T I B T E C H - A U G U S T 1 9 8 9 [Vo l . 7]

Agricultural biotechnology: growing concern?

During a recent conference* on biotechnology and sustainable agri- culture (see Table 1 for definitions), two hundred scientists, agriculture industry representatives and environ- mentalists agreed on one thing: the development of biotechnology must proceed cautiously and thoughtfully to ensure that the results fit the needs of the environment, farh~ "~ and society as a whole. The coL.len oe was sponsored by the National Agricultural Biotechm.~ogy Council, a consortium of research institutions funded originally by the Joyce Foun- dation and the US Department of Agriculture.

'The ways in which biotechnology is used and developed are crucial because the tools of biotechnology offer those who wield them the opportunity to shape agriculture, the environment and society' said Chuck Hassebrook of the Center for Rural Affairs, a rural interest group in Nebraska.

Hassebrook's remarks were drawn from his recently published report, which outlines alternatives for mesh- ing biotechnology, family farming and the environmentL He said that society must get control of biotech- nology and technological research if it wants to preserve rural communi- ties, family farms and the environ- ment rather than allowing such control to concentrate in the hands of corporate interests.

However, maintaining societal control of biotechnology research means that society must question the research that receives public and private funding. Society also must inject its own goals into research agendas. A key question in the debate over what research should or should not be carried out is 'who benefits?' Hassebrook said that agricultural research should focus on creating opportunities for people to own and

*Biotechnology and Sustainable Agri- culture: Policy Alternatives, Iowa State University, Ames, Iowa, USA; 22-24 May 1989.

operate their own farms. A large body of research indicates that such farm- ing systems preserve a more egali- tarian social structure than that found on large industrial farms where managers and laborers often are on vastly different educational and social planes. Small farming systems also create more stable -ommunities.

By focusing on owner-operated farms, biotechnology could be made to work with sustainable agriculture instead of against it. Industrial-type farms often harness and work the land with no thought for preserving resources for the future.

Hassebrook gave a number of examples of the ways in which the directions of biotechnology and sus- tainable agriculture were out of synchrony. Farm chemicals, for example, have been a key to indus- trial agriculture. However, while many researchers claim biotech- nology could eventually reduce dependence on such chemicals, the emphasis of current biotechnological research simply trades biotechnology for chemicals instead of working towards systems of sustainable agriculture.

The use of Bacillus thuringiensis against certain insect pests, corn borers, is one such trade-off. Corn borers tend to persist mainly in fields where corn is planted year after year in a monocrop system typical of industrial, non-sustainable agricul- ture. Research on B. thuringiensis mainly benefits large one-crop systems at a time when scientists and public policy makers should be looking for ways to control pests that persist in the soil despite cultivation, crop rotation or other land manage- ment practices.

Development of herbicide-resistant crops could also lead to practices contrary to the goals of sustainable agriculture. Hassebrook said herbi- cide-resistant plants would actually increase the demand for chemicals and reduce the use of mechanical weed control. A better method of fighting weeds, and a method more

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Not for the first time, concerns about the effects of biotech- nologieal developments on agriculture are being voiced; this time, in Iowa, by scientists, farmers and environmentalists (see accompanying article by J. Anderson). Given that con- flict is newsworthy and that, as u 1987 Office of Technology Assessment (OTA) survey indicated, the general public are more inclined to believe environmental groups than federal agencies or companies, we can expect more, and more vocal, protest. In response to a growing mood of discomfort, with biotechnology, it will be increasingly important for re- searchers to judge whether their work is socially defensible and, then, to defend it.

JOIIN HODGSON, TIBTECII

suitable to sustainable agriculture, would be the development of crop varieties tolerant of mechanical cultivation.

There are many ways in which biotechnology could aid sustainable agriculture if the will were there. Research to increase tolerance of corn and sorghum to cool spring weather would allow these crops to grow more rapidly and gain advantage over emerging weeds. The development of alternative crops such as alfalfa, oats and grasses could reduce the dependence of farmers on major cash crops such as corn and wheat.

Gary Comstock (Iowa State Univer- sity) mentioned numerous signs that indicate research to develop herbi- cide-resistant plants conflicts with sustainable agriculture. One such indicator is that many chemical companies have acquired seed com- pany interests and are funding research on plants resistant to their herbicides with the goal of marketing the herbicide and seed together.

