Types of good bacteria and bad bacteria and why they are good or bad?

Question

What are some examples of good and bad bacteria, why are those types of bacteria good or bad? [ex. Good bacteria-Rhizobium-free living nitrogen fixing species]

Answer 1

Bad bacteria cause diseases in human, animals and plants, and cause spoilage of our food. Good bacteria are those that are normal inhabitants of our guts, protecting us from harmful microorganisms, and those that recycle biomass, and those that help us preserve food, like the Lactobacillus (cheese, sauerkraut).

Answer 2

Probiotics like Enterococcus, Bifidobacterium, Lactobacillus are "good bacteria".
Bad ones are pathogens like Clostridium difficile (diarrhea in children), enterotoxigenic and enteropathogenic E coli.

Those are inside us. Good ones in general are our natural microflora found everywhere inside out (their number is many times more than our body cells put together). Some of these flora are good in the sense that they produce acidic pH which makes it inhospitable for pathogenic ones. They colonize us so that the pathogenic ones can't.

Of these, there're opportunistic pathogens which when the flora is disturbed (antibiotic treatment) or they're able to enter (cuts etc.), they can multiply and be bad.

Most bacteria (fungi and yeast) used in the industry are good in that they gives flavor and adds value (via secondary metabolites).

Acinetobacter for example cleans up hydrocarbon pollutants.

In the lab, both "good" and "bad" are treated BAD and aseptic techniques are practised at all times.