Biochemical Characterization of Lipid-Extracted Microalgal Biomass Residues

Massive interests to microalgal biodiesel are obvious to date, due to the promising prospect of microalgae as biodiesel feedstock. Nevertheless, based on the result of energy analyses and life- cycle assessments, microalgal biodiesel production has consumed large amount of energy and it has not been cost effective yet. Therefore, utilization of lipid-extracted microalgal biomass residues (LMBRs), one kind of residues produced after lipid extraction in biodiesel production should be effectively investigated. This work emphasizes on the overview of researches related to the biochemical characterization of LMBRs. The LMBRs of Dunaliella tertiolecta (UTEX LB  999) consisted of total carbohydrates of 82.0%, proteins of 13.4%, and ash of 4.5% (w/w in dry mass). Meanwhile, D. tertiolecta LB 999 LMBRs contained carbohydrate of 60%, and its saccharification  yield was 42% based on LMBRs mass. Moreover, the biochemical composition of Haematococcus pluvialis LMBRs were crude fiber (9.6%), crude protein (40.3%), and crude lipid (0.9%) while Scenedesmus sp. LMBRs contained carbohydrate (24.7%), protein (32.4%), lipid (6.5%) and ash (10.0%). Keywords: microalgal, biodiesel, LCA, LMBRs, characterization, EPS, saccharificatio

Kinetic characteristics of \u3b2-cyclodextrin production by cyclodextrin glycosyltransferase from newly isolated Bacillus sp. C26

The kinetic characteristics of \u3b2-cyclodextrin production by a cyclodextrin glycosyltransferase (CGTase) produced by Bacillus sp. C26, a new isolate from a soil sample was investigated. Considering highest yield and initial production rate of \u3b2-cyclodextrin, among the starches examined, soluble starch, tapioca starch, sago starch, corn starch and rice starch, tapioca starch was the best substrate for this CGTase. The optimum temperature for tapioca starch gelatinization prior to its use as a substrate for \u3b2-cyclodextrin production was 65\ub0C. The yield and initial production rate of \u3b2-cyclodextrin increased with increasing starch concentration up to 6% and an enzyme concentration up to 48 U/g-starch. The kinetic parameters of Vmax and Km of \u3b2-cyclodextrin production from tapioca starch by CGTase were 1.59 mg/mL/h and 22.3 mg/mL, respectively. Considering high initial production rate and high yield of \u3b2-cyclodextrin, the optimum reaction temperature was at 50\ub0C. This study provided the necessary kinetic information that may be useful to define the most suitable condition for industrialized production of \u3b2-cyclodextrin with the high yield and productivity

Encapsulation of Essential Oils by Cyclodextrins: Characterization and Evaluation

The essential oils normally had low physicochemical stability and low solubility in water. These facts limit their industrial applications in general and in food formulations particularly. This chapter characterizes the physicochemical properties and the antioxidant and antimicrobial activities of three encapsulated essential oils – guava leaf, yarrow and black pepper essential oils – in hydroxypropyl-β-cyclodextrin (HPβCD)

Characterization of kefir-like beverages produced from vegetable juices

The aim of this work was to develop new non-dairy fermented beverages using vegetable juices as fermentable substrates. Carrot, fennel, melon, onion, tomato and strawberry juices underwent backslopping fermentations, carried out by water kefir microorganisms. Results indicated that lactic acid bacteria and yeasts were capable of growing in the juices tested. Melon juice registered the highest numbers of microorganisms. Almost all juices underwent a lactic fermentation. After fermentation, there was observance of a decrease of the soluble solid content and an increase of the number of volatile organic compounds. In particular, esters were present in high amounts after the fermentation, especially in strawberry, onion and melon, whereas carrot and fennel registered a significant increase of terpenes. The concentration of alcohols increased, while that of aldehydes decreased. Changes in colour attributes were registered. Strawberry, onion and tomato juices retained a high antioxidant activity after fermentation. The overall quality assessment indicated that carrot kefir-like beverage (KLB) was the product mostly appreciated by the judges. These findings support the further development of vegetable KLBs with additional benefits and functional properties

