Chlorophyll stability of epilithic cyanobacteria from temples of India

Abstract

The cyanobacterial cells inhabiting the crust of Sun temple, Konark react to TTC by forming reddish formazan crystals for SH groups. Pretreatment with up to 5 M urea, 1% hydrogen peroxide or heating the crust in dry state at 60 °C up to 1 hour had no effect on TTC reduction. Keeping the crusts in desiccated state up to 4 months also did not reduce their TTC reduction activity, whereas exposing to heat by keeping in a waterbath (wet state) even for 10 minutes rendered the cyanobacterial cells inactive. All these tests indicate that TTC reduction is due to presence of SH groups in epilithic cyanobacterial cells exposed to bright sunlight. The cyanobacterial component of the tuft of Kedar-Gouri temple also reduced TTC. But the activity was lost after pretreatment with heat (60 °C) in wet or dry state, upon exposure to H 2 O 2 , urea and also when kept in a desiccator for a prolonged period. This showed that the cyanobacterium Tolypothrix byssoidea inhabiting the crust of Sun temple, Konark was comparatively more tolerant to adverse conditions than that of the epilithic tuft of Kedar-Gouri temple containing T. scytonemoides. Chlorophyll a, carotenoid and scytonemin pigment content of the cells of both the organisms was reduced on heat treatment in wet state was more detrimental for pigment synthesis than the heat treatment in dry state. Chlorophyll stability index showed that the tufts containing T. scytonemoides was more susceptible to heat injury than that of T. byssoidea which occur as crust on the temple walls.