A coupled fermentation system of Agrobacterium sp. ATCC 31749 and Trichoderma harzianum GIM 3.442 (AT-CFS) with wheat bran as the optimal nitrogen source was established for producing low-molecular-weight curdlan with high production, which can potentially reduce the cost of low-molecular-weight curdlan biosynthesis. The initial inoculate ratio, pH and the fermentation time were optimized. Compared with the curdlan from the single fermentation system of Agrobacterium sp. ATCC 31749 (A-SFS), the molecular weight (Mw) of the curdlan produced from AT-CFS decreased by 34.01% (from 110.85kDa to 73.15kDa), and the curdlan production (47.9g/L) and conversion rate of glucose to curdlan (0.60g/g) increased by 119.93% and 36.36%, respectively. The results of RT-PCR showed high curdlan production in AT-CFS was highly correlated with aerobic respiration intensity and curdlan synthase activity. The structure of the curdlan from AT-CFS was the same as that from A-SFS.

molecular weight, Curdlan, coupled fermentation system

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6
	bDGlcp	103.53	76.83	86.65	68.89	73.36	61.35


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6
	bDGlcp	4.52	3.26	3.44	3.26	3.26	3.44-3.68


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6
	bDGlcp	103.53/4.52	76.83/3.26	86.65/3.44	68.89/3.26	73.36/3.26	61.35/3.44-3.68

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

*O[C@@H]1[C@@H](O)[C@H](*)O[C@H](CO)[C@H]1O

162.141 g/mol (C₆H₁₀R₂O₅, R = next and previous repeats, not counted in mol weight)