High levels of microplastics in commercial salt and industrial salterns in Sri Lanka

This study provides the first analysis and quantification of MPs in salt products in Sri Lanka. Commercial table salt brands, rock salt, lab-grade NaCl and raw salt from three salterns were analysed using microscopy and Fourier transform infrared spectroscopy. All salt samples were contaminated with MPs: in commercial salts products it ranged from 11 to 193 items/kg, rock salts had 64 items/kg and lab grade NaCl had 253 ± 8.9 items/kg. The MP levels in salterns varied significantly: Hambantota 3345.7 ± 311.4 items/kg, Puttalam 272.3 ± 10.6 items/kg, and Elephant Pass 36.3 ± 4.5 items/kg. Predominantly, MPs were presented as fibres, followed by fragments. Of the 23 polymer types identified; low-density polyethylene (LDPE; 17%), resin dispersion (15%) and high-density polyethylene (HDPE; 12%) were notable. This study provides the first comparison of MPs in raw salt and commercial salt. This information is important to trace the pollutant sources and then to take steps to eliminate MPs in food products consumed.

Settling taxonomic and nomenclatural problems in brine shrimps, Artemia (Crustacea: Branchiopoda: Anostraca), by integrating mitogenomics, marker discordances and nomenclature rules

High morphological plasticity in populations of brine shrimp subjected to different environmental conditions, mainly salinity, hindered for centuries the identification of the taxonomic entities encompassed within Artemia. In addition, the mismatch between molecular and morphological evolution rates complicates the characterization of evolutionary lineages, generating taxonomic problems. Here, we propose a phylogenetic hypothesis for Artemia based on two new complete mitogenomes, and determine levels of congruence in the definition of evolutionary units using nuclear and mtDNA data. We used a fossil of Artemia to calibrate the molecular clock and discuss divergence times within the genus. The hypothesis proposed herein suggests a more recent time frame for lineage splitting than previously considered. Phylogeographic analyses were performed using GenBank available mitochondrial and nuclear markers. Evidence of gen e flow, identified through discordances between nuclear and mtDNA markers, was used to reconsider the specific status of some taxa. As a result, we consider Artemia to be represented by five evolutionary units: Southern Cone, Mediterranean-South African, New World, Western Asian, and Eastern Asian Lineages. After an exhaustive bibliographical revision, unavailable names for nomenclatural purposes were discarded. The remaining available names have been assigned to their respective evolutionary lineage. The proper names for the evolutionary units in which brine shrimps are structured remain as follows: Artemia persimilis Piccinelli & Prosdocimi, 1968 for the Southern Cone Lineage, Artemia salina (Linnaeus, 1758) for the Mediterranean-SouthAfrican Lineage, Artemia urmiana Günther, 1899 for the Western Asian Lineage, and Artemia sinica Cai, 1989 for the Eastern Asian Lineage. The name Artemia monica Verrill, 1869 has nomenclatural priority over A. franciscana Kellogg, 1906 for naming the New World Lineage. New synonymies are proposed for A. salina (= C. dybowskii Grochowski, 1896 n. syn., and A. tunisiana Bowen & Sterling, 1978 n. syn.), A. monica (= A. franciscana Kellogg, 1906 n. syn., and A. salina var. pacifica Sars, 1904 n. syn.); A. urmiana (= B. milhausenii Fischer de Waldheim, 1834 n. syn., A. koeppeniana Fischer, 1851 n. syn., A. proxima King, 1855 n. syn., A. s. var. biloba Entz, 1886 n. syn., A. s. var. furcata Entz, 1886 n. syn., A. asiatica Walter, 1887 n. syn., A. parthenogenetica Bowen & Sterling, 1978 n. syn., A. ebinurica Qian & Wang, 1992 n. syn., A. murae Naganawa, 2017 n. syn., and A. frameshifta Naganawa & Mura, 2017 n. syn.). Internal deep nuclear structuring within the A. monica and A. salina clades, might suggest the existence of additional evolutionary units within these taxa.

The microbiology of red brines

The brines of natural salt lakes with total salt concentrations exceeding 30% are often colored red by dense communities of halophilic microorganisms. Such red brines are found in the north arm of Great Salt Lake, Utah, in the alkaline hypersaline lakes of the African Rift Valley, and in the crystallizer ponds of coastal and inland salterns where salt is produced by evaporation of seawater or some other source of saline water. Red blooms were also reported in the Dead Sea in the past. Different types of pigmented microorganisms may contribute to the coloration of the brines. The most important are the halophilic archaea of the class Halobacteria that contain bacterioruberin carotenoids as well as bacteriorhodopsin and other retinal pigments, β-carotene-rich species of the unicellular green algal genus Dunaliella and bacteria of the genus Salinibacter (class Rhodothermia) that contain the carotenoid salinixanthin and the retinal protein xanthorhodopsin. Densities of prokaryotes in red brines often exceed 2-3×10⁷ cells/mL. I here review the information on the biota of the red brines, the interactions between the organisms present, as well as the possible roles of the red halophilic microorganisms in the salt production process and some applied aspects of carotenoids and retinal proteins produced by the different types of halophiles inhabiting the red brines.

