Antioxidant, Antimicrobial, and Bioactive Potential of Two New Haloarchaeal Strains Isolated from Odiel Salterns (Southwest Spain)

SIMPLE SUMMARY: Halophilic archaea are microorganisms that inhabit in extreme environments for life, under salt saturation, high temperature and elevated UV radiation. The interest in these microorganisms lies on the properties of their molecules, that present high salt and temperature tolerance, as well as, antioxidant power, being an excellent source of compounds for several biotechnological applications. However, the bioactive properties from haloarcahaea remain scarcely studied compared to other groups as plants or algae, usually reported as good health promoters. In this work we describe the isolation and the molecular identification of two new haloarchaeal strains from Odiel salterns (SW Spain), and the antioxidant, antimicrobial and bioactive potential of their extracts. The results revealed that the extracts obtained with acetone presented the highest activities in the antioxidant, antimicrobial and anti-inflammatory assays, becoming a promising source of metabolites with applied interest in pharmacy, cosmetics and food industry. ABSTRACT: The need to survive in extreme environments has furnished haloarchaea with a series of components specially adapted to work in such conditions. The possible application of these molecules in the pharmaceutical and industrial fields has received increasing attention; however, many potential bioactivities of haloarchaea are still poorly explored. In this paper, we describe the isolation and identification of two new haloarchaeal strains from the saltern ponds located in the marshlands of the Odiel River, in the southwest of Spain, as well as the in vitro assessment of their antioxidant, antimicrobial, and bioactive properties. The acetone extract obtained from the new isolated Haloarcula strain exhibited the highest antioxidant activity, while the acetone extracts from both isolated strains demonstrated a strong antimicrobial activity, especially against other halophilic microorganisms. Moreover, these extracts showed a remarkable ability to inhibit the enzyme cyclooxygenase-2 and to activate the melanogenic enzyme tyrosinase, indicating their potential against chronic inflammation and skin pigmentation disorders. Finally, the aqueous protein-rich extracts obtained from both haloarchaea exhibited an important inhibitory effect on the activity of the acetylcholinesterase enzyme, involved in the hydrolysis of cholinergic neurotransmitters and related to several neurological diseases.