Nitrogen sources on TPOMW valorization through solid state fermentation performed by Yarrowia lipolytica

This manuscript reports the valorization of two-phase olive mill waste (TPOMW) as raw material and carbon source for solid state fermentation using Yarrowia lipolytica as biocatalyst. Due to its chemical characteristics, a combination of different raw materials (TPOMW and wheat bran, WB) was evaluated and two distinct nitrogen sources were applied as supplementation for lipase production. A TPOMW/WB ratio of 1:1 and supplementation with ammonium sulfate was chosen as the best condition. The productivity in 24 h reached 7.8 U/gh and, after four days of process, only decreased about 35%. Process pH ranged from 5.5-5.9, remaining in an acid range. Thus, the successful use of TPOMW, a watery solid by-product with high content of lipids, as raw material for Yarrowia lipolytica growth and lipase production provided an environmental friendly alternative to valorize such waste.The authors kindly acknowledge the financial aid and research scholarships given by CAPES. Maria Alice Zarur Coelho thanks CNPq (Proc. 308890/ 2013-2)

Synergistic carbon metabolism in a fast growing mixotrophic freshwater microalgal species Micractinium inermum

In recent years microalgae have attracted significant interest as a potential source of sustainable biofuel. Mixotrophic microalgae are able to simultaneously photosynthesise while assimilating and metabolising organic carbon. By combining autotrophic and heterotrophic metabolic pathways biomass productivity can be significantly increased. In this study, acetate-fed mixotrophic Micractinium inermum cultures were found to have a specific growth rate 1.74 times the sum of autotrophic and heterotrophic growth. It was hypothesised that gas exchange between the two metabolic pathways within mixotrophic cultures may have prevented growth limitation and enhanced growth. To determine the extent of synergistic gas exchange and its influence on metabolic activity, dissolved inorganic carbon (DIC), dissolved oxygen (DO) and photosynthesis and respiration rates were measured under different trophic conditions. A 32.7 fold and 2.4 fold increase in DIC and DO concentrations, relative to autotrophic and heterotrophic cultures respectively, were coupled with significant increases in rates of photosynthesis and respiration. These data strongly support the hypothesis of mixotrophic gas exchange within M. inermum cultures. In addition to enhanced growth, this phenomenon may provide reductions in aeration and oxygen stripping costs related to microalgae production

The influence of exogenous organic carbon assimilation and photoperiod on the carbon and lipid metabolism of Chlamydomonas reinhardtii

Microalgae are a promising platform for the production of renewable fuels and oleochemicals. Despite significant research efforts to understand the mechanisms of algal lipid accumulation, the influence of commercially relevant growth conditions on the lipid metabolism is poorly understood. To characterise the impact of differing organic carbon availabilities and photoperiod on the response of the model alga Chlamydomonas reinhardtii to nitrogen stress, the expression of key genes involved in the central carbon metabolism were monitored over a time-course of nitrogen deprivation. In addition, the growth, PSII integrity, chlorophyll content, triacylglycerol (TAG) content, starch content, and fatty acid composition were characterised. Results indicate that both organic carbon availability and photoperiod regulate the lipid accumulation response of C. reinhardtii. Under mixotrophic conditions, organic carbon uptake is favoured over photosynthesis, transcript abundance of lipid synthesis genes rapidly increase and acetate is funnelled to TAG synthesis. In contrast, autotrophic cultures lacking organic carbon experienced a slower rate of photosynthetic degradation and funnelled the majority of sequestered carbon to starch synthesis. Dark periods induced catabolism of both starch and TAG in autotrophic cultures but TAG alone in mixotrophic cultures. Furthermore, diurnal light enhanced starch synthesis under mixotrophic conditions. Finally, transcript analysis indicated that PGD1, important for the routing of oleic acid to TAG, was reliant on organic carbon availability, resulting in reduced C18:1 fatty acid accumulation in autotrophic cultures