Deterioration of concrete structures, together with corrosion of reinforcing steel due to the action of microorganisms, is known as Microbiologically Induced Corrosion of Concrete (MICC). The activity of microorganisms can initiate and further accelerate both steel corrosion and cement-based matrix degradation in reinforced concrete structures. The mechanism is related to initial surface colonization and further bio-products (and aggressive substance respectively) penetration into the bulk concrete matrix, reaching the reinforcement level. Common knowledge is that bio-deterioration-related infrastructure degradation, maintenance and repair have a significant economic impact worldwide. However, due to the complexity of all related mechanisms, a durable and feasible solution is still to be achieved for the engineering practice. This paper briefly points out main bio-degradation related mechanisms for concrete, steel and reinforced concrete structures and presents results on the electrochemical response of carbon steel in simulated environment under biotic and abiotic conditions.