A novel biotechnological process has been developed for the isolation of desiccation-tolerant microorganisms and their xeroprotectants, i.e., compatible solutes involved in long-term stability of biomolecules in the dry state. Following exposure of soil samples to chloroform, we isolated a collection of desiccation-tolerant microorganisms. This collection was screened for the production of xeroprotectants by a variation of the bacterial milking (osmotic downshock) procedure and by a novel air-drying/rehydration ("dry milking") incubation method. The resultant solutes were shown to protect both proteins and living cells against desiccation damage, thereby validating them as xeroprotectants. Nuclear magnetic resonance (NMR) analytical studies were performed to identify the xeroprotectants; synthetic mixtures of these compounds were shown to perform similarly to natural isolates in drying experiments with proteins and cells. This new approach has biotechnological and environmental implications for the identification of new xeroprotectants of commercial and therapeutic value.Some microorganisms accumulate small organic compounds in response to changing extracellular osmolarity, as with desiccation or addition of salts (2, 8). These compatible solutes, e.g., the disaccharide trehalose or the hydroxypyrimidine hydroxyectoine, act as osmoprotectants but under laboratory conditions can also stabilize enzymes, DNA, membranes, and even whole cells against different kinds of stress, such as freezing, drying, and heating (8,18,21,37). A further benefit of nonreducing sugars such as trehalose is that they do not undergo damaging Maillard reactions with amino acids or proteins in the dry state; they therefore offer excellent protection to biomolecules and even living cells during desiccation (9,12,15). In consequence, there is great biotechnological interest in these solutes, since many different biomolecules and cells require stabilization to allow long-term storage for commercial use (4,24,35). Those compatible solutes that ensure long-term storage stability in the dry state (10, 11, 13) we term "xeroprotectants." Different biomolecules or cells are protected to different degrees depending on the xeroprotectants that are used (21). Therefore, new xeroprotectants together with new formulations are likely to be needed to preserve a wide range of desiccation-sensitive biomolecules and cell types, such as some vaccines, mammalian cells, or even whole tissues (30).In order to obtain large amounts of some compatible solutes (ectoine and hydroxyectoine), Sauer and Galinski (25) developed a technology termed bacterial milking. This technology is based on incubation of appropriate cells (i.e., Halomonas elongata) under hyperosmotic conditions followed by a transfer of the cells to low-salinity medium (osmotic downshock), which results in the release of the compatible solutes into the medium. Here we have used a variation of the bacterial milking method and have also developed a new technique for extracting xeroprotectants by slowly ...

The DNA molecule is associated with the role of encoding information required to produce RNA which is translated into proteins needed by the cell. This encoding involves information transmission to offspring or to other organisms by horizontal transfer. However, despite the abundance of this molecule in both the cell and the environment, its physiological role seems to be restricted mainly to that of a coding and inheritance molecule. In this paper, we report a new physiological role for the DNA molecule as involved in protection against desiccation, in addition to its well-established main information transfer and other recently reported functions such as bio-film formation in eDNA form. Desiccation-tolerant microorganisms such as Microbacterium sp. 3J1 significantly upregulate genes involved in DNA synthesis to produce DNA as part of their defensive mechanisms to protect protein structures and functions from drying according to RNA-seq analysis. We have observed the intracellular overproduction of DNA in two desiccation-tolerant microorganisms, Microbacterium sp. 3J1 and Arthrobacter siccitolerans 4J27, in response to desiccation signals. In addition, this conclusion can be made from our observations that synthetic DNA protects two proteins from drying and when part of a xeroprotectant preparation, DNA from various organisms including desiccation-sensitive species, does the same. Removal of DNA by nuclease treatment results in absence of this additive protective effect. We validated this role in biochemical and biophysical assays in proteins and occurs in trans even with short, single chains of synthetically produced DNA.

Arthrobacter koreensis 5J12A is a desiccation-tolerant organism isolated from the Nerium oleander rhizosphere. Here, we report its genome sequence, which may shed light on its role in plant growth promotion. This is believed to be the first published genome of a desiccation-tolerant plant growth promoter from the genus Arthrobacter.

The genome sequence for Microbacterium sp. strain 3J1, a desiccation-tolerant organism isolated from the Nerium oleander rhizosphere, is reported here. The genome is estimated to be approximately 3.5 Mb in size, with an average G+C content of 67.7% and a predicted number of protein-coding sequences of 3,310.

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