Question

Bt gene occurs in
a. Bacillus thuringiensis
b. Escherichia coli
c. Agrobacterium tumefaciens
d. Rhizobium leguminosarum

Answer 1

Bt is gram-positive bacteria that is commonly used as a biological pesticide. The crystal proteins are produced by the Bt strains during the process of sporulation. It is used in the soil-dwelling bacteria which produces toxin naturally and it is commonly used in organic farming.

Complete answer:

Bt gene occurs in Bacillus thuringiensis which forms spores in the insecticidal bacteria. Bt gene will become active at high pH and release a toxin in the gut of the insects. Since the 1950s, it is a naturally occurring bacteria which is a soil-borne and natural insect controller. Various insecticidal proteins are synthesized by the Bt bacteria named Cry, Vip, and Cyt. They have the capability to kill nematodes or insect orders.

The bacteria which lives normally in your intestines are called Escherichia coli (E. coli). They do not harm the body and even keep the digestive tract healthy. Not only in the human intestines, but E. coli strains are also found in the environment and food. The group of this bacteria is large and diverse. Some strains of E. coli can cause diarrhea, infections in the urinary tract, pneumonia, etc.

The causal agent of crown gall disease is Agrobacterium tumefaciens. It is a gram-negative soil-borne bacterium that is rod-shaped. It is used in the genetic engineering process. It also helps in the process of transformation in which a small DNA segment is used and transferred into the plant genome.

The bacteria which survive and reproduce in the soil as well as fix atmospheric nitrogen are called Rhizobium leguminosarum.

Hence, the correct answer is option (A).

Note: Bacillus thuringiensis (Bt) is the bacterial gene that is highly active and used in various growing methods like Bt cotton. The crystal proteins produced by the Bt gene are used to control insect practices in agriculture like sprays or it will be expressed in genetically modified plants. Bt cotton is a genetically modified plant.