Microorganisms such as bacteria, true fungi, and unicellular algae, are one of useful marine resources. We have so far searched and isolated unique and useful microorganisms in marine environments. We have investigated biochemical, physiological, and ecological properties of these microorganisms to produce chemicals and bioenergy. In addition, it is imperative to control harmful microorganisms such as food-poisoning bacteria in food-manufacturing factories. We have also investigated the optimization of cleaning and disinfecting operations of food-processing equipment from interfacial aspects.