Chapter 24 : Environmental Sustainability and Biotechnology

Figure 24.1

Nature's technologies. The frog (Hyla ebraccata) (A) and bat (Thyropteratricolor) (B) have evolved similar adaptations for maintaining a fixed location. All tree frogs differ from most other frogs by having dilated toe tips that act as suction cups. Most bats hang by their sharp claws when they roost in caves or trees, but the disk-winged bat roosts inside a large tropical plant leaf as it unfurls. These bats use suction cups on their wrists and ankles to protect the fragile leaves.

Figure 24.2

Controlling production with feedback inhibition. Cells can control the amount of products (A and B) they make because one product (B) inhibits the binding of enzyme (E) to its substrate (S), which is the precursor of B.

Figure 24.3

Controlling production with gene regulation. (A) Bacteria manufacture the amino acid tryptophan when none is available from the environment. (B) When environmental concentrations of tryptophan are high, bacteria do not need to synthesize it. Under those conditions, the tryptophan-repressor protein complex binds to DNA and prevents the transcription of genes involved in tryptophan biosynthesis.

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Figure 24.4

Extremophiles. The red stream has high concentrations of sulfuric acid and iron, but the green photosynthetic microbes can tolerate these extreme conditions. (Photograph by D. E. White, courtesy of U.S. Geological Survey.)

Figure 24.5

Discovering extremophiles.(A) A researcher collects samples from a hot spring in the hope of finding microbes with genes that can degrade cellulose at very high temperatures. (B) Back in the laboratory, the microbes are cultured on media containing cellulose as the sole source of carbohydrates. Colonies that grow can degrade cellulose. (Photographs by Mike Himmel [A] and Warren Gretz [B], courtesy of the National Renewable Energy Laboratory.)

Figure 24.6

Large-scale biomanufacturing. A large-scale biomanufacturing facility contains many bioreactors. (Image courtesy of the Evans U.S. Army Community Hospital.)

Figure 24.7

Biomanufacturing. The nutrients contain the raw materials that the production cells will convert into products. The conversion of inputs into products occurs in a bioreactor, which comes equipped with sensors for monitoring the key environmental factors—temperature, oxygen level, and pH—so that the process can be adjusted to maintain optimal conditions for product manufacture. The outputs contain not only the commercial product, but also a waste stream that must be separated from the product stream.

Figure 24.8

Biomanufacturing of proteins. In the example shown, the company is using a bacterial host cell to manufacture human insulin. The gene encoding insulin must first be isolated and inserted into a plasmid. The plasmid carries the insulin gene into a bacterial host cell. The host cell is cloned to increase cell and plasmid numbers. The recombinant host cells grow and reproduce in a 1-liter flask. Eventually, the microbial population is so large it must be transferred to a 5-liter bioreactor. The next stage can be quite tricky as the manufacturing process is scaled up to thousands of liters. The insulin-manufacturing facility (not drawn to scale) contains many 10,000-liter bioreactors.

Figure 24.9

Biofuels. The bus uses diesel fuel derived from soybean oil. (Photograph courtesy of the National Renewable Energy Laboratory and the Nebraska Soybean Board.)

Figure 24.10

From cornstarch to ethanol. The man is unloading corn at an ethanol plant. The starch in the corn will be broken down into corn sugar, which will be converted into ethanol. (Photograph by Warren Gertz, courtesy of the National Renewable Energy Laboratory.)

Figure 24.11

Biodegradable plastics. A process developed at the Pacific Northwest National Laboratory converts the carbohydrates in potatoes into building block monomers that are used as feedstock chemicals in manufacturing plastics, adhesives, and textiles. (Photograph courtesy of the Pacific Northwest National Laboratory.)

Figure 24.12

Cellulosic biomass. Biofine Corporation in Waltham, Massachusetts, has developed a process that can convert cellulose into a small organic molecule that can serve as a monomer for synthesizing many chemicals. (Photograph courtesy of the Pacific Northwest National Laboratory.)

Figure 24.13

A sewage treatment plant in Hawaii. (Photograph courtesy of the National Renewable Energy Laboratory.)

Figure 24.14

Bioremediation of a gasoline spill. Gasoline from an underground storage tank seeps through the soil to the water table. After the leak is stopped, the free-floating gasoline is pumped out to a recovery tank. Polluted groundwater is pumped into a bioreactor tank with oxygen, nutrients, and hungry microbes. After the microbes eat the gasoline, the mixture of clean water, nutrients, and microbes is pumped back into the ground so that more of the pollutant can be degraded.