Trehalose

Pseudarthrobacter sp. TBRC 2005 was provided by the Thailand Bioresource Research Center (TBRC) (www.tbrcnetwork.org). The bacterial strain was cultivated at 30 °C in nutrient broth for genomic DNA extraction. Escherichia coli DH5α was used as a host for plasmid propagation and E. coli BL21(DE3) (Invitrogen, Carlsbad, CA, USA) was used for recombinant protein production. The pJET1.2 vector and pET28a vectors (Novagen, Darmstadt, Germany) were used for cloning and protein expression, respectively. Maltose and trehalose used as standardss for analysis were purchased from Megazyme (Wicklow, Ireland). All analytical-grade chemicals and reagents used in this work were purchased from Sigma-Aldrich, Merck and Fluka.

Thin-layer chromatography mobile phase was composed of butanol:acetic acid:distilled water (2:1:1). Standard solutions of glucose (0.4 mg/mL), sucrose (0.5 mg/mL), trehalose (0.5 mg/mL) (Megazyme, Wicklow, Ireland) and the six samples (cultivars) were spotted on the Silica Gel 60 G F254 HPTLC plate (Merck, Darmstadt, Germany). The plate was allowed to develop for 2 h. The plate was dried and stained with 0.3% (w/v) Naphthol (Merck, Germany) in 95% (v/v) ethanol using sulfuric acid (Merck, Darmstadt, Germany) then heated with a hairdryer until all bands were visible.