Bacterial communities in the rhizosphere of Phragmites australis from an oil-polluted wetland

Although Phragmites australis is commonly planted in constructed wetlands, very little is known about its roots-associated bacterial communities, especially in wetlands used for the remediation of oil produced waters. Here, we describe the bacterial diversity, using molecular (illumina MiSeq sequencing) and cultivation techniques, in the rhizosphere soils of P. australis from an oil-polluted wetland in Oman. The obtained isolates were tested for their plant-growth promoting properties. Most sequences belonged to Proteobacteria, Bacteriodetes and Firmicutes. Sequences of potential hydrocarbon-degrading bacteria (e.g. Ochrobactrum, and Pseudomonas) were frequently encountered. All soils contained sequences of known sulfur-oxidizing (e.g. Thiobacillus, Thiofaba, Rhodobacter and Sulfurovum) and sulfate-reducing bacteria, although the latter group made up only 0.1% to 3% of total sequences. The obtained isolates from the rhizosphere soils were phylogenetically affiliated to Serratia, Acinetobacter, Xenorhabdus, Escherichia and Salmonella. All strains were able to solubilize phosphate and about half were capable of producing organic acids and 1-aminocyclopropane-1-carboxylate (ACC) deaminase. Around 42% of the strains had the ability to produce indole acetic acid and siderophores. We conclude that the rhizosphere soils of P. australis in oil polluted wetlands harbor diverse bacterial communities that could enhance the wetland performance through hydrocarbon degradation, nutrient cycling and supporting plant growth.     

New α-Glucosidase Inhibitory Triterpenic Acid from Marine Macro Green Alga Codium dwarkense Boergs

The marine ecosystem has been a key resource for secondary metabolites with promising biological roles. In the current study, bioassay-guided phytochemical investigations were carried out to assess the presence of enzyme inhibitory chemical constituents from the methanolic extract of marine green alga—Codium dwarkense. The bioactive fractions were further subjected to chromatographic separations, which resulted in the isolation of a new triterpenic acid; dwarkenoic acid (1) and the known sterols; androst-5-en-3β-ol (2), stigmasta-5,25-dien-3β,7α-diol (3), ergosta-5,25-dien-3β-ol (4), 7-hydroxystigmasta-4,25-dien-3-one-7-O-β-d-fucopyranoside (5), 7-hydroxystigmasta-4,25-dien-3-one (6), and stigmasta-5,25-dien-3β-ol (7). The structure elucidation of the new compound was carried out by combined mass spectrometry and 1D (¹H and ¹³C) and 2D (HSQC, HMBC, COSY, and NOESY) NMR spectroscopic data. The sub-fractions and pure constituents were assayed for enzymatic inhibition of alpha-glucosidase. Compound 1 showed significant inhibition at all concentrations. Compounds 2, 3, 5, and 7 exhibited a dose-dependent response, whereas compounds 4–6 showed moderate inhibition. Utilizing such marine-derived biological resources could lead to drug discoveries related to anti-diabetics.