Table 1.

The PSE (chlorophyll red edge for Chroococcidiopsis) for given organisms mixed with sand compared to pure colonies and quartz sand controls (figure 3). PSE was calculated as (r_b−r_a)/r_a, where r_b was the mean reflectance from 740 to 800 nm for all organisms, and r_a was the mean reflectance from 420 to 480 nm for C. metallidurans and D. radiodurans and 600–670 nm for Chroococcidiopsis. See text for details.

	Cupriavidus metallidurans	Deinococcus radiodurans	Chroococcidiopsis
quartz sand control	0.33	0.32	0.06
bacterial colonies	−0.02	4.13	21.4
bacteria and sand	0.32a	0.28a	0.12b; 0.07c

^a10⁸ organisms cm⁻³.

^b10⁶ organisms cm⁻³.

^c2×10⁵ organisms cm⁻³.