USE OF ACTIVATED-CHARCOAL FOR THE PRESERVATION OF ANAEROBIC PHOTOTROPHIC AND OTHER SENSITIVE BACTERIA BY FREEZE-DRYING

Lyophilization of anaerobes and anaerobically grown cultures of anoxygenic phototrophic bacteria is difficult as it is essential to maintain anaerobic conditions and to avoid the exposure of phototrophic cultures to ligt during freeze-drying process. During a systematic investigation, it was observed that activated charcoal protected phototrophically grown cultures against photooxidation by absorbing light and O before freeze-drying. Using activated charcoal (5% w/v) in suspending media along with skim milk (20% w/v) and raffinose (5% w.v) or mose-inositol (5% w/v) as protective agents several anaerobic purple nonsulfur bacteria, Chromatiaceae, Ectothiorhodosporaceae and green sulfur bacteria were successfully preserved. Several other bacteria, such as Camplyobacter, Spirillum, Hydrogenophaga, Vibrios and Zymophilus which are sensitive to aerobic freeze-drying, also survived with a good percentage survival recovery after freeze-drying under these conditions. The use of activated charcoal as an adsorbent of harmful radicals in suspending media for the reactivation of lyophilized anaerobes is also recommended. © 1990.