I have 15 gallons of Niagara in strong primary fermentation (5th day) and
now I can detect a scent of vinegar, not overwhelming but appreciable.

I recall having this situation a couple of years ago. I applied a strong
SO2 after fermenetation completed and cold stabilized. The resulting wine
had no appreciable vinegar smell or taste.

Should I be concerned that the vinegar bacteria can make it's way over to my
other fermentation in the same room? If the vinegar odor does not subside
should I abandon pressing rather than infect my press?

thanks

Joe