Bioethanol production from defatted biomass of Nannochloropsis oculata microalgae grown under mixotrophic conditions.

In order to improve the economic feasibility and environmental sustainability of microalgal bioethanol production, a nontoxic, copious agricultural waste, sugarcane bagasse aqueous extract (SBAE) was used for cultivating Nannochloropsis oculata microalga (NNO-1 UTEX Culture LB 2164) as potential sources of substitutes for traditional nutrition to reduce the costs in cultivation through acid digestion and enzymatic treatment before being fermented by Saccharomyces cerevisiae (NRRLY-2034). The primary target of this research was to find out the ethanol from hydrolysate of the defatted biomass of N. oculata grown mixotrophically on SBAE and CO2 as carbon sources. For acid hydrolysis (AH), the highest carbohydrate yield 252.84 mg/g DW has been obtained with 5.0% (v/v) H2SO4 at 121 °C for 15 min for defatted biomass cultivated mixotrophically on sugarcane bagasse aqueous extract (SBAE) regarding 207.41 mg/g DW for defatted biomass cultivated autotrophically (control treatment). Whereas, the highest levels of reducing sugars has been obtained with 4.0% (v/v) H2SO4 157.47±1.60 mg/g DW for defatted biomass cultivated mixotrophically compared with 135.30 mg/g DW for the defatted control treatment. The combination of acid hydrolysis 2.0% (v/v) H2SO4 followed by enzymatic treatment (AEH) increased the carbohydrate yields to 268.53 mg/g DW for defatted biomass cultivated mixotrophically on SBAE regarding 177.73 mg/g DW for the defatted control treatment. However, the highest levels of reducing sugars have been obtained with 3.0% (v/v) H2SO4 followed by enzyme treatment that gave 232.39±1.77 for defatted biomass cultivated mixotrophically on SBAE and 150.75 mg/g DW for the defatted control treatment. The sugar composition of the polysaccharides showed that glucose was the principal polysaccharide sugar (60.7-62.49%) of N. oculata defatted biomass. Fermentation of the hydrolysates by Saccharomyces cerevisiae for the acid pretreated defatted biomass samples gave ethanol yield of 0.86 g/L (0.062 g/g sugar consumed) for control and 1.17 g/L (0.069 g/g sugar consumed) for SBAE mixotrophic. Whereas, the maximum ethanol yield of 6.17±0.47 g/L (0.26±0.11 g/g sugar consumed) has been obtained with samples from defatted biomass grown mixotrophically (SBAE mixotrophic) pretreated with acid coupled enzyme hydrolysis.

Evaluation of high salinity adaptation for lipid bio-accumulation in the green microalga Chlorella vulgaris.

Aiming at the reutilizing wastewater for algal growth and biomass production, a saline water rejected from reverse osmosis (RO) facility (salinity 67.59 g L-1) was used to cultivate the pre-adapted green microalga Chlorella vulgaris. The inoculum was prepared by growing cells in modified BG-11 medium, and adaptation was performed by applying a gradual increase in salinity (56.0 g L-1 NaCl and 125 ppm FeSO4·7H2O) to the culture in 200 L photobioreactor. Experiments using the adapted alga were performed using original-rejected water (ORW) and treated rejected water (TRW) comparing with the recommended growth medium (BG-11). The initial salinity of ORW was chemically reduced to 39.1 g L-1 to obtain TRW. Vertical photobioreactors (15 L) was used for indoor growth experiments. Growth in BG-11 resulted in 1.23 g L-1, while the next adaptation growth reached 2.14 g L-1 of dry biomass. The dry weights of re-cultivated Chlorella after adaptation were 1.49 and 2.19 g L-1 from ORW and TRW; respectively. The cellular oil content was only 12% when cells grown under control conditions verses to 14.3 and 15.42% with original and treated water, respectively. Induction of stress affected the fatty acid methyl esters (FAMEs) profile and the properties of the resulting biodiesel. The present results indicated that induction of stress by high salinity improves the quality of FAMEs that can be used as a promising biodiesel fuel.

