Bacteria can also remove sulfur from coal before it is burned and help clean up toxic dumps. Transgenic bacteria produce chemical products. We can manipulate genes coding for enzymes to catalyze synthesis of valuable chemicals. Phenylalanine used in aspartame sweetener can be grown by engineered bacteria. Transgenic bacteria process minerals.
Electric current makes tiny holes in a plasma membrane through which genetic material enters.
About fifty types of genetically engineered plants have entered field trials. Major crops that can be improved in this way are soybean, cotton, alfalfa, rice, potato, and corn. Plants can be engineered to produce human proteins, such as hormones, in their seeds. Mouse-eared cress has been engineered to produce a biodegradable plastic in cell granules. It is possible to microinject foreign genes into eggs by hand.