Esterase as an enzymatic signature ofGeodermatophilaceaeadaptability to Sahara desert stones and monuments

Abstract

Aim: To assess esterase profiling of members of Geodermatophilaceae isolated from desert stones and monuments in Tunisia and Egypt. Methods and Results: Members of Geodermatophilaceae family isolated from desert stones and monuments in Tunisia and Egypt were characterized by partial 16S rRNA sequences. Twenty‐five strains were clustered in three dissimilar groups of the genera Geodermatophilus (12 strains), Blastococcus (5 strains) and Modestobacter (3 strains). Isolates were also screened and typed based on major groups of esterase hydrolytic activity. Their esterase patterns were determined and compared to those of ten reference strains belonging to Geodermatophilaceae family. Strains exhibited a diverse and complex pattern of electrophoretic esterase bands, and 31 haplotypes were obtained for the 35 investigated strains. Esterases produced by members of Geodermatophilaceae family have an optimal activity around 40°C and at pH 8. Esterases from Geodermatophilus strains display a high resistance to thermal inactivation and alkaline pH and retaining 30 and 20% of activity after heating for 20 min at 120°C and at pH 12, respectively, and were completely inactivated after 30 min at 120°C. Enzyme activity has been strongly activated in the presence of Ca2+and Mg2+ ions and moderately by Zn2+ and was markedly inhibited by Cu2+ and Co2+ ions. Conclusions: Geodermatophilaceae isolates share a rich and particular pool of esterase activities that could be directly linked to harsh conditions characterizing their ecological habitat including high level of aridity, temperature, ionic strength and low nutrient availability. Significance and Impact of the Study: Esterase could be considered as enzymatic signature that outlines adaptability of Geodermatophilaceae in arid area.

Community Variability of Bacteria in Alpine Snow (Mont Blanc) Containing Saharan Dust Deposition and Their Snow Colonisation Potential

“…In addition, the Actinobacteria, namely those belonging to family Geodermatophilaceae, were found in almost all of our samples. They are predominantly recovered from extreme environments such as the Antarctic or hot desert soils (33), rocks and monument surfaces (12,13,34). Furthermore, some of the genera/phyla that have been identified in our dusty snow samples were also found previously in high mountain snow.…”

Diversity and Enzymatic Profiling of Halotolerant Micromycetes from Sebkha El Melah, a Saharan Salt Flat in Southern Tunisia

“…With regard to bacteria that have been well explored in southern desert region of Tunisia [28–31], data related to fungi are scarce and are limited to truffle and mycorrhiza, so far considered as real specialists of desert environments [32, 33]. To the best of our knowledge, this is the first report on the isolation and characterization of fungi from Tunisian desert and particularly from salt flat.…”

“…It has been postulated that microorganisms sharing a rich and particular extracellular enzymatic activities are common in harsh conditions characterizing their ecological habitat including high level of aridity, temperature, ionic strength, and particularly the low nutrient availability [31]. This implies the need by microorganisms for an effective utilization of each possible available organic compound [45].…”

Stone-dwelling actinobacteria Blastococcus saxobsidens, Modestobacter marinus and Geodermatophilus obscurus proteogenomes

“…These three genera have a complex life cycle and produce remarkably resistant enzymes such as esterases (Essoussi et al, 2010;Jaouani et al, 2012;Normand et al, 2014). They also have the ability to resist adverse environmental conditions such as ultraviolet light, ionizing radiation, desiccation and heavy metals (Rainey et al, 2005;Gtari et al, 2012;Montero-Calasanz et al, 2014, 2015.…”