programme during the past five or so years has hardly penetrated the target sector of society.

It is lamentable that, in spite of significant numbers of available low-cost technologies developed in various government agencies, including NIST, relevant information seldom reaches rural communities. Lack of a better mechanism for spreading these technologies, coupled with political, social, cultural, and economic constraints, is the primary reason for this shortcoming.

Rural communities are basically agricultural, with a large number of tenant farmers. Per capita income is usually 18 to 20 per cent lower than the national average, which affects literacy. Fifteen per cent of the rural population is illiterate compared with 2 per cent in the urban sector. lt has been estimated that 70 to 75 per cent of unemployed labourers are in the rural sector. With limited land resources coupled with high illiteracy, increased productivity can only be achieved through the combined inputs of money, land, fertilizers, labour, planting materials, better handling and marketing of produce, and low-cost technologies. There are many problems in the rural communities, but their potential for development cannot be ignored.


A new approach to industrialization

To develop an industry such as mushroom production, there must be available capital, an abundant supply of raw materials, manpower, technology, a sufficient and constant volume of the product, and an efficient marketing system. Considering these important components of industrialization, one of the best approaches to encourage private entrepreneurs to become involved in such a project is to prepare a feasibility study for them. In the feasibility study, the amount of capital needed, the pay-back period, and the return on investment - including the projection of activities shown in figure 1 - would probably be convincing enough for enterprising people to engage in business.

From the schematic diagram of operation (fig. 2), it can be seen that there are two types of farming - corporate and community - each employing two methods of production - the indoor and outdoor systems. The corporation must adopt the whole scheme in order to reach the required volume of production with lower investment in a relatively short period of time.

First, the corporation engages in its own corporate farming, adopting both indoor and outdoor methods. The reason for this is to maximize the use of bedding materials and space. The production cycle in both cases is 22 days, but outdoor production is started at least 22 days before the indoor one. When production from the outdoor beds has been completed, 30 per cent of the spent substrate is then put inside the growing house, steamed, spawned, and given the necessary care to grow mushrooms inside the growing houses. The indoor method requires a quarter of the space the outdoor type demands.

Another reason for corporate farming is to have a sure source of mushrooms in the event that community production should fall short of the target volume because of inclement weather or other reasons. Also, a corporate plantation shows contract farmers that the corporation is not totally dependent on them, otherwise farmers might force unacceptable terms on the corporation and business could not prosper.

In preparation for the establishment of a mushroom industry in communities, illustrated hand-outs in both English and the vernacular are given to selected university graduates who are trained by the research and development staff in the different aspects of mushroom production.


Farm modules

Before the establishment of demonstration farm modules, preliminary studies were made, Surveys were conducted on the available resources in a pre-determined area with regard to manpower, economic conditions in the village, availability of raw materials for mushroom beds, water supply, political organizations, the market potential of the town, as well as the people's aspirations. Questionnaires were prepared and filled out in co-operation with community inhabitants. The data were collated and analysed and a final decision was made as to whether or not a farm module would be appropriate.

FIG. 1. Mushroom Farm Module Operation and Cost/Benefit Analysis

FIG. 2. Mushroom Enterprise Operations

The corporation rented an area for a farm demonstration module and selected two villagers to work on the farm as employees of the corporation. This demonstration module became the show-window of lowcost technology for mushroom production and subsequently intensified interest among the villagers. It is the aim of the corporation to sustain the interest generated by providing some inputs that the farmers could pay for from their produce.

Planting two mushroom beds a day for a total of 44 beds in a 22-day production cycle would give an income of P1,500 to P2,000 (US$205 to $273) per month. This level of income is comparable to that of senior researchers at NIST.

Farm modules are open to the public. Charts of the economics of production are reporoduced and distributed free to interested farmers. Those desiring to set up their own farm modules are accepted for training only after payment of a P200 fee. They have to work on the farm without pay but are given free food. While training, they have to learn the rudiments of running the farm. The training lasts for two weeks - long enough for the trainees to see the results of their work.

The rationale for exacting a training fee is, first, to discourage the obviously curious, and, second, to make the trainees take their work more seriously and learn the techniques in a relatively shorter period. It has been a common experience in the transfer of technology that most things given free are not seriously regarded by the recipients even if they are for their own benefit.