Screening of the bioactive compounds in Amphora coffeaeformis extract and evaluating its protective effects against deltamethrin toxicity in rats.

Pyrethroids are synthetic chemicals similar to the pyrethrins, but more toxic to insects and mammals and persistent in the environment than pyrethrins. This study aimed to identify the bioactive compounds of Amphora coffeaeformis extract (ACE) and to determine their potential protective activity against deltamtherin (DEL) insecticide in rats. Six groups of male albino rats were treated for 4 weeks included the control group, ACE-treated group (772 mg/kg b.w.), DEL-exposed group (13.5 mg/kg b.w.), DEL plus ACE-treated group, and the groups treated with ACE for 14 days before or after DEL. At the end of treatment, blood and tissue samples were collected for biochemical assays. The GC-MS identified 18 compounds; most of them are fatty acid methyl ester, and the HPLC identified 8 polyphenols and significant amounts of vitamins A, C, B1, B2, B9, and E. The in vivo results revealed that DEL induced significant alterations in hematological and serum biochemical parameters, oxidative stress markers, proinflammatory cytokines, and NF-κB. ACE protects against DEL toxicity, and the protection was more pronounced in the groups treated with ACE plus DEL or ACE after DEL suggesting that ACE could be used for the prevention or the treatment of DEL toxicity. It could be concluded that ACE is a promising candidate for the production of bioactive compounds and should be considered in the pharmaceutical and food application.

Combined effect of salinity and pH on lipid content and fatty acid composition of Tisochrysis lutea.

The haptophyte microalga Tisochrysis lutea was heterotrophically grown in F2 medium with different combinations of pH and salinity. Growth, oil content and fatty acids (FAs) profile were determined under each set of conditions. The salinity was adjusted using NaCl at concentrations of 0.4, 0.6, 0.8, or 1.0 M, while pH was adjusted at 7, 8, or 9, and heterotrophic growth was performed using organic carbon in the form of sugar cane industry waste (CM). Fatty acid methyl esters (FAMEs) were identified by gas chromatography. The results showed that pH of 8.0 was the optimal for dry weight and oil production, regardless of the salinity level. At pH 8.0, growth at a salinity of 0.4 M NaCl was optimal for biomass accumulation (1.185 g L-1). Under these conditions, the maximum growth rate was 0.055 g L-1 d-1, with a doubling time of 17.5 h and a degree of multiplication of 2.198. Oil content was maximal (34.87%) when the salinity was 0.4 M and the pH was 9.0. The ratio of saturated to unsaturated FAs was affected by the pH value and salinity, in that unsaturated FAs increased to 58.09% of the total FAs, considerably greater than the value of 40.59% obtained for the control (0.4 M NaCl and pH 8.0).

Outdoor cultivation of the green microalga Chlorella vulgaris under stress conditions as a feedstock for biofuel.

The present work investigated the potential of the green alga Chlorella vulgaris to produce high-quality biofuel under culture stress conditions. The cultivation was carried out in a 1000 l open plate tank system, which provides biomass yields comparable to open pond systems, but with less area needed. Algal biomass and lipid content were measured repeatedly. We compared the two solvent systems n-hexane and hexane/isopropanol (HIP) for extraction efficiency of lipids and applied three different extraction methods Soxhlet, soaking, and soaking followed by Soxhlet (soak-Sox). The combination of the HIP solvent and the soak-Sox provided the highest lipid yield (15.8 ± 0.174). Volumetric biomass and lipid productivity were 0.201 g l-1 day-1 and 31.71 mg l-1 day-1, respectively, whereas areal biomass and lipid productivity were 25.73 g m-2 day-1 and 4.066 g m-2 day-1, respectively. The fatty acid profile by means of gas chromatography resulted in seven fatty acids from C12 to C18. The most abundant fatty acid methyl esters (FAMES) were palmitic (C16:0), oleic (C18:1), and stearic (C18:0) acids. Lipid synthesis enhanced by optimizing the Kuhl growth medium with replacing nitrate by urea (50% N compared to the original recipe) increased salt content (10 g/l NaCl), ferrous sulfate (0.5 g/l), and sodium acetate addition (1 g/l). With regard to density, kinematic viscosity, gravity, pour point, flash point, and cetane number, the Chlorella-biodiesel comply with ASTM and EN standards thus pointing at the high potential of lipids synthesized by Chlorella as a feedstock for biodiesel production.

