The predominant colonic bacteria are -

Ans. is 'b' i.e., Largely anaerobic " The greatest number of bacteria found in colon are bacteriods, a group of gram- negative, anaerobic, non-spore forming bacteria. "-------Todar s 68o Anaerobic bacterias exist as components of the normal flora on the mucosal surfaces of humans and animals,o The major reservoirs of these bacteria are the mouth, lower gastrointestinal tract, skin and female genital tract.Oral cavityo Among the constituents of the oral flora, anaerobes are the predominant organisms, ranging in concentration from l09ml in saliva to 1012/ml in gingival scrapings.o In the oral cavity, the ratio of anaerobic to aerobic bacteria ranges from 1:1 on the surface of tooth to 1000:1 on the gingival crevices.Gastrointestinal tracto Anaerobic bacteria are not found in appreciable numbers in the normal upper intestine until the distal ileum,o In the colon, the proportion of anaerobes increases significantly as does the overall bacterial count,o For example in colon there are I011 to 1012 organism per gram of stool with an anerobe to aerobe ratio of 1000:1. Female genital tracto In the female genital, there are ~ 10* organisms per millilitre of secretions with anaerobe to aerobe ratio ~ 10:1.