When the training is complete, and farmers have signified their intention to develop their own mushroom farms, a contract is signed between the corporation and the farmers. The corporation sends its technicians to extend technical assistance in siting, laying out the farm, preparing an operational plan, and initial planting of the beds. The corporation supplies the spawn, plastic sheets, chemicals, and sprayers on credit. Payment for these items is deducted from the income from the mushroom harvest. Under this arrangement, the farmer merely provides the lot, bedding materials, and labour. The corporation buys the produce on the farms at a previously agreed upon price.

Mushroom contract farmers who continuously engage in mushroom production for six months without any financial obligation to the corporation receive back their training fee of P200 without interest. By this time, the farmers have already saved enough money to buy all the supplies needed on the farm.

As the contract farmers acquire more experience in operating a farm module of 44 effective beds, they can develop other modules, using their own resources. No new modules, however, can be set up without prior clearance from the corporation. This is necessary in order to prepare the necessary production inputs - i.e., mushroom spawn, plastic sheets, chemicals, etc. - coming from the corporation, and also to prepare the market for additional harvest.

Technical problems in mushroom production are referred to the corporation for immediate solution through roving technicians or letters. Problems beyond the competence of the corporation's research and development staff are relayed to government research institutions for rapid disposition.

Initial production in corporate community farming, which is understandably limited, is usually given away free to political and civic leaders of the village and to other people. This system is part of the effort of the corporation to educate people on the palatability of the product.

Mushrooms are picked at the right stage. Picking is usually done at three-hour intervals. The harvests are cleaned of soil and bedding debris, graded according to size, and packed in 1 kg perforated plastic bags. To keep the mushrooms fresh at the button stage, packages are placed inside styropore baskets with crushed ice. The ice is contained in waterproof plastic bags to avoid wetting the mushrooms. The low temperature preserves the mushrooms fresh for 48 hours.

The corporation obtains the mushrooms from the farms for centralized marketing in urban food markets. Farm modules in the outlying areas of metropolitan districts are assigned to sell fresh mushrooms. Farmers in far-away places that require more than three hours' travel one way are told to dry the mushrooms.

Knowing the financial status of some contract farmers, the corporation adopts a cash-and-carry basis for transaction. To maintain the quality of the products, a grading system is introduced with corresponding prices.

This method of biotechnological transfer to rural communities was recently adopted by a newly formed corporation dealing in mushroom production in the Philippines.


Advantages and disadvantages


  1. The common financial problems of rural communities are partly solved because the corporation can extend some production inputs on credit.
  2. The supply of mushroom spawn (spore), which is one of the major contraints encountered by mushroom-growers, is solved by the corporation.
  3. Marketing problems associated with a highly perishable product like mushrooms are solved because the corporation buys all the product right on the farms.
  4. Technical assistance to mushroom-producers can be extended with more dispatch than by government departments.
  5. The involvement of rural communities provides job opportunities, better utilization of agricultural wastes, and, in turn, the corporation reaches the desired volume of production in a shorter period of time with less expense.



  1. Not all interested individuals can be given the opportunity to engage in mushroom production because of some limitations in economically obtainable sources of bedding materials.
  2. The quality of the produce is rather hard to maintain due to varying conditions of growth in different mushroom communities.
  3. The type of management varies from place to place because problems obtaining in one mushroomgrowing community are not necessarily the same in others, hence a case-to-case basis is needed for problem-solving.
  4. Owing to several factors affecting production, the target yield is not usually attained. This is primarily because of lack of sufficient experience by the farmers. An unstable volume of production has an adverse effect on the marketing system.

More advantages and disadvantages will be encountered in the future. This is to be expected because of the biological nature of the business. It is comforting, however, that early indications from five mushroom-producing communities suggest that this novel approach is feasible.



Alichusan, R,V. "Mushroom Production Technology for Rural Development." In Bioconversion of Organic Residues for Rural Communities (IPWN-1 /UNUP-43), pp. 99-104. United Nations University, Tokyo, 1979.

____. "Countryside Development through Optimized Utilization of Resources with Appropriate Technologies." Lecture delivered during Unesco Regional Training Course, Bandung, Indonesia, 8-24 Jan. 1979.

____. "Profile of Philippine Resources and Technology Diffusion Efforts for Their Utilization." Paper submitted to UNU-sponsored workshop, Philippines, 1978.

____. "Community Development Is the Answer to the Present Economic Crisis." Paper read on 39th Foundation Day, San Pablo City, Philippines, 7 May 1979.


