Investigating the Combined Effect of Trehalose, Oxyanions and their Counter Ions On The Survivability of the Lactobacillus acidophilus Bacteria

Lactobacillus acidophilus is a bacterium commonly found in milk and other dairy products. It is particularly renowned for its function as an aid for digestion in the gastrointestinal tracts of humans, and is the primary means through which vitamin K (a vital cofactor for blood clotting) is synthesized in the intestines. Its value has influenced its use in industry as an additive in almost all dairy products today. However, concerns have been raised about the duration of its lifespan after undergoing the rigorous but indispensable process of freeze-drying (a preservation technique for biological samples) before being included in various diary products. The purpose of this research is to investigate how the combination of trehalose (a naturally occurring disaccharide of glucose) and various salts may help the bacteria retain its cell structure, maintain the cell integrity, and ultimately increase its survivability after freeze-drying. Determining the effect of the trehalose and salt compounds on the bacteria was done in two ways:  measuring the glass transition temperature of the bacteria/salt/sugar complex using a differential scanning calorimeter (DSC) and calculating the recovery of the bacteria after rapid freezing and thawing. A high glass transition temperature and recovery rate of the bacteria would indicate a good result. Preliminary experiments suggests that a 20% trehalose solution added in equimolar amounts to a sodium phosphate monobasic salt and bacteria cell concentrate might yield the best result after freeze-drying.