Bio and phyto-chemical effect of Amphora coffeaeformis extract against hepatic injury induced by paracetamol in rats.

Paracetamol is the most commonly used analgesic-antipyretic drugs. Its excess use causes an acute hepatotoxicity. It is well known that the Bacillariophyta alga Amphora coffeaeformis is rich in many photosynthetic pigments with antioxidant activities as well as a series of biologically active substances. The current work has been designed to study the phytochemical composition of different A. coffeaeformis algal extracts to select the most effective one. It was verified that acetone A. coffeaeformis algal extract is rich in various pigments and polyphenolic compounds (ß-carotene (9.31 ± 0.06 mg·g-1), gallic acid (28.31 µg·g-1), catechin (38.08 µg·g-1) and p-coumaric acid (38.69 µg·g-1)). The pigments and phenolic profiles in acetone extract were determined in addition to isolation of ß-carotene and fucoxanthin which exhibited free radical scavenging activity by 74.80% and 69.40%, respectively. Therefore, the highest total antioxidant capacity and free radical scavenging activity were noticed with this extract. Consequently, efficiency of this algal extract was evaluated against hepatic intoxication induced by paracetamol in rats. The biochemical measurements (liver functions and markers of oxidative stress) were  assayed. Moreover, the native protein, lipid and calcium moieties of native protein patterns in addition to catalase (CAT); peroxidases (POX); α- and ß-esterase (EST) isoenzymes and genomic DNA patterns were electrophoretically detected in liver tissues. It was found that paracetamol caused significant (P < 0.05) elevation in serum liver functions associated with decline in activities of the antioxidant enzymes in that tissues. Also, it caused alterations represented electrophoretically at qualitative level from variations in the bands number and arrangement. So that, the paracetamol treated group was noticed with the lowest similarity index (SI). In addition, it caused abnormalities at the quantitative level through variations in quantity of normal bands. Algal extract restored all the biochemical functions to normal levels in the algal extract simult-treated and pre-treated groups. Furthermore, it exhibited ameliorative effect against the electrophoretic alterations through restoring the absent normal bands and hiding the abnormal ones and hence increasing the SI values especially in the extract simult-treated group. Algal extract exhibited antagonistic effect against the hepatic injury and the deleterious effects induced by paracetamol in the extract simult-treated group.

Remediation of a mixture of analgesics in a stirred-tank photobioreactor using microalgal-bacterial consortium coupled with attempt to valorise the harvested biomass.

An artificial microalgal-bacterial consortium was used to remediate a mixture of analgesics (ketoprofen, paracetamol and aspirin) in a stirred-tank photobioreactor. A hydraulic retention time (HRT) of 3days supported poor treatment because of the formation of p-aminophenol (paracetamol toxic metabolite). Increasing the HRT to 4days enhanced the bioremediation efficiency. After applying an acclimatization regime, 95% removal of the analgesics mixture, p-aminophenol and COD reduction were achieved. However, shortening the HRT again to 3days neither improved the COD reduction nor ketoprofen removal. Applying continuous illumination achieved the best analgesics removal results. The harvested biomass contained 50% protein, which included almost all essential amino acids. The detected fatty acid profile suggested the harvested biomass to be a good biodiesel-producing candidate. The water-extractable fraction possessed the highest phenolic content and antioxidant capacity. These findings suggest the whole process to be an integrated eco-friendly and cost-efficient strategy for remediating pharmaceutical wastewater.