How is Turbidity related with number of microbes in a coloured sample of water?

Question

(Note that colour also affects turbidity, so if we say that increase in microbial content increase the turbidity,that's not true because in some cases there are no microbes still the turbidity levels are high because of colour with reflects the light passing through sample and increases turbidity)

Answer 1

Fluids can contain suspended solid matter consisting of particles of many different sizes. While some suspended material will be large enough and heavy enough to settle rapidly to the bottom container if a liquid sample is left to stand (the settleable solids), very small particles will settle only very slowly or not at all if the sample is regularly agitated or the particles are colloidal. These small solid particles cause the liquid to appear turbid. Therefore, the more cells that are present in a clear liquid medium, the more turbid the medium will appear.

Answer 2

True, microbes can have absolutely nothing to do with turbidity because in natural settings, the majority of turbidity is from sediment contamination (dirt, soil).  

I'm not quite sure what you're asking, but increased turbitidy blocks the passage of light, the reason why perpetual muddy water often has no aquatic plant life...no sunlight.  Colored dyes do the same thing, that's why you see some ponds where the water has been dyed the aqua blue color, to block the sunlight and reduce unwanted plant growth.

As far as microbes go, low pH, acid mine runoff (water) is crystal clear because there is no life in it; microbial, plant or animal.