Exploring Marine Environments for the Identification of Extremophiles and Their Enzymes for Sustainable and Green Bioprocesses

Sea environments harbor a wide variety of life forms that have adapted to live in hard and sometimes extreme conditions. Among the marine living organisms, extremophiles represent a group of microorganisms that attract increasing interest in relation to their ability to produce an array of molecules that enable them to thrive in almost every marine environment. Extremophiles can be found in virtually every extreme environment on Earth, since they can tolerate very harsh environmental conditions in terms of temperature, pH, pressure, radiation, etc. Marine extremophiles are the focus of growing interest in relation to their ability to produce biotechnologically useful enzymes, the so-called extremozymes. Thanks to their resistance to temperature, pH, salt, and pollutants, marine extremozymes are promising biocatalysts for new and sustainable industrial processes, thus representing an opportunity for several biotechnological applications. Since the marine microbioma, i.e., the complex of microorganisms living in sea environments, is still largely unexplored finding new species is a central issue for green biotechnology. Here we described the main marine environments where extremophiles can be found, some existing or potential biotechnological applications of marine extremozymes for biofuels production and bioremediation, and some possible approaches for the search of new biotechnologically useful species from marine environments

Production of succinic acid from Basfia succiniciproducens up to the pilot scale from Arundo donax hydrolysate.

Abstract In the present work the recently isolated strain Basfia succiniciproducens BPP7 was evaluated for the production of succinic acid up to the pilot fermentation scale in separate hydrolysis and fermentation experiments on Arundo donax, a non-food dedicated energy crop. An average concentration of about 17 g/L of succinic acid and a yield on consumed sugars of 0.75 mol/mol were obtained demonstrating strain potential for further process improvement. Small scale experiments indicated that the concentration of acetic acid in the medium is crucial to improve productivity; on the other hand, interestingly, short-term (24 h) adaptation to higher acetic acid concentrations, and strain recovery, were also observed

Degradative actions of microbial xylanolytic activities on hemicelluloses from rhizome of Arundo donax

Polysaccharidases from extremophiles are remarkable for specific action, resistance to different reaction conditions and other biotechnologically interesting features. In this article the action of crude extracts of thermophilic microorganisms (Thermotoga neapolitana, Geobacillus thermantarcticus and Thermoanaerobacterium thermostercoris) is studied using as substrate hemicellulose from one of the most interesting biomass crops, the giant reed (Arundo donax L.). This biomass can be cultivated without competition and a huge amount of rhizomes remains in the soil at the end of cropping cycle (10–15 years) representing a further source of useful molecules. Optimization of the procedure for preparation of the hemicellulose fraction from rhizomes of Arundo donax, is studied. Polysaccharidases from crude extracts of thermophilic microorganisms revealed to be suitable for total degradative action and/or production of small useful oligosaccharides from hemicelluloses from A. donax. Xylobiose and interesting tetra- and pentasaccharide are obtained by enzymatic action in different conditions. Convenient amount of raw material was processed per mg of crude enzymes. Raw hemicelluloses and pretreated material show antioxidant activity unlike isolated tetra- and pentasaccharide. The body of results suggest that rhizomes represent a useful raw material for the production of valuable industrial products, thus allowing to increase the economic efficiency of A. donax cultivation

Extremophiles' relevance for the production of second generation bioethanol

The ever growing concerns about the threats of first generation bioethanol on food supplies and biodiversity have shifted the focus of research to second generation biofuel technologies. The second generation bioethanol's technologies provide sustainable energy without compromising food security and environment since they exploit non-food crops or non-food parts of crops and wastes of wood-based or food-based industries such as wood chips, skins and pulp from fruit pressing. The key step of the bioethanol's production processes is represented by the hydrolysis of the biomass to C5 and C6 sugars: such process relies on the use of bacterial enzymes that are mainly derived from extremophilic microorganisms. These microorganisms can be found in extreme environments, generally characterized by atypical temperature, pH, pressure, salinity, toxicity and radiation levels. Their enzymes (also named extremozymes) possess unique properties of considerable biotechnological significance that make them very useful for the industrial transformation of biomass to ethanol. In this report a survey of extremophiles and related enzymes that have been used for the bioconversion of waste biomass (not in competition with food chain) to bioethanol, is given

The production of second generation bioethanol: The biotechnology potential of thermophilic bacteria

