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

Fermentation Technologies for the Optimization of Marine Microbial Exopolysaccharide Production

In the last decades, research has focused on the capabilities of microbes to secrete exopolysaccharides (EPS), because these polymers differ from the commercial ones derived essentially from plants or algae in their numerous valuable qualities. These biopolymers have emerged as new polymeric materials with novel and unique physical characteristics that have found extensive applications. In marine microorganisms the produced EPS provide an instrument to survive in adverse conditions: They are found to envelope the cells by allowing the entrapment of nutrients or the adhesion to solid substrates. Even if the processes of synthesis and release of exopolysaccharides request high-energy investments for the bacterium, these biopolymers permit resistance under extreme environmental conditions. Marine bacteria like Bacillus, Halomonas, Planococcus, Enterobacter, Alteromonas, Pseudoalteromonas, Vibrio, Rhodococcus, Zoogloea but also Archaea as Haloferax and Thermococcus are here described as EPS producers underlining biopolymer hyperproduction, related fermentation strategies including the effects of the chemical composition of the media, the physical parameters of the growth conditions and the genetic and predicted experimental design tools

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

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

Involvement of a Quorum Sensing Signal Molecule in the Extracellular Amylase Activity of the Thermophilic Anoxybacillus amylolyticus

Anoxybacillus amylolyticus is a moderate thermophilic microorganism producing an exopolysaccharide and an extracellular α-amylase able to hydrolyze starch. The synthesis of several biomolecules is often regulated by a quorum sensing (QS) mechanism, a chemical cell-to-cell communication based on the production and diffusion of small molecules named “autoinducers”, most of which belonging to the N-acyl homoserine lactones’ (AHLs) family. There are few reports about this mechanism in extremophiles, in particular thermophiles. Here, we report the identification of a signal molecule, the N-butanoyl-homoserine lactone (C4-HSL), from the milieu of A. amylolyticus. Moreover, investigations performed by supplementing a known QS inhibitor, trans-cinnamaldehyde, or exogenous C4-HSL in the growth medium of A. amylolyticus suggested the involvement of QS signaling in the modulation of extracellular α-amylase activity. The data showed that the presence of the QS inhibitor trans-cinnamaldehyde in the medium decreased amylolytic activity, which, conversely, was increased by the effect of exogenous C4-HSL. Overall, these results represent the first evidence of the production of AHLs in thermophilic microorganisms, which could be responsible for a communication system regulating thermostable α-amylase activity