Types of Growth
Growth of microorganisms may be:
Antagonistic
Synergistic
Symbiotic
Growth is antagonistic when the growth of one microorganism produces a product that is harmful to another. An example is when a microorganism produces bacteriocins. Other microorganisms are killed.
Growth is synergistic when microorganisms can grow separately, but they grow better in mixed culture. An example of this is the growth of Streptococcus thermophilus and Lactobacillus delbrueckii subspp bulgaricus in milk. Separately, each can product 8 10 ppm of acetaldehyde. However, when growing together, they can produce 30 ppm of acetaldehyde.
Growth is symbiotic when one where two or more microorganism must grow together, each producing something that another needs. An example of this is also seen in the growth of Streptococcus thermophilus and Lactobacillus delbrueckii subspp bulgaricus in milk. S. themophilus produces amino acids needed by L. delbrueckii; L. delbrueckii produces formate needed by S. themophilus.