Exogenous GABA supplementation to facilitate Cr (III) tolerance and lipid biosynthesis in Chlorella sorokiniana

Microalgae possess the prospective to be efficiently involved in bioremediation and biodiesel generation. However, conditions of stress often restrict their growth and diminish different metabolic processes. The current study evaluates the potential of GABA to improve the growth of the microalga Chlorella sorokiniana under Cr (III) stress through the exogenous administration of GABA. The research also investigates the concurrent impact of GABA and Cr (III) stress on various metabolic and biochemical pathways of the microalgae. In addition to the control, cultures treated with Cr (III), GABA, and both Cr (III) and GABA treated were assessed for accurately analysing the influence of GABA. The outcomes illustrated that GABA significantly promoted growth of the microalgae, resulting in higher biomass productivity (19.14 mg/L/day), lipid productivity (3.445 mg/L/day) and lipid content (18%) when compared with the cultures under Cr (III) treatment only. GABA also enhanced Chl a content (5.992 μg/ml) and percentage of protein (23.75%). FAMEs analysis by GC-MS and total lipid profile revealed that GABA treatment can boost the production of SFA and lower the level of PUFA, a distribution ideal for improving biodiesel quality. ICP-MS analysis revealed that GABA supplementation could extend Cr (III) mitigation level up to 97.7%, suggesting a potential strategy for bioremediation. This novel study demonstrates the merits of incorporating GABA in C. sorokiniana cultures under Cr (III) stress, in terms of its potential in bioremediation and biodiesel production without disrupting the pathways of photosynthesis and protein production.

A phyco-nanobionics biohybrid system for increased carotenoid accumulation in C. sorokiniana UUIND6

Recent advancements in "phyco-nanobionics" have sparked considerable interest in the ability of microalgae to synthesize high-value natural bioactive compounds such as carotenoid pigments, which have been highlighted as an emergent and vital bioactive compound from both industrial and scientific perspectives. Such bioactive compounds are often synthesized by either altering the biogenetic processes existing in living microorganisms or using synthetic techniques derived from petroleum-based chemical sources. A bio-hybrid light-driven cell factory system was established herein by using harmful macroalgal bloom extract (HMBE) and efficient light-harvesting silver nanoparticles (AgNPs) to synthesize HMBE-AgNPs and integrating the synthesized HMBE-AgNPs in various concentrations (1, 2.5, 5 and 10 ppm) into the microalgae C. sorokiniana UUIND6 to improve the overall solar-to-chemical conversion efficiency in carotenoid pigment synthesis in microalgae. The current study findings found high biocompatibility of 5 ppm HMBE-AgNP concentration that can serve as a built-in photo-sensitizer and significantly improve ROS levels in microalgae (6.75 ± 0.25 μmol H2O2 g-1), thus elevating total photosynthesis resulting in a two-fold increase in carotenoids (457.5 ± 2.5 μg mL-1) over the native microalgae without compromising biomass yield. NMR spectroscopy was additionally applied to acquire a better understanding of pure carotenoids derived from microalgae, which indicated similar peaks in both spectra when compared to β-carotene. Thus, this well-planned bio-hybrid system offers a potential option for the cost-effective and long-term supply of these natural carotenoid bio-products.

Evaluation of the mechanisms underlying altered fatty acid biosynthesis in heterotrophic microalgal strain Chlorella sorokiniana during biodegradation of phenol and p-nitrophenol

Phenolic compounds have become a severe environmental concern due to water contamination, affecting the sustainability of the ecosystem. The microalgae enzymes have enticed for the efficient involvement in the biodegradation of phenolics compound in metabolic processes. In this investigation, the oleaginous microalgae Chlorella sorokiniana was cultured heterotrophically under the influence of phenol and p-nitrophenol. The enzymatic assays of algal cell extracts were used to decipher the underlying mechanisms for phenol and p-nitrophenol biodegradation. A reduction of 99.58% and 97.21% in phenol and p-nitrophenol values, respectively, was recorded after the 10th day of microalgae cultivation. Also, the biochemical components in phenol, p-nitrophenol, and control were found to be 39.6 ± 2.3%, 36.7 ± 1.3%, and 30.9 ± 1.8% (total lipids); 27.4 ± 1.4%, 28.3 ± 1.8%, and 19.7 ± 1.5% (total carbohydrates); and 26.7 ± 1.9%, 28.3 ± 1.9%, and 39.9 ± 1.2% (total proteins), respectively. The GC-MS and 1H-NMR spectroscopy attested the incidence of fatty acid methyl esters in the synthesized microalgal biodiesel. The activity of catechol 2,3-dioxygenase and hydroquinone 1,2-dioxygenase in microalgae under heterotrophic conditions has conferred the ortho- and hydroquinone pathways for phenol and p-nitrophenol biodegradation, respectively. Also, the acceleration of fatty acid profiles in microalgae is deliberated under the impact of the phenol and p-nitrophenol biodegradation process. Thus, microalgae enzymes in the metabolic degradation process of phenolic compounds encourage ecosystem sustainability and biodiesel prospects due to the increased lipid profiles of microalgae.

