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Tetrodotoxin analogues (TTXs) used in research and development were originated from biological sources for the last decades. Among TTXs‐bearing aquatic animals, horseshoe crab Carcinoscorpius rotundicauda from Vietnam's Coast was reported to contain a high level of TTXs, indicating a promising source for extraction and purification of TTXs. In this work, horseshoe crab C. rotundicauda collected from Can Gio Coast, Vietnam was used for TTX extraction using homogenization‐assisted method with acetic acid solvent. The extraction process was analysed and optimized by single‐factor investigation and response surface methodology (RSM). Single‐factor investigation pointed out that the optimal conditions for TTX recovery yield from C. rotundicauda's soft tissues were homogenization time of 20 min, acetic acid concentration of 1.0%, solvent/matrix ratio of 4 mL/g, extraction temperature of 70°C, extraction time of 30 min and number of extraction of two times. The most significant factors including acetic acid concentration, solvent/matrix ratio and extraction temperature were utilized for constructing the RSM model to predict TTX recovery yield. The maximal TTX recovery yield predicted from RSM model was 97.3% under solvent/matrix ratio of 4 mL/g, extraction temperature of 70°C and acetic acid concentration of 1% (v/v). The RSM model displayed a high stability and precision for prediction of TTX recovery yield from experiments of 1–10 kg C. rotundicauda's soft tissues/batch extractions producing low errors (−1.95% to 1.85%). TTXs in C. rotundicauda's soft tissues were elucidated by HPLC‐MS/MS, revealing the presence of three analogues TTX, 4epi‐TTX and Anh‐TTX with their contents of 43.02, 22.54 and 45.07 μg/g, respectively. [ABSTRACT FROM AUTHOR]

BACKGROUND Full demonstrations of the production of microalgal biodiesel from conversion to purification have been reported only rarely in the literature. This study was aimed at developing a mini production line consisting of sequential conversion, extraction and purification of biodiesel from Scenedesmus acuminatus S4 grown in domestic wastewater. RESULTS: The data showed that the separated conversion‐extraction (SCE) produced biodiesel with high yield (99.9%) and purity (87.5%) at 200 g L–1 biomass loading, 5% H2SO4/methanol (v/v) catalyst loading, 100 °C reaction temperature and 200 rpm stirring rate, in a 1 h conversion reaction, followed by extraction with hexane (10 mL:1 g dry cell weight) by mixing for 10 min (200 rpm) at 25 °C. The integrated conversion‐extraction (ICE) performed by simultaneous addition of hexane to the biomass and the catalytic solution mixture under the optimized conditions, achieved biodiesel yield and purity of 91.9% and 81.4%, respectively. Crude biodiesel was purified by 40% (w/v) adsorbents [Magnesol and D‐sol® (D60)]/crude biodiesel achieving >95% fatty acid methyl esters (FAME) purity, which is superior to the results in the literature and equivalent to fuel grade standard. CONCLUSIONS: Fuel grade biodiesel was successfully produced from S. acuminatus S4 via sequential steps of direct conversion, extraction and purification. The conversion step can be performed via SCE or ICE followed by extraction to obtain crude biodiesel (99% yield and 87.5% purity), whereas the purification step was implemented by dry‐washing with Magnesol or D‐sol® (D60) to >95% FAME. The current production line has technical merits that need to be further optimized for large‐scale application. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Microalgae have been reported to produce endogenous phytohormones including auxins, gibberellins, cytokinins, brassinosteroids, and abscisic acid. Methanol residual released from microalgal lipid extraction usually contains a variety of bioactive compounds including the phytohormones; however, they are poorly characterized and used for other applications. This study aimed at investigating auxin, gibberellin, and cytokinin production of C. sorokiniana TH01 under phototrophic and mixtrophic cultivations. Moreover, endogenous auxins, gibberellins, and cytokinins in methanol residual obtained from the algal lipid extraction were characterized using HPLC-ESI-MS/MS toward application for crop and biorefinery research. Data showed that endogenous indole-3-acetic acid (IAA), 3-indolepropionic acid (IPA), gibberellin A4 (GA4), and gibberellin A7 (GA7) were detected in C. sorokiniana TH01 biomass. Under the phototrophic mode, total auxin and GA levels were reduced to 0.98 and 9.65 μg/g DW under salt stress (20 g NaCl/L) from 3.59 to 24.71 μg/g DW, respectively, measured for the control. Similarly, total auxins and GAs were also decreased to 0.56 and 2.86 μg/g DW, respectively, under mixtrophic growth with 6 g glucose/L. Total auxins and GAs determined in the water algal extract were 1062.7 and 2000.1 μg/L, respectively. Treatment with higher 40% (v/v) of the algal extract triggered earlier seed germination of rice and tomato plants in 2 and 1 days, respectively. Our new findings in capability of C. sorokiniana TH01 in endogenous phytohormone production contain fundamental merits for further optimization of the algal production (i.e., cultivation modes, conditions, lipids, biomass productivity, and hormone levels) to be used for biorefinery. [ABSTRACT FROM AUTHOR]