Effects of culture medium salinity on the hydrocarbon extractability, growth and morphology of Botryococcus braunii

A geochemical investigation of the free and carbonate-bound organic matter in the clay-sized fraction of argillaceous source rocks and its significance for biogenic interpretation

“…Thus, it could be concluded that the molecular differences of the CM-bound fractions between the Es 3 and Es 4 CFs could be ascribed to the same reason responsible for the distinction between their free counterparts, which is the differences in developed algal species as a consequence of adaptation to different sedimentary environments (Pang et al 2005;Zhang et al 2009;Li et al 2017a), as evidenced by the source-related biomarkers identified in the free and CM-bound fractions of the Es 3 and Es 4 CFs. Although Botryococcus braunii, indicated by the BSs in the CM-bound fractions, could thrive in both fresh and saline lacustrine environments, recent research found out that Botryococcus species developed in aquatic environments with medium salinity exhibit better hydrocarbon generation potential (Grice et al 1998;Furuhashi et al 2016), which is consistent with our research results and the exploration practice, that compared to the Es 3 source rocks, the Es 4 was a more significant contributor to the hydrocarbon production of the Dongying Sag.…”

In situ extraction (milking) of the two promising Botryococcus braunii strains Showa and Bot22 under optimized extraction time

“…For example, the cultivation conditions of the preculture could have a lasting influence on the behavior of a microalgal culture under investigation (Kojima and Zhang 1999). Furthermore, small changes in culture conditions such as nutrient concentration could lead to morphological changes in B. braunii colonies (Tanoi et al 2014;Furuhashi et al 2016a), which in turn affects the concentration of extracellular hydrocarbons. During the experiments in this study, great care was taken to keep cultivation and extraction parameters constant.…”

Improving the Energy Balance of Hydrocarbon Production Using an Inclined Solid–Liquid Separator with a Wedge-Wire Screen and Easy Hydrocarbon Recovery from Botryococcus braunii

“…braunii race B (Showa strain) was cultured in a 10 L culture bag aerated with 1% CO 2 at 25 • C under illumination (100 µmol m −2 s −1 ) with a 12 h light-dark cycle for 30 days. Two types of culture media were used: a modified Chu13 medium as the freshwater medium (FM) and a brackish medium (BM) with a salinity of 3 g L −1 , which was prepared by diluting commercial artificial seawater (Daigo's Artificial Seawater SP for Marine Microalgae Medium, Wako Pure Chemical Industries, Japan; total salinity, 36 g L −1 ) [22]. In our previous study, we found that this salinity did not inhibit algal growth or the hydrocarbon production rate (0.031 g-hydrocarbons L −1 d −1 in both the FM and the BM) [22].…”

“…Various pretreatments, such as drying [19], homogenization [20], and pre-heating [21], have been reported to improve hydrocarbon recovery using n-hexane, but these methods also require thermal or electrical energy as an input for treating algal slurries. Previously, we reported that the hydrocarbon recovery rate could be improved from B. braunii cultured in a brackish medium (BM) with a salinity of 3 g L −1 without growth inhibition [22]; this improvement was attributed to a shortening in the colony sheath and low fibrilliform density via a shift in algal metabolism from the biosynthesis of the colony sheath consisting of polysaccharides that surround the algal colonies to produce osmolytes of disaccharides and obtain salt tolerance [18]. When the salinity in the medium rises above 3 g L −1 , the hydrocarbon recovery rate is improved more but the growth is inhibited.…”

“…Moreover, algal culture in a BM increased the colony size, with the median particle diameter of colonies increasing from ≈60 µm in a freshwater medium (FM) to over 200 µm in a BM [22]. Increases in the colony size of B. braunii are achieved using a high light intensity [25] or in the presence of 40 mM glucose [26].…”