Assessment of Morpho-Physiological and Biochemical Responses of Mercury-Stressed Trigonella foenum-gracum L. to Silver Nanoparticles and Sphingobacterium ginsenosidiumtans Applications

Heavy metals are primarily generated and deposited in the environment, causing phytotoxicity. This work evaluated fenugreek plants’ morpho-physiological and biochemical responses under mercury stress conditions toward Ag nanoparticles and Sphingobacterium ginsenosidiumtans applications. The fabrication of Ag nanoparticles by Thymus vulgaris was monitored and described by UV/Vis analysis, FTIR, and SEM. The effect of mercury on vegetative growth was determined by measuring the root and shoots length, the number and area of leaves, the relative water content, and the weight of the green and dried plants; appraisal of photosynthetic pigments, proline, hydrogen peroxide, and total phenols content were also performed. In addition, the manipulation of Ag nanoparticles, S. ginsenosidiumtans, and their combination were tested for mercury stress. Here, Ag nanoparticles were formed at 420 nm with a uniform cuboid form and size of 85 nm. Interestingly, the gradual suppression of vegetal growth and photosynthetic pigments by mercury, Ag nanoparticles, and S. ginsenosidiumtans were detected; however, carotenoids and anthocyanins were significantly increased. In addition, proline, hydrogen peroxide, and total phenols content were significantly increased because mercury and S. ginsenosidiumtans enhance this increase. Ag nanoparticles achieve higher levels by the combination. Thus, S. ginsenosidiumtans and Ag nanoparticles could have the plausible ability to relieve and combat mercury’s dangerous effects in fenugreek.

RESPON PERTUMBUHAN BIBIT API-API ( Avicennia marina ) TERHADAP CEKAMAN MERKURI (Hg)

Api-api (Avicennia marina) has potential as the phytoremediation because it can live in a polluted environment. Api-api can be used as biological indicators of the environment that was polluted by heavy metals. The purpose of this research was to measure the effect of growth (the increase in diameter and the number of leaves) of api-api seeds on mercury stress with a dose of 0.5 ml, 2 ml, and 3.5 ml. The research used an experimental method with a completely randomized design, which consists of 4 treatments and 5 repetitions. Each repetition consists of 1 plant, thus the number of seeds that have been observed was 20 plants. The results of the research showed that the mercury solution inhibited the increase in diameter and number of leaves with a confidence level of 95%. Keyword: Avicennia marina, mercury grip, seedling growth.

Mercury contamination imposes structural shift on the microbial community of an agricultural soil

Background The purpose of this study is to use shotgun next-generation sequencing to unravel the microbial community structure of an agricultural soil, decipher the effects of mercury contamination on the structure of the microbial community and the soil physicochemistry and heavy metals content. Results The soil physicochemistry after mercury contamination revealed a shift in soil pH from neutral (6.99 ± 0.001) to acidic (5.96 ± 0.25), a decline in moisture content to < 4 %, and a significant decrease in the concentrations of all the macronutrients and the total organic matter. Significant decrease in all the heavy metals detected in the agricultural soil was also observed in mercury inundated SL3 microcosm. Structural analysis of the metagenomes of SL1 (agricultural soil) and SL3 (mercury-contaminated agricultural soil) using Illumina shotgun next-generation sequencing revealed the loss due to mercury contamination of 54.75 % of the microbial community consisting of an archaeal domain, 11 phyla, 12 classes, 24 orders, 36 families, 59 genera, and 86 species. The dominant phylum, class, genus, and species in SL1 metagenome are Proteobacteria, Bacilli, Staphylococcus, and Sphingobacterium sp. 21; while in SL3 metagenome, Proteobacteria, Alphaproteobacteria, Singulisphaera, and Singulisphaera acidiphila were preponderant. Mercury contamination resulted in a massive upscale in the population of members of the phylum Planctomycetes and the genera Singulisphaera, Brevundimonas, Sanguibacter, Exiguobacterium, Desulfobacca, and Proteus in SL3 metagenome while it causes massive decline in the population of genera Staphylococcus and Brachybacterium. Conclusions This study revealed that mercury contamination of the agricultural soil imposed selective pressure on the members of the microbial community, which negatively impact on their population, alter soil physicochemistry, and enriched sizable numbers of members of the community that are well adapted to mercury stress. It also reveals members of microbial community hitherto not reported to be important in mercury detoxification process.