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

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.

Analysis of Carotenoids in Haloarchaea Species from Atacama Saline Lakes by High Resolution UHPLC-Q-Orbitrap-Mass Spectrometry: Antioxidant Potential and Biological Effect on Cell Viability

“…In particular, AChE inhibition IC 50 was 2.96 ± 0.08 mg mL −1 and BuChE inhibition IC 50 was 2.39 ± 0.09 mg mL −1 for the most active strain, Te Se-85, respectively, ( Table 2 ), which is more active in BuChE than that of the standard galantamine ( Table 2 ). This is in accordance with previous results of the inhibition of these enzymes on other investigated extremophile strains (but only reported in percentage, with a maximum 40% inhibition for the AChE enzyme for the strains Haloarcula hispanica and Halobacterium salinarum for chloroform and ethyl acetate extracts of the strains) [ 33 ].…”

“…The DPPH scavenging activity of our strains was shown to be similar to that of the extremophiles Aquisalibacillus elongatus MB592 [ 17 ] (80 percent inhibition of DPPH radical at 5–30 μg/mL). The haloarchaea Halorubrum tebenquichense Te Se-86 showed the highest radical trapping ability (59.14 ± 9.54 μmol Trolox/g extract, (IC 50 = 2.95 ± 0.02 μg/mL), which is close to that exhibited by Haloarcula hispanica [ 33 ], followed by Halorubrum tebenquichense TeSe-85 (55.43 ± 3.26 μmol Trolox/g extract, IC 50 = 4.73 ± 0.02 μg/mL); Haloarcula sp. TeSe-41 (41.11 ± 6.02 μmol Trolox/g extract) and Haloarcula sp.…”

“…The absorbance was then measured at 765 nm after 6 min of reaction, and astaxanthin was used as a reference standard (curve from 10–250 μg/mL). The results were expressed as TEAC, in Trolox micromoles per gram of extract (μmol Trolox/g extract) and also as IC 50 in μg·mL −1 , (concentration of infusion or standard in μg·mL −1 required to inhibit 50% of DPPH radical present in solution) [ 32 , 33 ]. A Synergy HTX Multi-Mode Microplate Reader (BioTek Instruments Inc., Winoosky, VT, USA) was used.…”

The Methods of Digging for “Gold” within the Salt: Characterization of Halophilic Prokaryotes and Identification of Their Valuable Biological Products Using Sequencing and Genome Mining Tools

“…Finally, halophilic prokaryotes are the established producers of multiple biomolecules and chemical substances, predominantly osmolytes, hydrolytic enzymes, and pigments (e.g., carotenoids) [22,[87][88][89][90]. The increasing interest in compounds and proteins of halophilic origin results mainly from the fact that they remain active under harsh conditions like high salinity, extreme temperatures, and ultimate pH [91]. Moreover, halophilic enzymes retain solubility and solvation in low water activity [11], and as has been shown recently, they demonstrate anti-desiccation and antifreeze properties, so desirable in food processing and preservation [88].…”

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

“…Metagenomic microbial profiling by high-throughput 16S rRNA sequencing revealed the existence of various strains that belonged to the Haloarcula genus. Although the abundance of these representatives was quite low, with less than 0.2% of the total sequenced reads, our data suggest that some of the haloarchaea of this group are able to produce bioactive compounds [ 18 ] and excrete hydrolytic haloenzymes, including proteases, amylases, or lipases [ 17 ].…”