Cultivable bacteria from ancient algal mats from the McMurdo Dry Valleys, Antarctica

Abstract

The McMurdo Dry Valleys in Antarctica are a favorable location for preservation of dormant microbes due to their persistent cold and dry climate. In this study, we examined cultivable bacteria in a series of algal mat samples ranging from 8 to 26539 years old. Cultivable bacteria were found in all samples except one (12303 years old), but abundance and diversity of cultivable bacteria decreased with increasing sample age. Only members of the Actinobacteria, Bacteroidetes, and Firmicutes were found in the ancient samples, whereas bacteria in the 8-year-old sample also included Cyanobacteria, Proteobacteria, and Deinococcus-Thermus. Isolates of the Gram-positive spore-forming bacterium Sporosarcina were found in 5 of 8 samples. The growth of these isolates at different temperatures was related to the phylogenetic distance among genotypes measured by BOX-PCR. These findings suggest that adaptation to growth at different temperatures had occurred among Sporosarcina genotypes in the Dry Valleys, causing the existence of physiologically distinct but closely related genotypes. Additionally, fully psychrophilic isolates (that grew at 15°C, but not 25°C) were found in ancient samples, but not in the modern sample. The preservation of viable bacteria in the Dry Valleys could potentially represent a legacy of bacteria that impacts on current microbial communities of this environment.

Local and regional influences over soil microbial metacommunities in the Transantarctic Mountains

“…For soil microbial communities worldwide, .80% of the cells and ;50% of species are dormant (Lennon and Jones 2011), and nutrient poor habitats tend to have larger proportions of dormant cells (Jones and Lennon 2010). The presence of such a cryptobiotic seed bank has been demonstrated for MDV soils , Antibus et al 2012, Tiao et al 2012. Diversity patterns observed in this study for total bacteria (i.e., [SjE] only significant over broad spatial scales in Table 4, shallower slope than cyanobacteria in Fig.…”

Key microbial drivers in Antarctic aquatic environments

“…Certain groups are regularly detected in Antarctic mats: Cyanobacteria, particularly members of the Oscillatoriales such as Leptolyngbya and Phormidium, and the Nostocales (Taton et al, 2003;Jungblut et al, 2005;Taton et al, 2006;Fernández-Valiente et al, 2007;Sutherland, 2009;Borghini et al, 2010;Verleyen et al, 2010;Anderson et al, 2011;Callejas et al, 2011;Fernandez-Carazo et al, 2011), Proteobacteria, the CFB group, Actinobacteria, and Firmicutes (Brambilla et al, 2001;Van Trappen et al, 2002;Peeters et al, 2011;Antibus et al, 2012a;Varin et al, 2012). Less commonly reported are Deinococcus-Thermus, Planctomycetes, Verrucomicrobiales, and others (Brambilla et al, 2001;Antibus et al, 2012b;Peeters et al, 2012;Varin et al, 2012). Diatoms may be absent , present at low levels alongside dominant Cyanobacteria (Sutherland, 2009;Hawes et al, 2011), or in some cases present as the dominant phototrophs (Fernández-Valiente et al, 2007).…”

Diversity of extremophilic bacteria in the sediment of high-altitude lakes located in the mountain desert of Ojos del Salado volcano, Dry-Andes

“…These lakes might be inhabited by several hitherto unknown microorganisms with special adaptive strategies to the extreme environmental conditions (Ordoñez et al 2009). Former studies focused mainly on other lakes of the Dry-Andes (Demergasso et al 2008;Dorador et al 2008Dorador et al , 2013Cabrol et al 2009;Farías et al 2009Farías et al , 2014Lynch et al 2012;Scott et al 2015), and research was also performed on similar environments, for example Antarctic lakes and permafrost (Goordial et al 2016;Aislabie et al 2013;Antibus et al 2012;Cowan et al 2002) and high-altitude lakes or permafrost of the Tibetan Plateau (Wu et al 2006;Xing et al 2009;Zhang et al 2007). Understanding the microbial processes in degrading permafrost is also an important issue, since thawing is proven to cause shifts in microbial communities, functional gene abundances which might be responsible for changes in global carbon cycle (Mackelprang et al 2011;Tas et al 2014;Hultman et al 2015).…”