The maximum type of nutritional diversity is found in
Monera
Monerans have the maximum nutritional diversity as some of them are - autotrophs - can prepare their own food (eg. Cyanobacteria), heterotrophs - depend on others for food (eg. Escherichia coli), saprophytes - feed on dead and decaying matter, parasitic - live on other host cells for survival and cause, symbiotic - in mutual relation with other organisms (eg. Anabaena ), commensalism - it is where one organism is benefited and the other is not affected (eg. Salmonella), mutualism - where both the organisms are benefited.