Almost all microorganisms in natural and technical environments are exposed to fluctuations in the external conditions. How they cope with such fluctuations, and continue to grow and survive after environmental conditions have changed, is a important question. We developed new experimental approaches to follow individual bacterial cells over time and across changes in the environmental conditions, both in laboratory settings and in natural aquatic environments. These experiments help identify bacterial strategies in fluctuating environments: We find that nutrient limitation induces metabolic diversity between individual cells, and thereby allow groups of bacteria to cope with changes in the nutrient composition. And we find that individual bacterial cells form a cellular memory of conditions they encountered in the past, and thereby can better cope with recurrent exposure to environmental.