Microalgae are well-recognized by many researchers working on bioenergy resources due to its capability to produce high amounts of lipids as biodiesel precursors. Diatoms as a group of microalgae that specifically categorized by their silica valve could be more attractive to the researchers because in addition to high-lipid content, their silica features can be also utilized for wider applications, or used for diatoms bioproduct purification. Identification of some diatom species, such as the diatom genus Chaetoceros, as an initial step in diatom studies were difficult to accurately perform because of the unique morphology of silica frustules. Meanwhile, some candidate universal genetic markers of microalgae could also be used for the identification of diatoms with brittle frustules. In this research, we aimed to identify isolate CBO of tropical marine Chaetoceros CBO strain using morphological and genetic approaches. The isolate CBO of Chaetoceros sp. CBO was successfully obtained from sea region of Bokor Island, Kepulauan Seribu, Jakarta, and cultivated in our laboratory as culture stock for further use. Better resolution of the Chaetoceros CBO identification until species level was shown by genetic analysis toward two proposed gene markers for microalgae (rbcL-3P and V4 region of 18S rDNA) rather than by morphological. Specific DNA region for this specimen was found in V4 region of 18S rDNA genetic marker that could be recognized by MspA1I restriction enzyme. Hence, the RFLP (restriction fragment length polymorphism) method could be also used as an initial diagnostic tool for identification of this tropical marine Chaetoceros dayaensis CBO and for stock culture labelling purposes.

The Valence Shell Electron Pair Repulsion (VSEPR) is an essential topic for high school student’s fundamental understanding of 3D shapes of chemical compounds. Due to the spatial aspect of the topic, the students were forced to imagine the geometry of the molecule by predicting the free or bonded electron pair repulsion. Suitable learning media to accommodate those features should be precisely selected to help students properly understand the geometry of the molecule based on the VSEPR topic. This study compared the significant difference in the application of two media of animation video and interactive simulation toward the control and experimental groups, respectively, to enhance conceptual mastery of the VSEPR topic. This study was a statistical quasi-experiment study with two classes of control (animation video) and experimental (interactive simulation) groups. The results of the significant difference test of the groups showed that the distribution of the experimental and control groups was not normal (significantly different) and normal (not significantly different), respectively. Analysis results using Mann-Whitney for the non-parametric free two samples comparative test with a 95% confidence level showed that the application of virtual simulation on the experimental group impacted more in improving the conceptual mastery of the VSEPR topic. Furthermore, there was an identified significant improvement in sub-concepts of the VSEPR topic in binding pair, molecular shape, and electron repulsion. These findings could support the teachers in designing lesson plans for students to master the VSEPR topic.

Marine microalgae with their diverse biomolecule contents could be used as potential sources of food, cosmetics, and pharmaceutical ingredients. In accordance with regulations in some countries and to competitively engage huge numbers of consumers, microalgae-based products should be properly manufactured using non-animal-derived materials. As a cultivable microorganism using a scalable bioreactor technique, consideration of the origin of the material used in the upstream process of marine microalgae was inevitable. Currently, the material origin of chemical contents within common artificial microalgal seawater medium had not been evaluated. This article evaluated Guillard f/2 and Walne medium as common artificial microalgal nutrients used in marine microalgal bioprocess-related activities. The risk assessment results showed that the largest portion of Guillard f/2 and Walne media were inorganic salts considered as low, while the remaining biochemical contents of vitamins were categorized as high risk due to their relatively complex chemical synthesis and enzymatic stages during the manufacturing process. As a suggestion, several plant-based bioproducts were proposed as alternative sources to substitute related biochemical actions to fulfill non-animal-origin aspects in the initial stages of the bioprocessing of marine microalgal-based products.