Synthesis, structure and properties of polyhydroxyalkanoates: biological polyesters

Lignocellulosic biomass: a sustainable platform for the production of bio-based chemicals and polymers

Microalgae have recently attracted considerable interest worldwide, due to their extensive application potential in the renewable energy, biopharmaceutical, and nutraceutical industries. Microalgae are renewable, sustainable, and economical sources of biofuels, bioactive medicinal products, and food ingredients. Several microalgae species have been investigated for their potential as value-added products with remarkable pharmacological and biological qualities. As biofuels, they are a perfect substitute to liquid fossil fuels with respect to cost, renewability, and environmental concerns. Microalgae have a significant ability to convert atmospheric CO2 to useful products such as carbohydrates, lipids, and other bioactive metabolites. Although microalgae are feasible sources for bioenergy and biopharmaceuticals in general, some limitations and challenges remain, which must be overcome to upgrade the technology from pilot-phase to industrial level. The most challenging and crucial issues are enhancing microalgae growth rate and product synthesis, dewatering algae culture for biomass production, pretreating biomass, and optimizing the fermentation process in case of algal bioethanol production. The present review describes the advantages of microalgae for the production of biofuels and various bioactive compounds and discusses culturing parameters.

https://link.springer.com/content/pdf/10.1186/s12934-018-0879-x.pdf

The promising future of microalgae: current status, challenges, and optimization of a sustainable and renewable industry for biofuels, feed, and other products

The demand for petroleum dependent chemicals and materials has been increasing despite the dwindling of their fossil resources. As the dead-end of petroleum based industry has started to appear, today's modern society has to implement alternative energy and valuable chemical resources immediately. Owing to the importance of lignocellulosic biomass being the most abundant and bio-renewable biomass on earth, this critical review provides insights into the potential of lignocellulosic biomass as an alternative platform to fossil resources. In this context, over 200 value-added compounds, which can be derived from lignocellulosic biomass by various treatment methods, are presented with their references. Lignocellulosic biomass based polymers and their commercial importance are also reported mainly in the frame of these compounds. This review article aims to draw the map of lignocellulosic biomass derived chemicals and their synthetic polymers, and to reveal the scope of this map in today's modern chemical and polymer industry.

https://www.sbmicrobiologia.org.br/PDF/industrial.pdf

Glycerol: A promising and abundant carbon source for industrial microbiology

Polyhydroxyalkanoates, biopolyesters from renewable resources: Physiological and engineering aspects

As major part of the phytoplankton, microalgae are pivotal for the global food chain. Their exceptional capacity for CO2-fixation illustrates their indispensable significance to sustain earth's ecosystems. Further, they play a still underestimated role in eliminating contaminants from various environments. In addition to ecological benefit, many microalgal species exhibit high nutritional value and, at the same time, generate valued bio-products: Pigments, lipids, bioactive compounds, certain polysaccharides, bio-hydrogen and even biopolyesters with plastic-like properties have the potential for successful market penetration. Three substantial pigment groups, namely chlorophylls, carotenoids, and phycobilins, are essential for light harvesting and CO2 fixation. Those pigments will most likely undergo quick commercial success in “functional food”, cosmetics, aquaculture, pharmaceuticals, or food technology. Due to often high contents of polyunsaturated fatty acids essential for human metabolism, microalgal oils can be commercialized as health food and in the pharmaceutical and therapeutic field, creating much higher value than by converting them to biofuel. Finally, algal biomass remaining as residue after product recovery can be used as forage, biogas feedstock or biofertilizer. This utilization is needed for balancing the material- and energy cycles of the entire process. Thus, technology platforms following the principles of bio-refineries shall be established to enable the design of sustainable and economically feasible production of marketable microalgal products.

Microalgae as versatile cellular factories for valued products

Producing microbial polyhydroxyalkanoate (PHA) biopolyesters in a sustainable manner

Production of polyhydroxyalkanoates from agricultural waste and surplus materials.

Three different microbial wild-type strains are compared with respect to their potential as industrial scale polyhydroxyalkanoate (PHA) producers from the feed stock whey lactose. The halophilic archaeon Haloferax mediterranei as well as two eubacterial strains (Pseudomonas hydrogenovora and Hydrogenophaga pseudoflava) are investigated. H. mediterranei accumulated 50 wt.-% of poly-3-(hydroxybutyrate-co-8%-hydroxyvalerate) from hydrolyzed whey without addition of 3-hydroxyvalerate (3HV) precursors (specific productivity q(p): 9.1 mg x g(-1) x h(-1)). Using P. hydrogenovora, the final percentage of poly-3-hydroxybutyrate (PHB) amounted to 12 wt.-% (q(p): 2.9 mg x g(-1) x h(-1)). With H. pseudoflava, it was possible to reach 40 wt.-% P-3(HB-co-5%-HV) on non-hydrolyzed whey lactose plus addition of valeric acid as 3HV precursor (q(p): 12.5 mg x g(-1) x h(-1)). A detailed characterization of the isolated biopolyesters and an evaluation with regard to the economic feasibility completes the study.

Gerhart Braunegg

Papers

Polyhydroxyalkanoates, biopolyesters from renewable resources: Physiological and engineering aspects

Microalgae as versatile cellular factories for valued products

Producing microbial polyhydroxyalkanoate (PHA) biopolyesters in a sustainable manner

Production of polyhydroxyalkanoates from agricultural waste and surplus materials.

Potential of various archae- and eubacterial strains as industrial polyhydroxyalkanoate producers from whey.