Processes in biotechnology transfer to rural communities

C.V. Seshadri
Shri A.M.M. Muragappa Chettiar Research Centre, Madras, India

The notes presented here are from the Indian experience in transferring biotechnology to rural communities. The lessons to be drawn from these notes have to be translated to suit use locale, i.e., specific factors in other areas. In fact, this is true even for widely separated areas in India. In a sense, then, this suggests why technology transfer is seldom a technological process. We shall examine why this is so and point out the means-to improve the situation.


Communication of technology and its demystification

Technology has to be communicated to rural people who make no distinction between work and leisure, who have been practicing some form of biotechnology for hundreds of years, and who have no margin for failures. To such people technology is usually transmitted on two false premises: (a) it is an end, not a means, and (b) the know-how is more important than the know-what and the know-when. One can recognize that these premises have led to many wrong decisions in developing countries, and we shall not elaborate on this in detail other than to give some examples. To communicate properly the right priorities in technology and to explain them clearly to rural communities, the best scientific talent has to be constantly available in the rural milieu where the technology is to be practiced. This means that the scientist must live there. Three examples will help illustrate the point:

  1. The farmers need irrigation water. "Let us build a big power plant to supply them with electricity." This is a typical example of a technology's becoming an end in itself, not a means. Very little thought is given to transmission losses, fuel shortages, pollution, unequal water-table lowering, etc.
  2. The farmer wants a biogas plant. There is no point in worrying him about the microbiology of the process or about trying to reach maximum efficiency of gas generation. He should be told, however, what sort of return he can expect according to different circumstances.
  3. The farmer needs more information. "Let us get him some from published sources." This kind of attitude completely begs the question that science is transferred by reprints and technology by people.


In situ development and local participation

Usually even the simplest technology, when practiced at a rural level, needs adaptation to local conditions. For example, when considering a biogas plant, one may not find a good valve for miles and so will have to substitute a reconditioned local one. Thus, the development process invariably involves local innovation. This development is essential to the proper flowering of technology. In fact, the occurrence of errors and their correction, all taking place in front of the village, is helpful in giving people selfconfidence. This naturally leads to the question of local participation. Unless people see that things are fabricated and processed locally, the technology is difficult to transfer. Development in situ eliminates the problem of technology transfer.

In demonstrating the experience of transferring technology to rural areas two case studies are presented which have been prepared for teaching purposes. These case studies are backed up by detailed notes and calculations that are submitted to students and are also accompanied by a slide presentation.

Biogas Plants

Currently available biogas designs are very expensive, even though there is a considerable government subsidy. Therefore, the effort in transferring this technology has been to make low-cost designs available. Consider the following factors:

Materials needed Availability and associated factors
- Bricks Very expensive and deliveries uncertain
- Steel plate Unavailable in village areas and impossible to weld
- Steel rods Available in nearby townships
- Cement Available but of uncertain quality
- Lime Freely available
- Pipe fittings Available in townships
- Sand, stones, etc. Available
- Plastic sheets Available in townships
- Lumber Available
- Masonry, carpentry, and skills Available

The choice of materials, skills, and machines has to be matched to the village habitat. The design methodology and design calculations for two types of biogas plants are discussed in detail in notes given to the students.

Algal Culture at the Village Level

The aim of this teaching programme has been to maximize protein output per unit of land and water. For this algae cultures via photosynthesis offer the best solution. The lecture is accompanied by about 30 slides and roughly 20 pages of detailed notes. Some of the highlights of the programme are as follows:

  1. It is best if you can identify a local filamentous species that is easily harvestable and of high food value. Otherwise an international species has to be obtained. Harvesting is a very expensive step for single-celled species.
  2. A central laboratory to maintain healthy, if not axenic, cultures is necessary. Also, laboratory instrumentation is necessary to monitor pH, contamination, etc. At the rural level, some skill transfer is called for to keep cultures healthy and to follow the necessary procedures.
  3. The technology of making small ponds and filtration devices is explained.
  4. Solar driers or cookers to subject the harvested algal slurry to temperatures up to 100°C are required.
  5. The medium for culturing algae must be adapted to local conditions.
  6. Techniques for using the algal dry mass are explained.


Processes in transferring biotechnology to rural communities

P. L. Rogers and R.J. Pagan
School of Biological Technology, University of New South Wales, Sydney, Australia



The transfer of technology to rural communities in a way that will benefit their neediest members is one of the major challenges of our generation. The problem is how to translate technologies that we have available into suitable forms for village use and to promote them for the rural poor. A low standard of living seems to breed mistrust of outsiders and promote conservatism (1). The rural poor cannot afford to take risks; newness means unreliability; poverty saps energies and narrows the horizons of the possible.

