Cold adaptation of the Antarctic haloarchaea Halohasta litchfieldiae and Halorubrum lacusprofundi

Abstract

Halohasta litchfieldiae represents ∼ 44% and Halorubrum lacusprofundi ∼ 10% of the hypersaline, perennially cold (≥ -20°C) Deep Lake community in Antarctica. We used proteomics and microscopy to define physiological responses of these haloarchaea to growth at high (30°C) and low (10 and 4°C) temperatures. The proteomic data indicate that both species responded to low temperature by modifying their cell envelope including protein N-glycosylation, maintaining osmotic balance and translation initiation, and modifying RNA turnover and tRNA modification. Distinctions between the two species included DNA protection and repair strategies (e.g. roles of UspA and Rad50), and metabolism of glycerol and pyruvate. For Hrr. lacusprofundi, low temperature led to the formation of polyhydroxyalkanoate-like granules, with granule formation occurring by an unknown mechanism. Hrr. lacusprofundi also formed biofilms and synthesized high levels of Hsp20 chaperones. Hht. litchfieldiae was characterized by an active CRISPR system, and elevated levels of the core gene expression machinery, which contrasted markedly to the decreased levels of Hrr. lacusprofundi. These findings greatly expand the understanding of cellular mechanisms of cold adaptation in psychrophilic archaea, and provide insight into how Hht. litchfieldiae gains dominance in Deep Lake.

Denitrifying haloarchaea within the genus Haloferax display divergent respiratory phenotypes, with implications for their release of nitrogenous gases

“…Haloarchaea live and proliferate in extreme environments, characterized by salt concentrations up to saturation, high temperatures (although, some are cold adapted; Dassarma et al, ; Williams et al, ), high solar radiation and high ionic strength (Oren, 2013a; ; ). Under these conditions, oxygen availability is low (Oren 2013a).…”

Current developments on polyhydroxyalkanoates synthesis by using halophiles as a promising cell factory

“…mediterranei PhaC was identified in Hrr. lacusprofundi [38]. Interestingly, this haloarchaeon is known to produce PHA at low temperatures as higher abundances of PhaC proteins were observed at low temperatures.…”

“…[34][35][36][37]. In 2017, it was reported that Halorubrum lacusprofundi, the third most abundant species in the Deep Lake community of Antarctica, produced PHA-like granules at low temperature [38]. To date, haloarchaeal species belonging to almost 17 genera have been reported to exhibit PHA-accumulating ability (Table 1).…”

“…Haloarcula Haloarcula marismortui [27] Haloarcula hispanica [28] Haloarcula vallismortis [29,30] Haloarcula japonica [30] Haloarcula amylolytica [35] Haloarcula argentinensis [35] Haloferax Haloferax mediterranei [28] Haloferax volcanii [28] Haloferax gibbonsii [28] Halopiger Halopiger aswanensi [31,32] Haloquadratum Haloquadratum walsbyi [33] Halobacterium Halobacterium noricense [36] Halobacterium cutirubrum [35] Halobacterium halobium [35] Halostagnicola Halostagnicola larsenii [35] Haloterrigena Haloterrigena hispanica [37] Haloterrigena turkmenica [35] Halobiforma Halobiforma nitratireducens [35] Halobiforma haloterrestris [34] Halococcus Halococcus morrhuae [35,36] Halococcus saccharolyticus [36] Halococcus salifodinae [36] Halococcus dombrowskii [36] Halococcus hamelinensis [36] Halococcus qingdaonensis [36] Halorubrum Halorubrum coriense [36] Halorubrum chaoviator [36] Halorubrum litoreum [35] Halorubrum trapanicum [35] Halorubrum lacusprofundi [38] Halalkalicoccus Halalkalicoccus tibetensis [35] Halogeometricum Halogeometricum borinquense [42] Halogranum Halogranum amylolyticum [46] Natrinema Natrinema altunense [35] Natrinema pallidum [35] Natrinema pellirubrum [35] Natrinema ajinwuensis…”

“…Since, degradation of BCAA or its intermediate oxoacid precursor can generate propionyl-CoA, it was hypothesized that PHA accumulation was linked to the demand for BCAA in Hrr. lacusprofundi [38].…”