Final answer:
In bacteria, the helicase enzyme is responsible for separating DNA strands by breaking hydrogen bonds. DNA gyrase relaxes supercoiling, and DNA ligase seals nicks in the DNA, but neither break hydrogen bonds between DNA strands.
Step-by-step explanation:
The enzyme in bacteria that disrupts hydrogen bonds connecting the two DNA strands is known as helicase. This enzyme is responsible for unwinding the DNA at the origin of replication by breaking the hydrogen bonds between the nitrogenous base pairs, allowing the DNA to be 'read' and for replication to occur. Although other enzymes like gyrase, ligase, DnaA, DnaB, and DnaG play significant roles in DNA replication and other cellular processes, it is helicase that directly deals with the separation of DNA strands.
It's important to note that DNA gyrase is a type of topoisomerase that relaxes supercoiling of the DNA, making it more accessible for processes such as replication; however, it does not break hydrogen bonds between the strands. Similarly, DNA ligase seals nicks in the sugar-phosphate backbone of DNA molecules but does not separate DNA strands. The other enzymes mentioned, DnaA, DnaB, and DnaG, are also involved in the initiation and elongation stages of DNA replication, but do not break hydrogen bonds between DNA strands.