Experience has demonstrated that uncritical technology transfer is likely to benefit only a minority rather than to improve the lot of the larger community (2). It is fundamental to be aware of the sociological structure, educational level, and cultural orientation of a particular community in order to bring about effective and equitable technology transfer (3; 4).

Any consideration of technology transfer to rural communities should begin by identifying the fundamental needs and aspirations of their people. Questions should then be asked as to how technology transfer might assist in meeting these needs. Some of the needs are very basic: food, shelter, clothing, medical services, land ownership, employment. Others, such as education and the need to make full use of all the natural resources available to the community, reflect rising aspirations and the desire to improve living standards and distribute benefits more widely.

Technological innovations can assist in meeting some of these needs and aspirations, and some form of technology transfer is clearly desirable for many communities. Well-planned and identifiable programmes designed for a particular country and region are necessary, as highlighted by recommendations from the UN Conference on Science and Technology for Development (UNCSTAD) in Vienna.

The development of a technology to meet particular needs may arise in a number of ways: (a) the reviving of old techniques previously used within the community; (b) the adaptation/improvement of existing (indigenous) methods; (c) the acceptance of and adaptation of modern technology; (d) the development of new techniques relevant to a particular situation.

The concept of "appropriate technology" is useful when considering which techniques are likely to be adopted by a rural community. Appropriate technology may be defined in terms that emphasize smallness, simplicity, and low capital costs; it provides work-places with minimum capital investment. The implanted technology is likely to be more complex and efficient than traditional technologies, but simple enough for village labourers. It must be designed to provide knowledge, training, machinery, and employment at prices and levels that can be assimilated by the simplest of communities.

Programmes of technology transfer (or, more appropriately, "technological innovations at village level") require planning at the national level but implementation at regional and village levels. The education of key village personnel in the new methods will play a vital role in such programmes, as has been illustrated by the Saemaul ("new village") movement in Korea. The village should also be educated in the benefits of such programmes and encouraged to develop innovative methods for other areas of need within the rural community.


Biotechnologies appropriate for rural communities

Biotechnology in its broadest sense is concerned with processes or process steps in which biological agents are used. Processes involving micro-organisms fall within this category, and are of major interest in the present discussion. Areas of biotechnology relevant to rural communities can be identified as: (a! bioconversion of lignocellulosic and carbohydrate wastes to provide energy, and to provide food and feed; (b) simple wastewater treatment; and (c) upgrading of foods and beverages produced by fermentation of indigenous raw materials. As the present workshop is concerned with bioconversion, our discussion will focus on this.

The following raw materials may be available to rural communities for bioconversion through fermentation:

FIG 1. Enzymatic Conversion of Delignified Rice Straw to Sugars (ref. 5)

Conversion of Cellulose and Starch to Sugars for Fermentation

Although organisms exist that can degrade cellulose and starch directly, the most efficient way to convert these substrates into yeast (single-cell protein) or ethanol (as a liquid fuel supplement) is first to convert the cellulose and starch to sugars. Acid hydrolysis can be used, but enzymatic processes are proving increasingly attractive. Such processes are shown in figures 1 and 2. The kinetics of cellulose conversion by two different enzymes for delignified rice straw are illustrated in figure 1 (5). The kinetics of starch hydrolysis using a two-step enzymatic process are shown in figure 2. A heat-stable enzyme such as Termamyl (Novo) will liquefy the starch at 80° to 90 following cooking. After a period of one to two hours, amyloglucosidase is added (60° C; pH = 4.5) to saccharify the resultant dextrins and oligosaccharides to produce fermentable sugars.

The data illustrate the rates of hydrolysis that can be achieved with commercial enzyme preparations. At the village level, rather than purchasing commercial enzymes, simple barley malt, raggi, or koji-type processes could be developed.

FIG. 2. Enzymatic Conversion of 30 Per Cent Starch Slurry to Sugars Using Two Enzyme Processes

Ethanol Fermentation and Yeast Growth

Ethanol fermentation and yeast growth on various carbohydrates have been selected for discussion here, as other papers are concerned with low-technology processes for algal biomass, fermented foods, and methane production.

