Biochemical Characterization of the Amylase Activity from the New Haloarchaeal Strain Haloarcula sp. HS Isolated in the Odiel Marshlands

Abstract

Alpha-amylases are a large family of α,1-4-endo-glycosyl hydrolases distributed in all kingdoms of life. The need for poly-extremotolerant amylases encouraged their search in extreme environments, where archaea become ideal candidates to provide new enzymes that are able to work in the harsh conditions demanded in many industrial applications. In this study, a collection of haloarchaea isolated from Odiel saltern ponds in the southwest of Spain was screened for their amylase activity. The strain that exhibited the highest activity was selected and identified as Haloarcula sp. HS. We demonstrated the existence in both, cellular and extracellular extracts of the new strain, of functional α-amylase activities, which showed to be moderately thermotolerant (optimum around 60 °C), extremely halotolerant (optimum over 25% NaCl), and calcium-dependent. The tryptic digestion followed by HPLC-MS/MS analysis of the partially purified cellular and extracellular extracts allowed to identify the sequence of three alpha-amylases, which despite sharing a low sequence identity, exhibited high three-dimensional structure homology, conserving the typical domains and most of the key consensus residues of α-amylases. Moreover, we proved the potential of the extracellular α-amylase from Haloarcula sp. HS to treat bakery wastes under high salinity conditions.

Amylolytic microorganisms from diverse tropical environments: Isolation, identification, and amylase production

“…All the isolates exhibited extracellular amylase activity as depicted by the presence of clearance zones or “halos” around their colonies after staining with Lugol's iodine reagent. The size of the halo zone is known generally to be proportional to amylase production [12,20]. The halo zone formation and SHR was then used as a semi‐quantitative method for classifying the isolates as excellent producers of amylases (SHR > 1.5), very good producers (SHR > 1 but <1.5), good producers (SHR > 0.5 but <1), and poor producers when no clear zones were observed.…”

“…Amylases have a wide range of industrial applications, including the food industry, especially in starch hydrolysis [22,23]. Currently, the food industry uses less active and/or unstable amylases to manufacture their products, leading to high costs of production [12].…”

“…The amylase production from different organisms exhibits broader variation since amylase production is dependent on media composition and physical parameters [1]. Moreover, the amylase enzymes in the industry are needed to work under harsh conditions, such as high temperatures, low/high pH, and different salt concentrations [12]. In Kenya and most of sub-Saharan Africa, enzymes for various purposes are imported [13].…”

Latest Advances in Protein-Recovery Technologies from Agricultural Waste

“…Amylase is recognized as a crucial industrial enzyme protein, comprising approximately 30% of the world enzyme market [20,21]. It is eminent for the food, fermentation, and pharmaceutical industries.…”

“…Some of the prominent conventional methods for the extraction and purification of enzymes are filtration, membrane extraction, precipitation, liquid-liquid extraction, ultrasonication, and chromatography, which are described in this review article, as well as advanced methods, including the liquid biphasic system (LBS), liquid biphasic flotation (LBF), thermoseparation (TMP), and three-phase partitioning (TPP). An efficient downstream processing method is needed to complete a large-scale purification of enzymes and protein to preserve their biological activity [20,21].…”