Evaluation of historical and future coastal wetland change in the Yellow and Bohai Seas using satellite images and a land use model.

Predicting the future distribution of coastal wetlands and characterizing changes in the area of wetlands between historical and future periods are important for the formulation of wetland conservation and management plans. Here, we used a cellular automata-Markov model and satellite images to simulate the future distribution of coastal wetlands under the business-as-usual scenario (BAU) and ecological protection scenario (EP) along the Yellow and Bohai Seas in China; we also explored historical (from 1990 to 2020) and future (from 2020 to 2050) changes in wetlands and the factors driving these changes. We found that the area of tidal flats gradually decreased because of increases in the area of saltpans, and the aquaculture area increased because of land reclamation and the invasion of Spartina alterniflora; most of the tidal flat area was fragmented into multiple small patches. If the current rate of degradation continues (BAU), the area of tidal flats will decrease by 21.25%, and the area of saltpans and aquaculture will increase by 13.83% and 21.25%, respectively. By contrast, under EP, the area of tidal flats will increase by 13.81%, and this increase will mainly stem from the conversion of areas with S. alterniflora (174.49 km2, 33.22%) to aquaculture areas (155.17 km2, 29.54%). Clear differences between historical and future periods were observed among Liaohe Estuary, Bohai Bay, Laizhou Bay, and the Yancheng-Nantong coasts. Land reclamation is the main factor inducing changes in the area of tidal flats, saltpans, and aquaculture in Liaohe Estuary, Bohai Bay, and Laizhou Bay. Land reclamation and the S. alterniflora invasion both affect the distribution of wetlands along the Yancheng-Nantong coasts.

Identification of Multi-Potent Protein Subtilisin A from halophilic bacterium Bacillus firmus VE2.

Screening of halophiles with antimicrobial activity in saltpan soil samples from Nagapattinam district, Tamil Nadu, revealed isolate VE-2 as the most potent, identified as Bacillus firmus strain VE-2 through 16s rRNA gene sequencing. It had an optimum growth condition (OD 3.1) and antimicrobial protein (AMP) production (450 µg/mL) at 37 °C, pH 8, 25% NaCl, and 36 h incubation. SDS-PAGE analysis of the purified AMP showed the molecular weight of 36 kDa. HPLC analysis of the purified AMP showed different amino acids, such as asparagines, alanine, lysine, proline, threonine, glycine, cysteine, serine, aspartic acid leucine, and valine. Further characterization and identification using FT-IR, 2D-PAGE, MALDI-TOF, and in-silico analysis showed that the isolated AMP had the highest similarity to Subtilisin-A. It showed antibacterial activity against clinical bacterial pathogens like S. aureus, S. pyogenes, C. diphtheria, E. coli, and P. aeruginosa with the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration of 2.5 µg/mL and 20 µg/mL and also against various fungal pathogens such as A. niger, A. flavus, C. albicans, C. tropicalis and C. parapsilosis with the MIC and minimum fungicidal concentrations of 1.25-80 µg/mL. The purified AMP had excellent antioxidant potential, showed a scavenging effect against DPPH and Nitric oxide radicals, and displayed anticancer activity against HeLa cell lines with the IC50 values 53 µg/mL. Hence, the purified bioactive antimicrobial peptides (AMP) could also be used in anticancer therapies.

Anti-methicillin Resistant Staphylococcus aureus Compound Isolation from Halophilic Bacillus amyloliquefaciens MHB1 and Determination of Its Mode of Action Using Electron Microscope and Flow Cytometry Analysis.

The aim of this study was to purify, characterize and evaluate the antibacterial activity of bioactive compound against methicillin-resistant Staphylococcus aureus (MRSA). The anti-MRSA compound was produced by a halophilic bacterial strain designated as MHB1. The MHB1 strain exhibited 99 % similarity to Bacillus amyloliquefaciens based on 16S rRNA gene analysis. The culture conditions of Bacillus amyloliquefaciens MHB1 were optimized using nutritional and environmental parameters for enhanced anti-MRSA compound production. The pure bioactive compound was isolated using silica gel column chromatography and Semi-preparative High-performance liquid chromatography (Semi-preparative HPLC). The Thin layer chromatography, Fourier transform infrared spectroscopy and proton NMR ((1)H NMR) analysis indicated the phenolic nature of the compound. The molecular mass of the purified compound was 507 Da as revealed by Liquid chromatography-mass spectrometry (LC-MS) analysis. The compound inhibited the growth of MRSA with minimum inhibitory concentration (MIC) of 62.5 µg mL(-1). MRSA bacteria exposed to 4× MIC of the compound and the cell viability was determined using flow cytometric analysis. Scanning electron microscope and Transmission electron microscope analysis was used to determine the ultrastructural changes in bacteria. This is the first report on isolation of anti-MRSA compound from halophilic B. amyloliquefaciens MHB1 and could act as a promising biocontrol agent.

Microbial Communities in Saltpan Sediments Show Tolerance to Mars Analog Conditions, but Susceptibility to Chloride and Perchlorate Toxicity.