Fermentation ethanol from indigenous raw materials is likely to provide significant quantities of liquid fuel in the future. Already Brazil, the United States, and the Philippines have embarked on programmes to convert agricultural crops (e.g., sugar cane, sugar beets, cassava) into ethanol. In Australia, a number of rural communities growing sugar cane, sugar beets, and wheat are evaluating the production of fermentation ethanol to meet local fuel needs. Similar situations apply in New Guinea, Fiji, and the South Pacific islands, many of which have abundant supplies of carbohydrates but no oil.

In the same way that methane is generated by anaerobic digestion in rural communities (e,g., India, China) to meet some local energy needs, fermentation ethanol could be produced in small-scale processes to supplement the available liquid fuels. Ethanol can be blended with petrol in proportions of 1 to 20 per cent and no major engine modifications are required. Higher ethanol blends are being tested with motor vehicles and farm machinery.

Yeasts are traditionally used for fermentation, although recent research in our laboratories on an organism used in making tropical alcoholic beverages (tuak in Indonesia) has shown considerable promise. In figure 3 the kinetics of ethanol production for Zymomonas mobilis on 25 per cent glucose are compared with Saccharomyces carlsbergensis (uvarum), a yeast selected for its sugar and ethanol tolerance and ability to flocculate. Although yeasts are probably the most suitable for small-scale batch fermentations, Z. mobilis has specific rates of ethanol production and glucose uptake two to three times higher than yeasts and would be advantageous for high-productivity continuous fermentations (6).

Within the farming community in Australia, simple, low-cost processes are currently being developed for the conversion of farm wastes and substandard grains into fermentation ethanol. They depend on grinding or sprouting the grains, followed by cooking and enzyme addition. This is then followed by a yeast fermentation to produce 8 to 9 per cent w/v ethanol and distillation to 96 per cent ethanol suitable for blending. The distillation is achieved either through a wood-fired still or a solar still using radiant energy. It is evident that such a process could be adapted fairly readily to rural communities elsewhere.

Modifications to low-technology situations include the use of local barley malt, raggi, or koji preparations to replace commercial enzymes, and the use of various nutrient sources, such as paddysoak water, to provide nitrogen and minerals (7). The design of simple fermentors, such as tower fermentors that concentrate the yeast by internal recycle (8-10), and the development of low-cost materials (plastics, fibreglass) for the fermentor and holding tanks minimize the capital costs.

The residual yeast produced in the fermentation is also likely to be of value as a protein-enriched supplement for animal feed. It could be concentrated to a slurry by solar drying for easier addition to animal feed.

Traditional Enzyme Preparation

The conversion of starches to yeast-fermentable carbohydrates may be accomplished in several ways. Malting is the common practice in brewing with cereal grains. The use of a variety of moulds is common in preparing many Oriental foods. Koji, the best known, is a general term for moulded masses of cereals or soybeans. These materials serve as a source of enzymes, and in some cases as an inoculum. There are a number of types of koji, depending on their use, but Aspergillus oryzae is the mould generally used. A specific koji is prepared for each type of product in order to produce the proper mixture of amylolytic, proteolytic, and lipolytic enzymes, Raggi and Java yeast are used in Indonesia and consist of rice flour containing fungi, yeast, and bacteria. Certain strains of Mucor, Rhizopus, and other moulds have been isolated from these preparations 111).

FIG. 3. Production of Ethanol from 25 Per Cent Glucose Using Zymomonas mobilis and Saccharomyces carlsbergensis (uvarum )

The development of small-scale equipment for solid substrate fermentations, such as would be involved in traditional enzyme production, is discussed in detail by Hesseltine (12; 13),

As outlined earlier, the village-level manufacture of malting enzymes, koji, or raggi should be encouraged in order to supplant the need for commercial enzymes for starch hydrolysis.


How biotechnology transfer might function

Once a particular project that involves a fermentation process at village level or within a rural community has been identified, it is clear that an effective educational programme is fundamental for its success. Key personnel within a community need to be trained both in the new techniques and in the likely benefits, Such people will then disseminate information within their community. Close liaison and cooperation should be maintained with policy-makers and scientists at centralized tertiary institutions

Facilitating biotechnology transfer within the South-East Asian region are a group of young scientists who have been trained in the adaptation of fermentation processes to regional needs. This has come about through the very successful operation of a regional microbiology network established following a Unesco meeting on Regional Co-operation in Basic Sciences in South-East Asia held in Tokyo in 1974. There have been a number of training courses related to nutritional and environmental problems and the effective use of natural resources (listed in the Annex below).

