TABLE 2.

Effects of pH and temperature on lipid composition

Growth conditiona	% (by wt) of lipid type detectedb			% (by wt) of lipids withc:		Avg no. of cyclopentane ringsd
	Phospholipid	Glycophospholipid	Glycolipid	0-1 sugar unit	2-4 sugar units
pH
3.0	NDe	85.3	14.7	86.0	14.0	5.1
2.4	NDe	85.9	14.1	83.9	16.1	4.8
1.8	2.6	75.9	21.5	78.7	21.3	4.1
1.2	1.0	53.6	45.4	64.4	35.6	4.0
Temp (°C)
45	2.8	76.9	20.3	83.8	16.2	3.6
50	2.9	78.8	18.4	80.8	19.2	3.9
55	2.6	75.9	21.5	78.7	21.3	4.1
60	4.5	64.1	31.4	77.9	22.1	4.5

^aThe upper section (pH) shows the effects of different pHs of the culture medium at 55°C, and the lower section (Temp) shows the effects of different growth temperatures at pH 1.8.

^bThe polar lipids were divided into three lipid types, phospholipid, glycophospholipid, and glycolipid. Data show weighted percentages of the three types with respect to the total weight of polar lipids, calculated from the data shown in Table 1.

^cValues show weighted percentages of polar lipids with sugar chain lengths of 0 to 1 and 2 to 4.

^dThe average number of cyclopentane rings in caldarchaeol was calculated as follows: (Area% monocyclic + 2 × area% bicyclic + 3 × area% tricyclic + 4 × area% tetracyclic + 5 × area% pentacyclic + 6 × area% hexacyclic) × 10⁻². Area% was estimated from the HPLC peaks shown in Fig. 2. Values were determined from three experiments.

^eND, as in Table 1, ND values were assumed to be zero, indicating that all the corresponding data in Table 1 are ND.