Brines at or near the surface of present-day Mars are a potential explanation for seasonally recurring dark streaks on the walls of craters, termed recurring slope lineae (RSL). Deliquescence and freezing point depression are possible drivers of brine stability, attributable to the high salinity observed in martian regolith including chlorides and perchlorates. Investigation of life, which may inhabit RSL, and the cellular mechanisms necessary for survival, must consider the tolerance of highly variable hydration, freeze-thaw cycles, and high osmolarity in addition to the anaerobic, oligotrophic, and irradiated environment. We propose the saltpan, an ephemeral, hypersaline wetland as an analogue for putative RSL hydrology. Saltpan sediment archaeal and bacterial communities showed tolerance of the Mars-analogous atmosphere, hydration, minerology, salinity, and temperature. Although active growth and a shift to well-adapted taxa were observed, susceptibility to low-concentration chloride and perchlorate addition suggested that such a composition was insufficient for beneficial water retention relative to added salt stress.

Evaluation of heavy metal pollutants in salt and seawater under the influence of the Lyari River and potential health risk assessment.

Heavy metals intoxication through edible salt poses serious health hazards. The conducted research assessed the levels of heavy metals, health risks of salt samples, and the pollution index of seawater obtained from saltpans located at Sandpit, Karachi, Pakistan, which receive untreated effluents through the Lyari River. Seawater (n = 27) and salt samples (n = 27) were prepared for the detection of Al, Cd, Pb, Cr, Fe, Cu, Hg, Ni, As and Zn through atomic absorption spectroscopy, mean concentrations ± S.D. (mg/mL) were compared with the National Environmental Quality Standards, Pakistan. The levels of Cr (40.06 ± 0.21) were the highest followed by Fe (39.77 ± 0.08) > As (25.12 ± 0.21) > Ni > Pb > Al > Hg > Zn > Cd > Cu. In sea salt (Mean ± S·D mg/Kg), the Cr (47.79 ± 0.19), Fe (47.5 ± 0.15), As (30.62 ± 0.22), and Ni were redundant elements followed by Al > Pb > Hg > Zn > Cu > Cd. The water comprehensive pollution index was 1000 times greater than the critical values. The single factor pollution index was highest for Hg (1321), followed by Cr (40), Ni (36), Pb (32), Al (31.4), Cd (31.3), and As (25). Health risk assessment indices (from salt samples), including target hazard quotient (THQ) for As, Pb, Al, Hg, and Cr were two to six times higher than the noncarcinogenic THQ reference range. Similarly, the hazardous index indicated that salt was 20 times hazardous (HI = 20.29), and the carcinogenic rate index for the heavy metals i.e., Cd, As, Cr, and Ni was above the reference CR value i.e., 1 × 10-4. In conclusion, the experimental and theoretical approaches recommend that the use of contaminated salt may impart health hazards.

CTAB influenced differential elution of metagenomic DNA from saltpan and marine sediments.

A simple, reliable method for genomic DNA extraction from sediments with minimum contaminants was developed to address the risk of poor quality DNA in metagenomic studies. Nine DNA extraction methods using 20% cetyl-trimethyl-ammonium bromide (CTAB) were performed and compared to develop an extraction protocol that can offer humic acid-free metagenomic DNA from marine and saltpan sediments. Community DNA extraction was executed via., Zhou et al. modified protocol using 20% CTAB treatment at different steps to compare the efficacy of humic acid removal. Out of nine DNA extraction methods, method 6 significantly improved the quality of DNA with efficient removal of humic substances. 16S rRNA gene amplification and spectrophotometric analysis confirmed the efficiency of method 6 to remove DNA inhibitors from marine sediments as well as saltpan samples. Inhibitors extracted along with metagenomic DNA outcome increased DNA yield and PCR inhibition in method 1 and 3. However, repeated 20% CTAB wash in method 6 ensured 16S amplification and least yield and concentration. Current study explains a detailed protocol based on 20% CTAB wash for the extraction of humic acid-free DNA from diverse sediment samples.

Can volatile organic compounds be markers of sea salt?

Sea salt is a handmade food product that is obtained by evaporation of seawater in saltpans. During the crystallisation process, organic compounds from surroundings can be incorporated into sea salt crystals. The aim of this study is to search for potential volatile markers of sea salt. Thus, sea salts from seven north-east Atlantic Ocean locations (France, Portugal, Continental Spain, Canary Islands, and Cape Verde) were analysed by headspace solid-phase microextraction combined with comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry. A total of 165 compounds were detected, ranging from 32 to 71 compounds per salt. The volatile composition revealed the variability and individuality of each salt, and a set of ten compounds were detected in all samples. From these, seven are carotenoid-derived compounds that can be associated with the typical natural surroundings of ocean hypersaline environment. These ten compounds are proposed as potential volatile markers of sea salt.

Phylogenetic characterization of archaea in saltpan sediments.

A study was undertaken to investigate the presence of archaeal diversity in saltpan sediments of Goa, India by 16S rDNA-dependent molecular phylogeny. Small subunit rRNA (16S rDNA) from saltpan sediment metagenome were amplified by polymerase chain reaction (PCR) using primers specific to the domain archaea. 10 unique phylotypes were obtained by PCR based RFLP of 16S rRNA genes using endonuclease Msp 1, which was most suitable to score the genetic diversity. These phylotypes spanned a wide range within the domain archaea including both crenarchaeota and euryarcheaota. None of the retrieved crenarchaeota sequences could be grouped with previously cultured crenarchaeota however; two sequences were related with haloarchaea. Most of the sequences determined were closely related to the sequences that had been previously obtained from metagenome of a variety of marine environments. The phylogenetic study of a site investigated for the first time revealed the presence of low archaeal population but showed yet unclassified species, may specially adapted to the salt pan sediment of Goa.