The ever growing concerns about the impact of first generation bioethanol on food chain and on biodiversity have shifted the focus of research to second generation (2G) bioethanol technologies. The 2G-bioethanol's production relies on biomass feedstock that could provide a more sustainable energy generation without compromising food security and environment. Indeed, this production process exploits non-food crops, food crops residues, wastes of wood-based or food-based industries such as wood chips, skins or pulps from fruit pressing, respectively. Nevertheless, the industrial process of 2G-bioethanol's production is still in its infancy, indeed the future and the sustainability of the 2G-bioethanol strongly depend upon the development of the current technology. In this paper particular attention will be paid to the role of thermophilic microorganisms and their enzymes to the biotechnology's development of the bioethanol's production process

Biotechnology Implications of Extremophiles as Life Pioneers and Wellspring of Valuable Biomolecules

Studies on extremophiles, microorganisms able to survive in extreme environments, are very helpful for the comprehension of life evolution; in fact they are the unique organisms of the Earth at the origin of life. They lie into the three domains of life (Archaea, Bacteria, and Eukarya) and can be found in environmental niches on Earth such as in hydrothermal vents and springs, in salty lakes, in halite crystals, in polar ice and lakes, in volcanic areas, in deserts, or under anaerobic conditions. The existence of life forms beyond the Earth requires an extension of the classical limits of life: the resistance of extremophilic organisms to harsh conditions in terms of temperature, salinity, pH, pressure, dryness, and desiccation makes these living organisms good putative candidates to assess the habitability of other planets. The ability to survive and proliferate in extreme conditions (pH, temperature, pressure, salt, and nutrients) produces a variety of biotechnologically useful molecules such as lipids, enzymes, polysaccharides, and compatible solutes that are employed in several industrial processes. There are many extremophilic enzymes and also endogenous compounds that are used with success for food industry, for preparation of the detergents, for pharmacological applications, and also for genetic studies. In particular enzymes that derive from thermophiles, and for this reason called thermozymes, represent an excellent sources of new catalysts of interest in industrial sectors

Microbial Diversity in Extreme Marine Habitats and Their Biomolecules

Extreme marine environments have been the subject of many studies and scientific publications. For many years, these environmental niches, which are characterized by high or low temperatures, high-pressure, low pH, high salt concentrations and also two or more extreme parameters in combination, have been thought to be incompatible to any life forms. Thanks to new technologies such as metagenomics, it is now possible to detect life in most extreme environments. Starting from the discovery of deep sea hydrothermal vents up to the study of marine biodiversity, new microorganisms have been identified, and their potential uses in several applied fields have been outlined. Thermophile, halophile, alkalophile, psychrophile, piezophile and polyextremophile microorganisms have been isolated from these marine environments; they proliferate thanks to adaptation strategies involving diverse cellular metabolic mechanisms. Therefore, a vast number of new biomolecules such as enzymes, polymers and osmolytes from the inhabitant microbial community of the sea have been studied, and there is a growing interest in the potential returns of several industrial production processes concerning the pharmaceutical, medical, environmental and food fields

Molecular Characterization of Extracts from Biorefinery Wastes and Evaluation of Their Plant Biostimulation

Lignin was isolated with subcritical water:ethanol:CO2 (Sub-CW) from biorefinery biomasses, such as giant reed (AD) and miscanthus (MG), with recovery yields about 30% on Klason lignin. Their structural composition assessed by IR and NMR techniques, as well as Derivatization Followed by Reductive Cleavage (DFRC/GC-MS). The 2D HSQC-NMR spectra elucidated that the Sub-CW extracts contained different lignin dimers and co-extracted carbohydrates. The DFRC/GC-MS revealed that syringyl molecules were more abundant in AD, while guaiacyl monomers were predominant in MG. Lignin residues were derivatized with phospholane to quantitatively estimate the amount of OH groups by 31P NMR, showing a marked predominance of aliphatic units for both lignins, due to the presence of either hydroxyls in lignin side-chain or residual carbohydrates. Lignin residues derivatized with phospholane allowed to record 31P-DOSY NMR spectra. AD-lignin showed a smaller diffusivity constant than for MG-substrate, possibly because of the larger content of disaccharides in MG lignin. We showed that the molecular composition of lignin isolated by the Sub-CW technique may differ depending on the type of biomass used for the extraction, suggesting a different industrial application of lignin from various biomass