Table 2 Change of microbial metabolites at different growing phases

Lag phase

Individual growth

Anabolic metabolism dominates in cell, extracellular enzyme synthesis and transshipment, substrate begin to degrade

Enzymes

Logarithmic phase

Individual reproduction, population growth increasing geometrically

All kinds of metabolism are very high

Enzymes, functional polysaccharide, polypeptides, etc. Primary metabolites, such as alcohol, amino acid, pyruvate, and citric acid

Stationary phase

Population growth and the rate equal to the death

Accumulation of metabolites begins the secondary metabolism

Secondary metabolites, such as antibiotics, hormones, toxins, and pigments

Decline phase

Growth is inhibited by substrate, and the cells begin to autophagy

Old cell degradation, and new microbe population begins the new metabolism

Nucleotide, spore, sulfide, amino, monosaccharide, secondary metabolites