A Seagrass‐Based Biorefinery for Generation of Single‐Cell Oils for Biofuel and Oleochemical Production

Abstract

78 million tons of residual seagrass deposits accumulate annually on shorelines worldwide. These represent an untapped feedstock for fermentative single‐cell oil production, targeted at biofuel and oleochemical generation, without affecting the sensitive marine environment or compromising food security. Seven beach‐cast samples of seagrass (related to Z. marina, Z. noltii, S. filiforme, P. australis, P. oceanic, and T. testudinum) were collected from marine ecosystems around the world. A combination of 18S rRNA phylogenetic, structural, and comprehensive biomass analyses of seagrass leaves were applied. The carbohydrate content ranged from 73 to 81 % (w/dwbiomass). Single‐step enzymatic hydrolysis was developed to efficiently release the monomeric sugars contained in seagrasses biomass without any pretreatment. P. oceanica hydrolysate allowed for higher lipid yields (6.8 g L−1) compared to the synthetic minimal medium (5.1 g L−1) in shake flasks, and was subsequently utilized as the sole fermentation medium for oleaginous yeast T. oleaginosus at a technical scale using a fed‐batch bioreactor, which provided 24.5 g L−1 lipids (0.35 g L−1 h−1). Moreover, the sugar/lipid conversion ratio was 0.41 (w/w). Cumulative data indicates that by exploiting only half of the global beach‐cast seagrass, approximately 4 million tons of microbial oils could be generated.

Immobilization of TiO2 Semiconductor Nanoparticles onto Posidonia Oceanica Fibers for Photocatalytic Phenol Degradation

“…The SEM images of POF and POF/TiO2 are shown in Figure 2a-f, respectively. The pure fibers have a long uniform length and a fibrous structure (Figure 2a) as confirmed by other researchers [29][30][31]. After the modification of POF by the sol-gel method, a well-fixed thin film of TiO2 is formed (Figure 2d-f).…”

Microbial lipid production by oleaginous yeasts grown on Scenedesmus obtusiusculus microalgae biomass hydrolysate

“…The use of microbes as a platform for lipid and subsequent biofuel and biodiesel production offers: (1) renewability and potential sustainability, (2) requires less labor and fewer raw materials, (3) is easier to scale up, (4) does not compete with edible-plants for land, (5) generates less waste and (6) is not affected by season or climate [ 46 ]. Recently, the valorization of seagrass and brown macroalgae biomass as feedstock for C. oleaginosus lipid production, in addition to the techno-economic feasibility of the bioprocesses have been conducted in our group [ 2 , 4 ]. In this study, S. obtusiusculus biomass was chosen as feedstock for oily yeast growth, due to its high carbohydrates content 34% (g/g dry biomass weight).…”

“…The ever-increasing energy demand in today's industrial world led to the widespread use of non-renewable fossil fuels such as petroleum. The transition from a society with waste generating, linear production routes to one cyclic valorization path in conjunction with renewable resource management is one of the most demanding technological goals for establishing sustainable bioeconomy [1,2]. This scenario particularly applied renewable energy supply routes that demand a switch from finite fossilto sustainable platform solutions.…”

“…Scenedesmus obtusiusculus A189, a newly isolated member of the Chlorophyta genus, is characterized by high growth rates in fresh and saline media, in addition to high inherent carbohydrate content [35]. Fermentative conversion of various biomass sources into SCOs and subsequent biofuel via oleaginous yeasts has recently received an increasing interest in the scientific and industrial community [2,4]. Specifically, microalgae biomass does not contain recalcitrant lignin, making it suitable for eco-friendly and cost-effective hydrolysis methods [35].…”

“…To that end, efficient hydrolysis of algae biomass could provide a sustainable stream of monomeric hexose and pentose sugars for fermentative growth. However, chemical biomass hydrolysis, which is most commonly applied in industry, tarnishes the eco-friendly aspect of biofuel production [2]. Alternatively, enzymatic hydrolysis efficiently generates sugar-rich fermentation media, yet necessitates thermo-chemical pretreatment steps to break down the lignocellulosic biomass components into monomeric hexose and pentose sugars [36].…”