High yield production of cellulose by a Komagataeibacter rhaeticus PG2 strain isolated from pomegranate as a new host

Abstract

Gluconacetobacter xylinus is a well-known organism that produces bacterial cellulose (BC). The present study was undertaken to find an alternative bacteria from a collection of 216 bacterial isolates, which were isolated from different rotten fruits and fermented beverages, to find a better producer of bacterial cellulose. We obtained a potent strain, which produced a high yield of BC from a rotten pomegranate sample, and was further identified as Komagataeibacter rhaeticus strain PG2 using 16S rRNA gene sequence analysis. To date, only two strains of Komagataeibacter rhaeticus are known to produce BC, and these were mainly isolated from a fermented beverage, kombucha. For the first time, we have isolated a BC producing Komagataeibacter rhaeticus strain PG2 from a rotten pomegranate sample. The new host environment and the substrate utilization pattern of strain PG2 reveal efficient bacterial cellulose production. Hestrin–Schramm (HS) liquid media containing glycerol as a carbon source resulted in the highest BC production (∼6.9 g L⁻¹). A further increased yield of BC (∼8.7 g L⁻¹) was obtained by using 3% (w/v) glycerol concentration, and this BC yield is the highest reported among any of the known Komagataeibacter rhaeticus strains reported. A detailed physico-chemical characterization of the BC membrane obtained from glycerol (Gly-BC) and glucose (Glc-BC) was performed. Interestingly, Gly-BC is found to be more compact and more crystalline in its nature compared to Glc-BC. The present study reveals the isolation of an efficient BC synthesizing strain using glycerol as a low-cost carbon source, confirming the economic feasibility of BC production. The structural characteristics of the BC membrane produced by glycerol were found to be more suitable for various applications.