Sago as a medium for “in vitro” culture of some common soil bacteria

Abstract

Nutrient agar (NA) medium is universally used as a general purpose medium for the culture of a broad range of bacteria and the cost of this commercially available medium is considerably high. Sago (Metraxylon sagu) contains a considerable amount of starch and a small amount of reducing sugars and is not used as a staple food in Sri Lanka. This study was aimed to find out the suitable composition of the sago medium compared with NA and to carry out growth studies of soil bacteria on sago medium. Media were prepared in different compositions by addition of different amount of sago in 100mL volume (25mL of distilled water + 75mL of young king coconut sap) separately. Bacterial suspensions (5.21×106 cfu/ml, SD=1.12) of Bacillus, Pseudomonas, Klebsiella, Enterobacter, Serratia and Staphylococcus were transferred on the selected sago medium separately by using spread plate techniques. There was no significant difference between sago and NA media in number of the colonies (t test; p = 0.05). Colonies appeared earlier in NA media than in sago media. But the colony morphological characters such as shape/form, margin, elevation, colour and size were almost similar to all bacteria selected on both media, except consistency. Thus, instead of NA the low cost and easily available sago medium could be recommended for the cultivation of soil bacteria.