The agar should be an enriched medium that will support the growth of common "contaminating" organisms.

Blood agar is an enriched medium in which nutritionally rich whole blood supplements the basic nutrients.

Since gamma-tocopherol is depleted from macrophages more rapidly than alpha-tocopherol the time interval between removal of the tocopherol enriched medium and cell harvesting could be an important variable.

This involves growing the samples in an enriched medium to improve the viability of the GBS in the same as opposed to the other naturally occurring bacteria.

In Microbiological laboratories, B. anserina bacteria can be grown on special protein enriched mediums (rich in ovoalbumins or animal tissue (that contains Myoglobin)), in anaerobic conditions.