The bacteria which are associated with ethanoic acid production in beer are grouped together and called acetic acid bacteria. Two common examples are Acetomonas and Acetobacter. The latter is discriminated from the former by motility through the use of peritricous flagellation (I tried that once but didn’t like it). The most important thing about acetic acid bacteria in terms of brewing is that they are obligate aerobes which means they cannot grow in the absence of oxygen. Yeast use up all the oxygen in beer at the first stage of fermentation so unless you have the misfortune to buy beer from a pub where they serve you beer from casks which have been left open for 7 days, you are unlikely to find them problematic.
Ethanoic has a sour smell and sour sharp taste. The characteristic sourness of Lambics is principally due to a combination of ethanoic and lactic acids although a number of other organic acids are involved.