Large-scale screening of natural genetic resource in the hydrocarbon-producing microalga Botrycoccus braunii identified novel fast-growing strains

Abstract

Algal biofuel research aims to make a renewable, carbon–neutral biofuel by using oil-producing microalgae. The freshwater microalga Botryococcus braunii has received much attention due to its ability to accumulate large amounts of petroleum-like hydrocarbons but suffers from slow growth. We performed a large-scale screening of fast-growing strains with 180 strains isolated from 22 ponds located in a wide geographic range from the tropics to cool-temperate. A fast-growing strain, Showa, which recorded the highest productivities of algal hydrocarbons to date, was used as a benchmark. The initial screening was performed by monitoring optical densities in glass tubes and identified 9 wild strains with faster or equivalent growth rates to Showa. The biomass-based assessments showed that biomass and hydrocarbon productivities of these strains were 12–37% and 11–88% higher than that of Showa, respectively. One strain, OIT-678 established a new record of the fastest growth rate in the race B strains with a doubling time of 1.2 days. The OIT-678 had 36% higher biomass productivity, 34% higher hydrocarbon productivity, and 20% higher biomass density than Showa at the same cultivation conditions, suggesting the potential of the new strain to break the record for the highest productivities of hydrocarbons.

Microbial genetic engineering approach to replace shark livering for squalene

“…The oleaginous yeast Yarrowia lipolytica [36], the non-oleaginous yeast Saccharomyces cerevisiae [37], and the bacterium Escherichia coli [38] have been genetically engineered and exploited extensively for the production of squalene. Although only a few strains of microalgae and cyanobacteria produce squalene, the green microalga Botryococcus braunii has been targeted for hydrocarbon production [39,40]. B. braunii strain Abt02 was reported to contain 43.75% hydrocarbons based on dry biomass, of which 87.54% were squalene and its derivatives [41].…”

Development of sustainable bioproducts from microalgae biomass: Current status and future perspectives

“…Microalgae is an appropriate answer to the aforementioned challenges because of its major advantages. It has a doubling time on average of 26 h, high productivity, and the capacity to withstand food and feed competition (Kawamura et al 2021). Microalgae is ecologically susceptible to manipulation, grows in non-arable land, requires exceptionally small spaces for farming, harnesses greenhouse gases for its growth, and is able to grow in wastewater with minimal nutrients (Odjadjare et al 2015).…”

Application of Analytic Hierarchy Process in the Selection of Botryococcus braunii Cultivation Technology for Bio-crude Oil Production

“…B. braunii has also been considered a slow-growing alga with a generation time of 7 days in nature [16], while the Showa strain shows that it has a fast growth rate of 1.4 days [17]. Recently, it was discovered that there are 9 fast-growing strains with faster growth rates or similar to the Showa strain [18]. A previous report also stated that some of the properties of B. braunii crude oil are comparable to diesel oil, except for its higher kinematic viscosity [19].…”