Diacylglyceryl-N,N,N-trimethylhomoserine-dependent lipid remodeling in a green alga, Chlorella kessleri

Membrane lipid remodeling contributes to the environmental acclimation of plants. In the green lineage, a betaine lipid, diacylglyceryl-N,N,N-trimethylhomoserine (DGTS), is included exclusively among green algae and nonflowering plants. Here, we show that the green alga Chlorella kessleri synthesizes DGTS under phosphorus-deficient conditions through the eukaryotic pathway via the ER. Simultaneously, phosphatidylcholine and phosphatidylethanolamine, which are similar to DGTS in their zwitterionic properties, are almost completely degraded to release 18.1% cellular phosphorus, and to provide diacylglycerol moieties for a part of DGTS synthesis. This lipid remodeling system that substitutes DGTS for extrachloroplast phospholipids to lower the P-quota operates through the expression induction of the BTA1 gene. Investigation of this lipid remodeling system is necessary in a wide range of lower green plants for a comprehensive understanding of their phosphorus deficiency acclimation strategies.

Biosorption of chromium by dry algae Chlorella kessleri

Decontamination of environment according to traditional methods is not only economically inaccessible but also often highly environmentally harmful. It is necessary to apply methods that are environmentally friendly as possible. These methods include bioremediation, which uses organisms able to fight with high concentrations of pollutants to decontaminate the environment. In this study, we observed the biosorption of chromium from the aquatic environment using dried algae Chlorella kessleri. The results of the specific sorption at pH = 4.00 in the chromium model sample had a value of q = 5.9 mg / g, which represented a decrease in the chromium concentration by 74%. The specific sorption in the case of the native chromium sample q after 24 hours reached the highest value (q = 2.74 mg / g) at pH = 4.00. During the experiment, we observed a constant change in the content of photosynthetic pigments in the prepared solutions where it was shown that after 24 h exposure the yield of chlorophyll a was decrease by 95.91% compare to control. In the case of chlorophyll b, the same trend was demonstrated where 91.92% decrease of its content after 24 hours was observed. This type of dried alga has been shown to be a rapid biosorbent, in relatively short time intervals. The results of the study show that in the process of decontamination there was not only the binding of chromium to the cell surface but also its penetration through the cell wall.

Diacylglyceryl-N,N,N-trimethylhomoserine-dependent Lipid Remodeling in a Green Alga, Chlorella Kessleri

Membrane lipid remodeling contributes to environmental 19 acclimation of plants. In a green lineage, a betaine lipid, diacylglyceryl-N,N,N-trimethylhomoserine (DGTS), is included exclusively among green algae and non-flowering plants. Here we show that, a green alga, Chlorella kessleri, reported to exceptionally possess no DGTS, synthesizes it specifically under phosphorus-deficiency conditions through the eukaryotic pathway via the ER. Simultaneously, phosphatidylcholine and phosphatidylethanolamine, which are similar to DGTS in its zwitterionic property, are almost completely degraded to release 18.1% cellular phosphorus, and to provide its diacylglycerol moieties for a part of DGTS synthesis. Above lipid remodeling system that substitutes DGTS for extrachloroplast phospholipids to lower the P-quota operates through expression induction of the gene for BTA1 that is functionally identified as responsible for DGTS synthesis, and those for0 phospholipid breakdown. Investigation of this lipid remodeling is necessary in a widerange of lower green plants for a comprehensive understanding of their phosphorus deficiency acclimation strategies.

Simultaneous Biological Nutrient Removal from Municipal Wastewater and CO2-biofixation using Chlorella kessleri

Growing microalgae in tertiary wastewater offers a prospective avenue to remove and re-use the nutrients N and P simultaneously. Moreover, CO2 fixation via microalgae is a potential and promising approach of capturing and storing CO2. The impacts of various nitrogen to phosphorous ratios on the growth, nutrient removal from municipal wastewater, and the bio-fixation of CO2 using Chlorella kessleri were evaluated in this study. For this purpose, the microalgae was grown in synthetic wastewater, similar in composition to tertiary municipal wastewater, with NP ratios of 2:1, 4:1, 6:1, and 8:1 in batch photobioreactors for13 days. Biomass concentration increases at all NP ratios and the maximum biomass concentration is 606.79 mg/L at the NP ratio of 2:1. Nitrogen removal is more than 95% at all NP ratios except at 8:1, where it is only 72.4%. The removal efficiency of phosphorous is significantly affected by the NP ratio. The maximum phosphorous removal is about 97% for the NP ratio 6:1, whereas the lowest removal efficiency of about 20% is at the NP ratio of 2:1. The maximum CO2 bio-fixation rate of 89.36 mgL− 1d− 1 at the end of the first 7 days of the cultivation period is at the NP ratio of 6:1. In this study, Monod growth kinetic model based on a single substrate factor was used and the experimental findings agree well with the predictions by the model.

IDENTIFIKASI MIKROALGA LAUT DARI TAMBRAUW, PAPUA BARAT

Tambrauw merupakan salah satu Kabupaten di Papua Barat, dikenal sebagai daerah mega-biodiversitas, termasuk mikroalga laut yang memiliki peran penting dalam sistem rantai makanan di perairan. Namun di sisi lain keanekaragaman mikroalga laut di daerah ini masih belum banyak diteliti. Penelitian ini dilakukan untuk mengisolasi dan mengidentifikasi mikroalga laut dari Tambrauw berdasarkan pendekatan morfologi dan molekular. Mikroalga laut diisolasi dari sumber alami di Tambrauw, dimurnikan dan dikultur di bawah kondisi standar. Empat belas kultur mikroalga laut dipilih berdasarkan pertumbuhan, keragaman morfologi dan homogenitas. Karakteristik morfologi diamati dalam kondisi kultur menggunakan mikroskop cahaya dan hubungan filogenetik dari masing-masing strain didefinisikan sesuai dengan analisis sekuen 18S rRNA pada kelompok mikroalga eukariot dan 16S rRNA pada kelompok mikroalga prokariot. Sekuen yang dihasilkan dibandingkan dengan database yang tersedia di situs web NCBI melalui alat bioinformatika BLAST. Hasil penelitian menunjukkan similaritas yang tinggi dengan identitas urutan nukleotida yang dikenal, sebagai Monoraphidium neglectum (99%), Chlorella sorokiniana (99%), Oocystis heteromucosa (99%), Ettlia texensis (99%), Dilabifilum arthopyreniae (98%), Auxenochlorella protothecoides (99%), Trichosarcina polymorpha (98%), Scenedesmus vacuolatus (99%), Chlorella kessleri (99%), Coelastrella oocystiformis (99%), dan Foliisarcina bertiogensis (99%). Studi ini menjadi informasi dasar dalam mengungkap pola keanekaragaman mikroalga, yang sangat penting untuk mendapatkan sumber daya baru genetik untuk kepentingan industri serta studi taksonomi.