A New Lineage of Halophilic, Wall-Less, Contractile Bacteria from a Brine-Filled Deep of the Red Sea

Abstract

A novel strictly anaerobic bacterium designated strain SSD-17BT was isolated from the hypersaline brinesediment interface of the Shaban Deep, Red Sea. Cells were pleomorphic but usually consisted of a central coccoid body with one or two "tentacle-like" protrusions. These protrusions actively alternated between a straight, relaxed form and a contracted, corkscrew-like one. A peptidoglycan layer was not detected by electron microscopy. The organism forms "fried-egg"-like colonies on MM-X medium. The organism is strictly anaerobic and halophilic and has an optimum temperature for growth of about 30 to 37°C and an optimum pH of about 7. Nitrate and nitrite are reduced; lactate is a fermentation product. The fatty acid profile is dominated by straight saturated and unsaturated chain compounds. Menaquinone 4 is the major respiratory quinone. Phylogenetic analysis demonstrated strain SSD-17B T represents a novel and distinct lineage within the radiation of the domain Bacteria. The branching position of strain SSD-17BT was equidistant to the taxa considered to be representative lineages of the phyla Firmicutes and Tenericutes (with its sole class Mollicutes). The phenotypic and phylogenetic data clearly show the distinctiveness of this unusual bacterium, and we therefore propose that strain SSD-17BT ‫؍(‬ DSM 18853 ‫؍‬ JCM 14575) represents a new genus and a new species, for which we recommend the name Haloplasma contractile gen. nov., sp. nov. We are also of the opinion that the organism represents a new order-level taxon, for which we propose the name Haloplasmatales.The divergent movement of the African and Arabian tectonic plates, which is associated with deposition of new oceanic crust, led to the formation of several isolated topographical depressions within the Red Sea basin (4). Redissolution of buried Miocenic evaporites and/or hydrothermal phase separation, followed by upward migration to the seafloor and later accumulation in enclosed depressions, filled as many as 25 such deeps with highly saline water (13,15). In addition to their common extreme salinity (up to 27% [wt/vol] NaCl), all of these brines are anoxic, are enriched in metals and hydrocarbons, and have temperatures higher than 21.7°C, which is the mean deep-seawater temperature of the Red Sea (13, 29).The brine-filled deeps of the Red Sea represent a rare type of extreme environment and were considered to be sterile as recently as the late 1960s (34). Few studies have focused on the microbiology of these biotopes, resulting in only a few microbial isolates (1, 2, 10). Phylogenetic studies have, however, revealed an unexpectedly high microbial diversity (10, 11). Parallel studies, focusing on the microbiology of analogous deep-sea brines located in the eastern Mediterranean Sea further corroborate the extensive microbiological diversity in such biotopes (8).Samples for geochemical and microbiological studies were retrieved from the northernmost brine-filled deeps of the Red Sea during the RV Meteor Cruise 52/3 in 2002. Isolation attempts with a samp...

Changes of resistome, mobilome and potential hosts of antibiotic resistance genes during the transformation of anaerobic digestion from mesophilic to thermophilic

“…S3). aadE is reported to be harbored by Haloplasma (Forslund et al, 2013), whose only type species, Haloplasma contractile, is mesophilic (Antunes et al, 2008). It is possible that some unknown thermophilic species in Haloplasma might be responsible for the observed relevance between aadE and Haloplasma.…”

Bacterial Shape: Two-Dimensional Questions and Possibilities

“…This assertion needs to be qualified and explained, because bacteria without such walls also have complicated morphologies (57, 82). Most impressively, a recently discovered wall-less organism in the Red Sea actively changes from a long straight filament to one with bumps, curls, curves and tightly wound spirals (3). In fact, this organism can extend a straight filamentous projection slimmer than the cell body, retract it into a tightly coiled spring-like structure, and re-extend it as a straight filament – all in the space of 8–10 seconds!…”

Halorhabdus tiamatea: proteogenomics and glycosidase activity measurements identify the first cultivated euryarchaeon from a deep‐sea anoxic brine lake as potential polysaccharide degrader

“…Among the most peculiar hypersaline habitats are deep‐sea brine lakes, like the Orca Basin in the Northern Gulf of Mexico (Pilcher and Blumstein, ), the ice‐sealed Antarctic Vida lake (Murray et al ., ), the numerous deep‐sea hypersaline anoxic lakes (DHALs) in the Eastern Mediterranean Sea (Bortoluzzi et al ., ) and the Red Sea (Antunes et al ., ). The thalassohaline DHAL Shaban Deep in the Red Sea was discovered in 1984 (Pautot et al ., ), and since several novel species were isolated from this location (Antunes et al ., 2003; 2007; 2008a,b). Halorhabdus tiamatea SARL4B T stems from the brine–sediment interface of the Shaban Deep's Eastern basin (26°13.9′ N, 35°21.3′ E, −1447 m depth, pH 6.0, salinity: 244) and features pleomorphic, non‐pigmented cells that grow chemoorganoheterotrophically under anoxic to micro‐oxic conditions [optimum: 45°C; pH 5.6–7.0; 27% NaCl (w/v)], but poorly under oxic conditions (Antunes et al ., ).…”