Green Sulfur Bacteria

The green sulfur bacteria are also called the Chlorobi or the Chlorobiaceae, which essentially means the green ones.  They are anaerobes, meaning that they do not grow in the presence of oxygen gas, and most are autotrophs.  Most also require reduced sulfur compounds like sulfide (the potent smell in rotting eggs and in salt marshes at low tide) to grow. Typically, they are found low down in Winogradsky columns where sulfide concentrations are high and there is no oxygen.  In nature they are found in areas where there is light, low oxygen and sulfide: volcanic hot springs, salt marsh sediments, and deep in freshwater lakes.

To isolate green sulfur bacteria from a Winogradsky column, a syringe is used to collect material from green or brown patches low in the column.  This material is then transferred to a growth medium that contains sulfide, no oxygen and very simple carbon sources.  These tubes are then put in dim light.  When the tubes turn green or brown, they are transferred to a fresh tube of the same medium to see if they will grow well in the laboratory.

We have isolated several strains of green sulfur bacteria in the lab from Winogradsky columns started from salt marsh sediments along Canary Creek in Lewes, Delaware.

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