Rebecca Goldburg of the Environ- mental Defense Fund, a public interest research group that monitors environmental issues, said that research on herbicide-resistant plants actually promotes herbicide use, detracting from the move away from heavy agricultural chemical use. Chemical companies argue that the new generation of chemicals like Roundup and Scepter are less toxic

T I B T E C H - A U G U S T 1989 [Vol. 7]

- Table 1

Definitions used in conference:

the

Biotechnology: the application of molecular biology to the develop- ment of useful products and processes.

Sustainable agriculture: the appropriate use of crop and live- stock systems and agricultural inputs supporting those activities which maintain economic and social viability while preserving the high productivity and quality of the land.

and are used in smaller amounts. However, not all of the effects of these herbicides are known, and some researchers have already begun work on designing plants resistant to older, more toxic herbicides such as Atra- zine, which has been found in high levels in Midwestern wells. With research on herbicide-tolerant trees and grasses already under way, herbicide use could eventually expand into a treatment for weeds in large forests and along roadsides.

David Pimental (Cornell Univer- sity, Department of Insect Ecology and Agricultural Sciences) said cautions also extend to the develop- ment of biological pesticides, or biopesticides. For instance, bio-

pesticide-producing organisms and herbicide-resistant plants could become entrenched in the environ- ment, displacing other species. 'Once you get the organism in nature, the odds of your ever getting them back are practically nil', Pimental said. He cited those crop plants brought into the USA from other countries as crops. Today, 127 such crop plants, including pigweed, have become agricultural pests. However, Pimental said research on insect-fighting organisms should continue, because they do offer the potential to benefit sustainable agriculture if handled properly. The primary goal of such research would be to reduce the use of chemical pesticides while still controlling crop losses to insects, which last year destroyed an esti- mated 12% of the US corn crop.

The compatibility of animal growth hormones with sustainable agri- culture was also discussed. Bovine somatotropin, which increases milk production by up to 25% in dairy animals, is expected to be approved by the US Food and Drug Ad- ministration for farm use early in 1990, said Robert Kalter, a Cornell

economist. Increasing milk pro- duction may, however, harm the dairy industry rather than help it, re- spondents argued. The costs of such hormones could also push out smaller dairy farmers and leave the industry in the hands of industrial-type farmers, contrary to the goals of sustainable agriculture.

While biotechnology research can be made compatible with sustainable agriculture, public input is required to guarantee that the new products made in the laboratory do not become the undoing of land, water and genetic resources and the individual- ized farming systems and associated small communities that remain the foundation of agriculture.

Reference 1 Hassebrook, C. and Hegyes, G. (1989)

Choices for the Heartland: Alternative Directions in Biotechnology and Impli- cations for Family Farming, Rural Communities and the Environment Center for Rural Affairs, Walthill, NE 68O67, USA.

]ULIE ANDERSON

4725 California Street #6, Omaha, NE 68132, USA.

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A need for systematic investigations into the material

properties of cultured animal cells

Liquid mixing is used in cell culture and fermentation processes to help achieve a variety of process ob- jectives, such as dispersing cells or bubbles, increasing mass transfer or preventing cells from settling and attaching to vessel walls.

The mixing of liquid components (which may contain gas bubbles, cells or other solids) is the result of velocity gradients and shear forces between the components. These forces may also cause cell damage,

or, at least, effect changes in a variety of cell processes (e.g. DNA synthesis, receptor-mediated endocytosis, the secretion and possibly formation of proteins1-3). Shear damage is of par- ticular concern for animal and plant cells, but is also important for some fungat and bacterial fermentations. Damage may occur in operations such as mixing and sparging in bio- reactors, continuous centrifugation, cross-flow filtration, pumping or cell homogenization. It is therefore

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important to know the extent to which cells may be affected by the operating conditions.

Physical shear indicators Reactor design .and engineering

requires estimates of the shear stress which correlate with the various operating conditions, such as im- peller speed, sparging, medium properties etc. and which can be extrapolated to various reactor scales.

Calculations of shear stress in reactors are based on liquid vis- cosity, in combination with a vel- ocity parameter such as impeller tip speed, bubble velocity or liquid velocity. These calculations provide broad estimates for hydrodynamic shear stress conditions (e.g. maxi- mum shear stress, wall-zone shear stress, bulk shear stress etc.). The