What is the name of the bacterial enzyme that synthesizes new DNA strands?

DNA polymerase is the bacterial enzyme that synthesizes new DNA strands.

During replication, DNA polymerase reads the bases on an existing template strand and adds matching deoxyribonucleotides to the growing strand. It extends the new strand at its 3′ end, so synthesis proceeds in the 5′-to-3′ direction. Because it needs an existing 3′-hydroxyl group, another enzyme first helps create a short RNA primer.

Bacterial DNA replication involves several specialized proteins. Helicase separates the two DNA strands, while ligase seals breaks between DNA fragments, especially on the lagging strand. DNA polymerase performs the central nucleotide-adding job, although different bacterial polymerases can have distinct roles in replication, repair, and proofreading.

Some DNA polymerases can detect and remove incorrectly inserted bases through proofreading, greatly improving copying accuracy. A frequent misconception is that DNA polymerase starts a strand from nothing; it generally cannot do that and must extend a primer. RNA polymerase is different because it synthesizes RNA rather than DNA.