Characteristics of tropical freshwater microalgae Micractinium conductrix, Monoraphidium sp. and Choricystis parasitica, and their potency as biodiesel feedstock

Abstract

The depletion of fossil fuel reserves requires advance anticipation through the search for alternative energy from renewable natural resources. Microalgae have been known as potential organisms for biodiesel feedstock. However, in order to be developed on a large scale, microalgae must have superior traits so that further development becomes more comfortable and cheaper. Tropical lakes are a source of superior microalgae adapted to moderate conditions which can later save operational costs in large-scale production. Situ Gintung and Situ Pamulang are the two largest lakes in South Tangerang, Indonesia and are potential sources of microalgae. Four microalgae isolates from both lakes have been identified, and their potential has been examined. Within an observation period of 18 days, they showed similar growth patterns reaching more than 108 cells mL−1 on day 14 and were able to resist increasing pH. The microalgae were identified through morphological observations and the sequencing of 23S rRNA genes with phylogenetic analysis. Each strain has a positive quality. Isolate G4-3, which was identified as Micractinium conductrix, and P5-4, which was identified as Monoraphidium sp., yielded biomass that exceeded 1.2 g L−1 with lipid content exceeding 60%. Likewise, G4-9, which was also identified as Micractinium conductrix, and P2-15, which was identified as Choricystis parasitica, have lipid content which accounted for 89.10% and 57.48%, respectively; although their biomass was lower. The percentage of fatty acid methyl esters of the four microalgae achieved >60–80%; thus, meeting the standard of biodiesel properties. Therefore, the microalgae isolates have great potential for being developed as biodiesel feedstock.

Treatment of a slaughterhouse wastewater by anoxic–aerobic biological reactors followed by UV‐C disinfection and microalgae bioremediation

“…Recently, the use of microalgae appears as a sustainable and cost‐effective solution as it effectively converts CO 2 and nutrients into biomass that can be transformed into products with high added value (Almomani et al, 2019). For instance, biodiesel production from microalgae has proven to be feasible (Pikoli, Sari, Solihat, & Permana, 2019), and the process become even more sustainable when nutrients from wastewaters are used to support the growth of microalgae, which may coexist with bacteria in the biological treatment system (Aketo et al, 2020; Zhou et al, 2020). This approach is especially relevant in the context of circular economy, maximizing the recovery of resources from wastewaters.…”

Microalgae as Raw Materials for Aquafeeds: Growth Kinetics and Improvement Strategies of Polyunsaturated Fatty Acids Production

“…Many microalgae can accumulate lipids, making up between 20 and 50% of their dry weight [26,[53][54][55]. Nevertheless, when microalgae are subjected to stress, they can produce up to 85%, depending on the growth conditions and the producer species [56][57][58][59][60][61].…”

“…Microalgae as primary producers of ω -3 PUFA in marine ecosystems have demonstrated the potential to reduce dependence on conventional raw materials for aquaculture diets [ 45 , 49 – 52 ]. Many microalgae can accumulate lipids, making up between 20 and 50% of their dry weight [ 26 , 53 – 55 ]. Nevertheless, when microalgae are subjected to stress, they can produce up to 85%, depending on the growth conditions and the producer species [ 56 – 61 ].…”

“…The implementation of large-scale production systems has varied, being limited to microalga products of strong commercial interest [ 138 ]. Certain strains of microalgae present different requirements in terms of nutrient intake and supply, as well as in their environmental and culture conditions [ 53 ]. Nevertheless, it is recognised that investigations are in the initial stages, and there is still a long way to go [ 139 ].…”

Natural freshwater microalgae biofilm as a tool for the clean-up of water resulting from mining activities

“…The microorganisms developing freshwater micro algae biofilm are physiologically different from other planktonic cells of a similar organism floating in a freshwater environment (Pikoli et al 2019). Natural biofilm consists of different types of microorganisms which could either feed autotrophically or heterotrophically.…”