Which of the following are likely to be present in deep-sea hydrothermal vents?

In $Aulosira$,$Tolypothrix$ and $Nostoc$, . . . . . . are the sites for Nitrogen fixation.

Which of the following is called the "Jokers of the microbiological park"?

$......$ bacteria oxidise various inorganic substances such as nitrites,ammonia and use the released energy for $\text{ATP}$ production $:-$

$A$ Dutch scientist $A.V.$ Leeuwenhoek discovered bacteria for the first time in:

The structure present in cyanobacteria $(BGA)$ that helps in nitrogen fixation is