Physiological and gene expression responses to nitrogen regimes and temperatures in Mastigocladus sp strain CHP1, a predominant thermotolerant cyanobacterium of hot springs

• Cyanobacteria are widely distributed primary producers with significant implications for the global biogeochemical cycles of carbon and nitrogen. Diazotrophic cyanobacteria of subsection V (Order Stigonematales) are particularly ubiquitous in photoautotrophic microbial mats of hot springs. The Stigonematal cyanobacterium strain CHPI isolated from the Porcelana hot spring (Chile) was one of the major contributors of the new nitrogen through nitrogen fixation. Further morphological and genetic characterization verified that the strain CHP1 belongs to Stigonematales, and it formed a separate Glade together with other thermophiles of the genera Fischerella and Mastigocladus. Strain CHP1 fixed maximum N-2 in the light, independent of the temperature range. At 50 degrees C niJH gene transcripts showed high expression during the light period, whereas the nifH gene expression at 45 degrees C was arrhythmic. The strain displayed a high affinity for nitrate and a low tolerance for high ammonium concentrations, whereas the narB and glnA genes showed higher expression in light and at the beginning of the dark phase. It is proposed that Mastigocladus sp. strain CHPI would represent a good model for the study of subsection V thermophilic cyanobacteria, and for understanding the adaptations of these photoautotrophic organisms inhabiting microbial mats in hot springs globally.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Miljöbioteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Environmental Biotechnology (hsv//eng)

NATURVETENSKAP  -- Biologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences (hsv//eng)

Nyckelord

Gene expression

Mastigocladus sp.

Nitrate/ammonium preference

Thermotolerance

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)