The beauty and the yeast: can the microalgae Dunaliella form a borderline lichen with Hortaea werneckii?

Lichenized fungi usually develop complex, stratified morphologies through an intricately balanced living together with their algal partners, but several species are known to form only more or less loose associations with algae. These borderline lichens are still little explored although they could inform us about early stages of lichen evolution. We studied the association of the extremely halotolerant fungus Hortaea werneckii with the alga Dunaliella atacamensis, discovered in a cave in the Atacama Desert (Chile), and with D. salina, common inhabitant of saltern brines. D. atacamensis forms small colonies, in which cells of H. werneckii can be frequently observed, while such interaction has not been observed with D. salina. As symbiotic interactions between Dunaliella and Hortaea have not been reported, we performed a series of co-cultivation experiments to inspect whether these species could interact and develop more distinct lichen-like symbiotic structures. We set up co-cultures between axenic strains of Hortaea werneckii (isolated both from Mediterranean salterns and from the Atacama cave) and isolates of D. atacamensis (from the Atacama cave) and D. salina (isolated from Mediterranean salterns). Although we used different growth media and cultivation approaches, bright field and SEM microscopy analyses did not indicate any mutual effects in these experiments. We discuss the implications for fungal algal interactions along the transition from algal exploiters to lichen symbioses.

Selection of an indicator to assess a highly modified saline ecosystem

The Water Framework Directive (WFD, 2000/60/EC) determines that all water bodies must achieve a good ecological status. The solar salterns system of Mata-Torrevieja (Spain) has been designated as Heavily Modified Water Bodies (HMWB). This ecosystem is a transitional water body (TW) largely conditioned by socio-economic management plan and the related human activities that take place. Thus, WFD establishes as obligatory the determination of their ecological potential, and not their ecological status. In order to define the ecological potential, it is necessary to determine previously the chemical and biological conditions of the water body. This paper is focused on the analysis of physical-chemical parameters of a saltern system during 2008-2016, in order to establish a starting point for the implementation process of the WFD in this type of ecosystem (TW-HMWB). The behavior of salinity and physical-chemical parameters (temperature, pH, nutrients) has been studied. Salinity was the most relevant parameter studied to define pressures for these water bodies. However, total phosphorus turned out to be a good potential status indicator. It would be one of the most suitable chemical parameters to propose a methodology for the determination of the ecological potential in the salterns.

Culturable bacteria from two Portuguese salterns: diversity and bioactive potential

Salterns are extreme environments, where the high salt concentration is the main limitation to microbial growth, along with solar radiation, temperature and pH. These selective pressures might lead to the acquisition of unique genetic adaptations that can manifest in the production of interesting natural products. The present study aimed at obtaining the culturable microbial diversity from two Portuguese salterns located in different geographic regions. A total of 190 isolates were retrieved and identified as belonging to 30 genera distributed among 4 phyla-Firmicutes, Proteobacteria, Actinobacteria and Bacteroidetes. Specifically, members of the genus Bacillus were the most frequently isolated from both salterns and all actinobacterial isolates belong to the rare members of this group. The molecular screening of NRPS and PKS-I genes allowed the detection of 38 isolates presenting PKS-I, 25 isolates presenting NRPS and 23 isolates presenting both types of biosynthetic genes. Sequencing of randomly selected amplicons revealed similarity with known PKS-I and NRPS genes or non-annotated hypothetical proteins. This study is the first contribution on the culturable bacterial diversity of Portuguese salterns and on their bioactive potential. Ultimately, these findings provide a novel contribution to improve the understanding on the microbial diversity of salterns.

Efficacy of Alpha Glucosidase Inhibitor from Marine Actinobacterium in the Control of Postprandial Hyperglycaemia in Streptozotocin (STZ) Induced Diabetic Male Albino Wister Rats

The current study was carried out to evaluate the in-vitro and in-vivo efficiency of alpha glucosidase inhibitor of marine actinobacteria in the control of postprandial hyperglycaemia. Soil samples were collected from salterns, coastal area in Kothapatnam, Ongole, Andhra Pradesh, India. Among the actinobacterial isolates tested for yeastα-glucosidase inhibitory activity, only three isolates showed prominent inhibition. The patient isolate was selected and identified as Streptomyces coelicoflavus SRBVIT13 using 16S r-RNA gene sequencing. In in-vitro studies, the chloroform extract of Streptomyces coelicoflavus SRBVIT13 showed significant enzyme inhibitory activity against yeast and mammalian α-glucosidaseenzymes. In animal studies, the oral ingestion of chloroform extract (600 mg/kg) of S. coelicoflavus SRBVIT13 in maltose and sucrose loaded diabetic rats, showed significant regulation of postprandial blood glucose by 82.25% and a 77.25% reduction, respectively. The lead compound from S. coelicoflavusSRBVIT13 was isolated, purified, characterized, and identified by stranded analytical techniques as 2-t-butyl-5-chloromethyl-3-methyl-4-oxoimidazolidine-1-carboxylic acid, t-butyl ester. The results obtained in the present study are promising and the bioactive compound from S. coelicoflavusSRBVIT13 may be considered as a potential agent in regulating the postprandial hyperglycaemia.

