Harvested Microalgal Biomass from Different Water Treatment Facilities—Its Characteristics and Potential Use as Renewable Sources of Plant Biostimulation

Surface characteristics, physicochemical properties, functional groups, and bioactive compounds of microalgal biomass (MB) samples harvested from various wastewater treatment facilities (WTFs) were investigated to evaluate the reuse feasibility of MB as a potential renewable source of plant biostimulation. Mixtures of the microalgae cells and fine particles (i.e., silt, clay, suspended solids, extracellular organic matter, humus substances, natural organic matter, etc.) were complexed inside MB samples. MB samples harvested and air-dried under natural conditions investigated in this study can have relatively well-preserved cellular morphology as well as chemical substances such as carbohydrates, proteins, and fatty acids based on SEM-EDS analysis. A broad form of the amorphous cellulose rather than a distinct crystalline was observed from FTIR analysis, indicating that the middle spectrum of glucose and starch hydrolysate exist in MB samples. A wide array of chemicals (i.e., Undecane; Heptadecane; Hexadecanoic acid, methyl ester; and Methyl stearate, phenolics, and fatty acids) extracted from MB samples were involved in signaling plant response to abiotic stress, plant growth and biomass with MB samples were greater than those without MB samples. Thus, mixtures of nutrients, minerals and algal biomass in wet and dried MB samples can be beneficially reused as biostimulants in agricultural area after simple processes such as composting, microbial fermentation, and extraction. Further study is warranted to elucidate the effect of useful ingredients in MB harvested from on-site coagulation/flocculation processes on the soil environment as bio-fertilizers.

Carotenoid Production by Rhodosporidium paludigenum Using Cassava Starch Hydrolyzed by Bacillus subtilis as Substrate

Carotenoids are natural pigments with colors ranging from yellow to red that are beneficial for food, cosmetics, and animal feed industries. These pigments can be found in fruits, vegetables, algae, and microorganisms. Among all microorganisms that have been known to produce carotenoids, Rhodosporidium paludigenum is still poorly investigated. Therefore, this study aimed to determine the potential of carotenoid production by R. paludigenum using cassava starch hydrolyzed by Bacillus subtilis as a substrate. The cassava starch for hydrolysis was divided into four concentrations, i.e., 2%, 4%, 6%, and 8% w/v. During the hydrolysis period, the amylase enzyme activity produced by B. subtilis was evaluated. The reducing sugar concentration was then examined to determine the optimum medium for carotenoid production. The highest amylase enzyme activity was produced on the second day in all cassava starch concentrations. However, the highest reducing sugar concentration was discovered in the 6% w/v cassava starch concentration. Thus, a batch submerged fermentation for carotenoid production by R. paludigenum was performed using the hydrolysate as the sole substrate. At the end of the fermentation, the total carotenoid was extracted, and the concentration was determined using spectrophotometry. The total yield of xanthophyll over biomass was higher than that of β-carotene. These findings elucidated the potency of cassava starch hydrolysate obtained from the starch hydrolyzed by B. subtilis, for carotenoid production by the red yeast R. paludigenum.

Sugar substitute: Key facts for their use – A review

A simple, unidirectional schematic depicts the hypothesized pathways by which sugar-sweetened beverage consumption may lead to the development of chronic cardiovascular/cerebrovascular and metabolic diseases, chronic kidney disease, cancer, and gout. Sugar containing dietary foods could be replaced by the use of sugar substitutes available on the market today, both noncaloric and caloric, which have a low or even no cariogenic potential, sugar substitution is an important part of caries prevention and improving the overall health of an individual. The most common sugar substitutes used in Europe today are the caloric sweeteners xylitol, sorbitol, lycasin (hydrogenated starch hydrolysate), maltitol and mannitol and the non-caloric sweeteners accesultame-K, aspartame, cyclamate, and saccharin. They are currently replacing sugar in a wide range of products, such as sweeteners for coffee and tea, confectionery and chewing gum, medicines and soda pop. The need for a safe, palatable, non-nutritive, sweetening agent has prompted new approaches to the development of synthetic sweeteners. One interesting approach is based on the concept called “anatomical compartmentalization,” whereby the molecular weight of a sweet compound is increased to the point where no intestinal absorption occurs, thus eliminating systemic effects. Initial attempts at linking low molecular weight sweeteners to macromolecules have generally yielded products with unsatisfactory taste.