TABLE 4.

Effects of disaccharide osmoprotectants on the osmolyte compositions of salt-stressed cultures of S. meliloti 102F34

Disac-charide addeda	Amount of accumulated osmolytes (nmol mg of protein−1) in cells at:
	Early exponential phaseb			Late exponential phaseb
	Glutamate	NAGGN	Trehalose	Glutamate	NAGGNc	Trehalosec
None	650	150	50	510	510	150
Sucrose	700	190	65	1,160	670	130
Trehalose	710	180	55	1,190	650	130
Maltose	690	190	60	1,220	690	130
Cellobiose	710	180	55	1,170	620	130

^aCultures were grown in LAS with 0.5 M NaCl plus the indicated disaccharide (1 mM). 

^bThe patterns of glutamate, NAGGN, and trehalose accumulation during the growth cycles of stressed cultures grown with trehalose, maltose, or cellobiose were very similar to those observed during growth of stressed cells cultured in the presence of either sucrose (20) or ectoine (56). Osmolyte levels in cells at early and late exponential phase of growth were determined after 5 to 8 h and 24 to 30 h of culture (corresponding to their maximal level), respectively. Data are means of triplicate assays with less than 10% standard deviations. 

^cSimilar levels of NAGGN and trehalose were found in cells at stationary phase, while glutamate contents were lower.