Question

Bacillus thuriniensis is an example of a bacteria used in agricultural applications. Why is this microbe used in these applications? It contains a Ti-plasmid that gives octopines to the plant. It liberates soil phosphorus to help the plant obtain phosphorus. It produces a compound called Bt-toxin that kills insect pests. It produces a potent antibiotic that fights off pathogenic microorganisms.

Answer 1

Answer-

Bacillus thuringiensis , is a Gram- positive , aerobic , endospore forming bacteria with ,motile flagella .

It contains ti plasmid that gives octopines to the plants , Ti plasmid contains T DNA which is transferred into the plant cell and undergoes random intigration with the plant cell Chromosome . Ti plasmid can contains multiple copies of the DNA . During infection multiple copies of T DNA are intigrated onto the plant chromosome . It has various components like opines and agropines , plants cannot metabolise opines like as ocpopines and agropines because of does not have any catabolic enzyme against opines and agropines

It is a common soil bacterium that is employed for the control of the caterpillar .

The bacterium forms a solid and toxic protein crystal known as parasporal body, next to their spores at the time of endospore forming . The parasporal body contains protein toxins .

Cultures of sporulated bacteria are dried and dusted onto crop plants but when ingested by gypsy moth larvae, cabbage worms and several others ,the parasporal body is fragmented into protoxin subunits by the alkaline gut contnents.

Protoxin is converted into active toxin which causes an influx of water and cations as well as loss of ATP and finally cel lysis occur .

Death occurs within 30 minutes to 3 days after ingestion of the bacterium .

Fir the preperation of Bt toxin , B. thuringiensis is grown in fermentors , when the lysis of bacterial cell occurs , the endospores and toxic protein crystals are released into the broth medium . The medium is then centrifuged and made up as a dust or wettable powdry to be used as a spray on the agricultural . Example the leaves of transgenic cotton plants , produced through cell cultures , secrete the lethal toxins . When the bollworm eats upon cotton leaves toxin is taken up by them .

Toxin is activated in their guts which is resulting in the death of bollworm.