Microalgae as sustainable food and feed sources for animals and humans - Biotechnological and environmental aspects.

Offering a potential solution for global food security and mitigating environmental issues caused by the expansion of land-based food production, the carbon-hunger and nutrient-rich microalgae emerged as a sustainable food source for both humans and animals. Other than as an alternative source for protein, microalgae offer its most valuable nutrients, omega-3 and 6 long-chain polyunsaturated fatty acids where the content can compete with that of marine fish with lower chemicals contamination and higher purity. Furthermore, the colorful pigments of microalgae can act as antioxidants together with many other health-improving properties as well as a natural colorant. In addition, the supplementation of algae as animal feed provides plentiful benefits, such as improved growth and body weight, reduced feed intake, enhanced immune response and durability towards illness, antibacterial and antiviral action as well as enrichment of livestock products with bioactive compounds. The significant breakthrough in algal biotechnology has made algae a powerful "cell factory" for food production and lead to the rapid growth of the algal bioeconomy in the food and feed industry. The first overview of this review was to present the general of microalgae and its potential capability. Subsequently, the nutritional compositions of microalgae were discussed together with its applications in human foods and animal feeds, followed by the exploration of their economic feasibility and sustainability as well as market trends. Lastly, both challenges and future perspectives were also discussed.

Current advances in biological swine wastewater treatment using microalgae-based processes.

There is an exponential increase in swine farms around the world to meet the increasing demand for proteins, resulting in a significant amount of swine/piggery wastewater. The wastewater produced in swine farms are rich in ammonia with high eutrophication potential and negative environmental impacts. Safe methods for treatment and disposal of swine wastewater have attracted increased research attention in the recent decades. Conventional wastewater treatment methods are limited by the high ammonia content and chemical/biological oxygen demand of swine wastewater. Recently, microalgal cultivation is being proposed for the phytoremediation of swine wastewater. Microalgae are tolerant to high ammonia levels seen in swine wastewater and they also ensure phosphorus removal simultaneously. This review first gives a brief overview on the conventional methods used for swine wastewater treatment. Microalgae-based processes for the clean-up of swine wastewater are discussed in detail, with their potential advantages and limitations. Future research perspectives are also presented.

Microalgae-based biorefinery--from biofuels to natural products.

The potential for biodiesel production from microalgal lipids and for CO2 mitigation due to photoautotrophic growth of microalgae have recently been recognized. Microalgae biomass also has other valuable components, including carbohydrates, long chain fatty acids, pigments and proteins. The microalgae-based carbohydrates consist mainly of cellulose and starch without lignin; thus they can be ready carbon source for the fermentation industry. Some microalgae can produce long chain fatty acids (such as DHA and EPA) as valuable health food supplements. In addition, microalgal pigments and proteins have considerable potential for many medical applications. This review article presents comprehensive information on the current state of these commercial applications, as well as the utilization and characteristics of the microalgal components, in addition to the key factors and challenges that should be addressed during the production of these materials, and thus provides a useful report that can aid the development of an efficient microalgae-based biorefinery process.

Lactic acid production directly from starch in a starch-controlled fed-batch operation using Lactobacillus amylophilus.

Based on the batch results, we constructed a simplified simultaneous saccharification and fermentation (SSF) model for the simulation of lactic acid production directly from unhydrolyzed potato starch using Lactobacillus amylophilus. The results of batch operation at different initial starch concentrations (20, 40 and 60 g/l) indicated that a higher initial starch concentration would lead to a slightly lower productivity, but would largely decrease the yield. Among that, the batch with 20 g/l of initial starch had the maximum productivity and the maximum yield, which would be 0.31 g/(l h) and 98% (g/g), respectively. In view of increasing the productivity and the final lactic acid concentration, a starch-controlled fed-batch operation with 20 g/l of initial starch was performed. It showed the fed-batch operation with starch controlled at 8 ± 1 g/l by adjusting the starch-feeding rate led to the maximum productivity of 0.75 g/(l h) and the yield of 69%.