Salinivibrio kushneri sp. nov., a moderately halophilic bacterium isolated from salterns

Ten Gram-strain-negative, facultatively anaerobic, moderately halophilic bacterial strains, designated AL184^T, IB560, IB563, IC202, IC317, MA421, ML277, ML318, ML328A and ML331, were isolated from water ponds of five salterns located in Spain. The cells were motile, curved rods and oxidase and catalase positive. All of them grew optimally at 37°C, at pH 7.2-7.4 and in the presence of 7.5% (w/v) NaCl. Based on phylogenetic analyses of the 16S rRNA, the isolates were most closely related to Salinivibrio sharmensis BAG^T (99.6-98.2% 16S rRNA gene sequence similarity) and Salinivibrio costicola subsp. costicola ATCC 35508^T (99.0-98.1%). According to the MLSA analyses based on four (gyrB, recA, rpoA and rpoD) and eight (ftsZ, gapA, gyrB, mreB, pyrH, recA, rpoA and topA) concatenated gene sequences, the most closely relatives were S. siamensis JCM 14472^T (96.8-95.4% and 94.9-94.7%, respectively) and S. sharmensis DSM 18182^T (94.0-92.6% and 92.9-92.7%, respectively). In silico DNA-DNA hybridization (GGDC) and average nucleotide identity (ANI) showed values of 23.3-44.8% and 80.2-91.8%, respectively with the related species demonstrating that the ten isolates constituted a single novel species of the genus Salinivibrio. Its pangenome and core genome consist of 6041 and 1230 genes, respectively. The phylogeny based on the concatenated orthologous core genes revealed that the ten strains form a coherent phylogroup well separated from the rest of the species of the genus Salinivibrio. The major cellular fatty acids of strain AL184^T were C_16:0 and C_18:1. The DNA G+C content range was 51.9-52.5mol% (T_m) and 50.2-50.9mol% (genome). Based on the phylogenetic-phylogenomic, phenotypic and chemotaxonomic data, the ten isolates represent a novel species of the genus Salinivibrio, for which the name Salinivibrio kushneri sp. nov. is proposed. The type strain is AL184^T (=CECT 9177^T=LMG 29817^T).

Biogeographical patterns of bacterial and archaeal communities from distant hypersaline environments

Microorganisms are globally distributed but new evidence shows that the microbial structure of their communities can vary due to geographical location and environmental parameters. In this study, 50 samples including brines and sediments from Europe, Spanish-Atlantic and South America were analysed by applying the operational phylogenetic unit (OPU) approach in order to understand whether microbial community structures in hypersaline environments exhibited biogeographical patterns. The fine-tuned identification of approximately 1000 OPUs (almost equivalent to "species") using multivariate analysis revealed regionally distinct taxa compositions. This segregation was more diffuse at the genus level and pointed to a phylogenetic and metabolic redundancy at the higher taxa level, where their different species acquired distinct advantages related to the regional physicochemical idiosyncrasies. The presence of previously undescribed groups was also shown in these environments, such as Parcubacteria, or members of Nanohaloarchaeota in anaerobic hypersaline sediments. Finally, an important OPU overlap was observed between anoxic sediments and their overlaying brines, indicating versatile metabolism for the pelagic organisms.

Biosorption of lead, copper and cadmium using the extracellular polysaccharides (EPS) of Bacillus sp., from solar salterns

Extracellular Polysaccharides (EPS) from both prokaryotes and eukaryotes have a great deal of research interest as they protect the producer from different stresses including antibiotics, ionic stress, desiccation and assist in bio-film formation, pathogenesis, adhesion, etc. In this study haloalkaliphilic Bacillus sp., known to cope with osmophilic stress, was selected and screened for EPS production. The EPS were isolated, partially purified and chemical characteristics were documented using liquid FT-IR followed by assessment of heavy metal biosorption (lead, copper and cadmium) using Atomic Absorption Spectroscopy (AAS). The EPS extracted from three isolates B. licheniformis NSPA5, B. cereus NSPA8 and B. subtilis NSPA13 showed maximum biosorption of Lead followed by Copper and Cadmium. Of the tested isolates, the EPS from isolate B. cereus NSPA8 showed maximum (90 %) biosorption of the lead.

The ecology of Dunaliella in high-salt environments

Halophilic representatives of the genus Dunaliella, notably D. salina and D. viridis, are found worldwide in salt lakes and saltern evaporation and crystallizer ponds at salt concentrations up to NaCl saturation. Thanks to the biotechnological exploitation of D. salina for β-carotene production we have a profound knowledge of the physiology and biochemistry of the alga. However, relatively little is known about the ecology of the members of the genus Dunaliella in hypersaline environments, in spite of the fact that Dunaliella is often the main or even the sole primary producer present, so that the entire ecosystem depends on carbon fixed by this alga. This review paper summarizes our knowledge about the occurrence and the activities of different Dunaliella species in natural salt lakes (Great Salt Lake, the Dead Sea and others), in saltern ponds and in other salty habitats where members of the genus have been found.