The problem that remains is to translate this knowledge to the village level and to research techniques for scale-down of fermentation processes. Seshadri (14) points out that two requirements need to be met for widespread propagation of bioconversion methods: {a) cheap fermenter designs, and (b) culture or inoculum banks to supply starter cultures. Encouragement to villagers to produce their own source of enzymes, using traditional methods, could be added.



The dramatic and continuing interest in "appropriate technology," founded on Schumacher's ideas and idealism, has focused on the village and the rural poor as prime targets for technological innovation. The technology need not be radiacally new or different to have immediate and far-reaching effects on lifestyle, morale, and living standards of a community.

Biotechnology in a primitive form - fermentation of alcoholic beverages (e.g., tuak), preservation of foodstuffs (e.g., tempeh) - has always been carried out in villages. Modern biotechnology can, given suitable agricultural residues or effluents from processing agricultural materials adjacent to a rural community, lead to a significant and valuable upgrading of either protein or energy content. This is especially relevant in these days of unstable oil prices and high levels of inflation.

Although the economics of production may be favourable, it is evident that strong governmental support is required. As illustrated by the US Department of Energy report "Alcohol Fuels: Policy Review" (June 1979), stimulation of private-sector, small-scale ethanol production from agricultural residues will require a number of government incentives, including low-cost loans, research and development grants, excise tax exemption, and so on. It is not unreasonable to consider that similar incentives will be required to stimulate biotechnology transfer within South-East Asia and elsewhere

Besides fiscal intervention from the government, technology resource pools specifically designed to transfer information on products and processes to villagers should be set up both within and among various countries. These information networks must be designed to provide technological data quickly, efficiently and with minimum cost to both the user and the government, and, of paramount importance, any new technology must be seen by the people who will use it as something both trustworthy and beneficial.


Annex: Training Courses Related to Biotechnology within the Regional Microbiology Network for SouthEast Asia (Sponsored by Unesco, UNEP, and ICRO)

Conservation and use of micro-organisms for waste recovery and indigenous fermentations - Bandung, Indonesia, August 1974.

Microbial protein production from natural and waste products - Bangkok, Thailand, April 1976.

The role of microbiology in the management and control of the environment - Manila, Philippines, November 1976.

The role of micro-organisms in waste recovery, fermentation, and environmental management - Singapore, November 1977.

Environmental management - biological waste treatment and by-product utilization - Seoul, Korea, July 1978.

Training courses in applied microbiology and fermentation technology (sponsored by the Government of Japan) - Osaka, Japan, 1974-1979.


1. P. Devitt, in Internatl. Devel. Rev., 2011): 16 119781.

2. E. Schumacher, in Futurist, 11: 93 (1977).

3. G.S. Ramaswamy, in Internatl. Devel. Rev., 18 (2): 7 (1976).

4. R. Darling, in Internatl. Devel. Rev., 19 (4): 27 (1977).

5. N. Toyama and K. Ogawa, in T.K. Ghose, ea., Symposium on Bioconversion of Cellulosic Substances into Energy, Chemicals and Microbial Protein (Indian Institute of Technology, New Delhi, 1978).

6. P.L. Rogers, Kye Joon Lee, and D.E. Tribe, in Biotechnology Letters, 1 (4): 165 (1979).

7. K. Bose and T.K. Ghose, in Process Biochemistry, 8 (2): 23 (1973).

8. F.K.E. Imrie and R.N. Greenshields, in Proceedings of the 4th International Conference, GIAM (São Paula, Brazil, 1973).

9. S.J. Pirt, Principles of Microbe and Cell Cultivation (Blackwell Scientific Publications, Oxford, U K, 1975), pp. 45-48.

10. F.K.E. Imrie and R.C. Righelato, in G.C. Birch, ea., Food from Waste (Applied Science Publishers, London, 1976), P. 79.

11. C.S. Pederson, Microbiology of Food Fermentations (Avi Publishing Corporation, Westport, Conn., USA, 1971).

12. C.W. Hesseltine, in Process Biochemistry, 12 (6): 24 (1977).

13. C.W. Hesseltine, in Process Biochemistry, 1 2 (9): 29 (1977),

14. C.V. Seshadri, Analysis of Bioconversion Systems at the Village Level, Monograph Series on Engineering of Photosynthetic Systems (Shri A M.M, Murugappa Chettiar Research Centre, Madras, India, 1978).