Study of Marine Sand-Dwelling Dinoflagellate With Four New Records From the Central South Coast of Viet Nam

In this study, marine sand samples were collected from the shallow intertidal zone of Nha Trang bay, Viet Nam. Taxonomic observations were conducted for the sanddwelling dinoflagellates using light, epifluorescent and scanning electron microscopy. Morphology characterizations of the four species namely, Amphidiniopsis hexagona, Thecadinium pseudokofoidii, Amphidinium herdmanii and Fukuyoa ruetzleri have been reported as new records for Vietnamese coastal waters. The genus Amphidiniopsis and Thecadinium are a new addition to the dinoflagellates flora of Viet Nam. Taxomomic descriptions and photographs of these species have been provided. Bangladesh J. Plant Taxon. 28(2): 367-378, 2021 (December)

Pseudomarimonas arenosa gen. nov., sp. nov. isolated from marine sand

A novel Gram-negative, aerobic, non-motile, rod-shaped, bacterial strain (CAU 1598T) was isolated from marine sand. Strain CAU 1598T grew well at 30 °C, pH 6.5–7.0 and with 3 % NaCl (w/v). Phylogeny results based on 16S rRNA gene sequencing indicated that the identified strain had the highest similarity (94.3%) to Pseudoxanthomonas putridarboris , indicating that strain CAU 1598T belongs to the family Xanthomonadaceae . Further, the fatty acid profile of the strain was primarily composed of C16:0, iso-C15 : 0, iso-C16 : 0, summed feature 3 (consisting of C16 : 1 ω7c/iso-C15 : 0 2-OH) and summed feature 9 (consisting of iso-C17 : 1 ω9c and/or C16 : 0 10-methyl), with ubiquinone-8 as the major isoprenoid quinone. The polar lipid profile included diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphoglycolipid, an unidentified aminolipid and an unidentified lipid. The G+C content of the bacterial genome was 62.6 mol% and its 5.4 Mb length encompassed 144 contigs and 4236 protein-coding genes. These phenotypic, chemotaxonomic and phylogenetic data indicate that CAU 1598T belongs to a new genus and species, for which the name Pseudomarimonas arenosa gen. nov., sp. nov. is proposed. The type strain is CAU 1598T (=KCTC 82406T=MCCC 1K05673T).

Amphidinium stirisquamtum sp. nov. (Dinophyceae), a new marine sand-dwelling dinoflagellate with a novel type of body scale

Amphidinium species are amongst the most abundant benthic dinoflagellates in marine intertidal sandy ecosystems. Some of them produce a variety of bioactive compounds that have both harmful effects and pharmaceutical potential. In this study, Amphidinium cells were isolated from intertidal sand collected from the East China Sea. The two strains established were subjected to detailed examination by light, and scanning and transmission electron microscopy. The vegetative cells had a minute, irregular, and triangular-shaped epicone deflected to the left, thus fitting the description of Amphidinium sensu stricto. These strains are distinguished from other Amphidinium species by combination characteristics: (1) longitudinal flagellum inserted in the lower third of the cell; (2) icicle-shaped scales, 276 ± 17 nm in length, on the cell body surface; (3) asymmetrical hypocone with the left side longer than the right; and (4) presence of immotile cells. Therefore, they are described here as Amphidinium stirisquamtum sp. nov. The molecular tree inferred from small subunit rRNA, large subunit rRNA, and internal transcribed spacer-5.8S sequences revealed that A. stirisquamtum is grouped together with the type species of Amphidinium, A. operculatum, in a fully supported clade, but is distantly related to other Amphidinium species bearing body scale. Live A. stirisquamtum cells greatly affected the survival of rotifers and brine shrimp, their primary grazers, making them more susceptible to predation by the higher tropic level consumers in the food web. This will increase the risk of introducing toxicity, and consequently, the bioaccumulation of toxins through marine food webs.

Evaluation of modulus of elasticity for eco-friendly concrete made with seawater and marine sand

The ultimate aim of this study is to use experimental work for evaluating the modulus of elasticity (MOE) of Geopolymer concrete (GPC) using marine sand as fine aggregate and seawater for the mix. Four different groups of concrete mixtures, namely CP1a, CP1b, CP2a, CP2b were identified. While the CP1a mix was prepared using GPC with marine sand and seawater, the CP1b was made by adding sodium sulfate (Na2SO4) into the CP1a mix. The same procedure was applied for CP2a and CP2b mixtures; however, instead of using GPC, Portland Cement was used as the binder for the CP2 group (OPC). A total of 12 test samples were cast and tested to determine the development of MOE of GPC and OPC over time. The MOE of concrete was measured at 3, 7, 28, 60, and 120 days. Experimental results were then compared to the MOE obtained using the empirical equation from ACI 318 - 2008. It was found that the experimental MOE of both OPC and GPC specimens was higher than the estimated MOE values from ACI standards. The added sodium sulfate yielded a significant effect on the MOE of OPC but produced a minimal influence on the MOE of GPC.

Agromyces mariniharenae sp. nov., a novel indole-acetic acid producing actinobacterium isolated from marine sand

A Gram-positive, aerobic, heterotrophic, non-endospore-forming, rod-shaped and indole-acetic acid-producing strain, designated NEAU-184T, was isolated from marine sand collected in Sanya, PR China, and its taxonomic position was investigated using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequence data indicated that strain NEAU-184T should be assigned to the genus Agromyces and formed a distinct branch with its closest neighbour, Agromyces iriomotensis NBRC 106452T (99.1 %). 2,4-Diaminobutyric acid, d-alanine, d-glutamic acid and glycine were detected in cell-wall hydrolysate and glucose, rhamnose and xylose were detected in whole-cell hydrolysate. The polar lipids were found to contain diphosphatidylglycerol, glycolipid, phosphatidylglycerol and two unidentified lipids. The major menaquinone was MK-12 and the minor menaquinones were MK-13 and MK-11. The predominant fatty acids were anteiso-C17 : 0, anteiso-C15 : 0 and iso-C16 : 0. The DNA G+C content was 71.5 mol%. Furthermore, the strain could be clearly distinguished from its closely related type strains by the combination of DNA–DNA hybridization results and some phenotypic characteristics. Meanwhile, the strain has the ability to produce indole-acetic acid (0.334mg ml−1). Therefore, strain NEAU-184T represents a novel species of the genus Agromyces , for which the name Agromyces mariniharenae sp. nov. is proposed, with strain NEAU-184T (=CGMCC 4.7505T=JCM 32546T) as the type strain.