Impact of aquatic microplastics and nanoplastics pollution on ecological systems and sustainable remediation strategies of biodegradation and photodegradation

The extreme degree of microplastics contamination and its negative impact on ecosystems has become a serious and emerging global concern. Microplastics are mainly generated from products that are used primarily in our everyday lives and are also generated from the fragmentation of larger plastic wastes. It easily penetrates the food chain and, when ingested by aquatic animals or humans, can pose serious health problems. Recently, several technologies have been developed to control the unrestricted spread of microplastics and possibly eradicate them; however, still under investigation. In this review, we have illustrated the types of microplastics, their harmful effect on living things, and the progress to degrade them to protect the environment and life on earth. Several promising and eco-friendly technologies including microbial and enzymatic approaches are enticing to eliminate the microplastics. Also, the photodegradation of microplastics contaminations appeals as a more fascinating approach. The metal oxide-assisted photodegradation of microplastics has also been taken into account. This work presented an impact on the comprehensive research for the effective degradation of different microplastic compositions as well as emerging green approaches for a sustainable environment and a healthier life.

Impact of pyrene (polycyclic aromatic hydrocarbons) pollutant on metabolites and lipid induction in microalgae Chlorella sorokiniana (UUIND6) to produce renewable biodiesel

Pyrene (polycyclic aromatic hydrocarbon), an anthropogenic organic pollutant prevalent in various ecological units, receives more attention for bioremediation and energy transformation using microalgae. In this study, we have used pyrene pollutant (50-500 ppm) to evaluate the half-maximal inhibitory concentrations (IC₅₀) of Chlorella sorokiniana and the impact on metabolites as well as the induction of lipid biosynthesis to produce renewable biodiesel. Pyrene concentration at 230 ppm (IC₅₀) caused half-maximum inhibition for the 96 h incubation. The harvest in the stationary stage (day 16) for C. sorokiniana revealed a biomass generation of 449 ± 7 mg L^-1 and 444 ± 8 mg L^-1 dcw in the control medium and pyrene IC₅₀ medium, respectively. An insignificant decline in biomass generation (1.2%) was observed due to the stress effect of the pyrene IC₅₀ medium on metabolic biosynthesis. Although contrary to biomass generation, IC₅₀ of pyrene assisted to induce lipid biosynthesis in C. sorokiniana. The improvement in lipid biosynthesis was observed as ~24% higher in pyrene IC₅₀ compared to the control medium. The chemical composition of the microalgae biomass, metabolites, and lipids was examined using FTIR spectra. The extracted lipid was transesterified to produce biodiesel via methanolic-H₂SO₄ catalysis. The renewable biodiesel obtained was evaluated using FTIR and ¹H NMR spectra. The transformation efficiency of the lipid of C. sorokiniana in biodiesel was calculated as ~81%. This research offers the incentive in lipid biosynthesis in microalgae cells using pyrene for the production of renewable and sustainable ecological biofuels along with bioremediation of pyrene.

Graphitic bio-char and bio-oil synthesis via hydrothermal carbonization-co-liquefaction of microalgae biomass (oiled/de-oiled) and multiple heavy metals remediations

Thermochemical transformation of microalgae biomass into graphitic bio-chars entices as proficient bio-adsorbents for heavy metal contaminants. This study explores the synergistic impact of Chlorella sorokiniana on biomass generation and wastewater remediation in high rate algae pond (HRAP). Biomass produced was applied for hydrothermal carbonization-co-liquefaction (HTCL). The structural and morphological characteristics of HTCL products (i.e. bio-chars and bio-oils) have been systematically studied by XRD, Raman, FTIR, elemental analyzer, SEM, BET, and ¹H NMR spectroscopy. The crystallite size of the graphite 2H indexing planes was to be 4.65 nm and 14.07 nm in the bio-chars of oiled biomass (MB-OB) and de-oiled biomass (MB-DOB), respectively. The increase in the I_D/I_G ratio of MB-DOB indicated the highly disordered graphitic structure due to the appearance of carbonyl, hydroxyl, and epoxy functionalities in the line of high C/N and low C/H ratio. Also, the multiple heavy metals remediation of MB-DOB revealed better efficiency as ~100% in 720 min. The kinetics analysis shows the correlation coefficient of pseudo-second-order is well fitted compared to the pseudo-first-order. The Langmuir adsorption model signifies the adsorption of heavy metal ions in a monolayer adsorption manner. The study proposes the microalgae bio-char potential for multiple heavy metals remediation alongside bio-oils.

Ethno-pharmacological insulin signaling induction of aqueous extract of Syzygium paniculatum fruits in a high-fat diet induced hepatic insulin resistance

ETHNOPHARMACOLOGICAL RELEVANCE

The ethnopharmacological significance of the fruits of Syzygium paniculatum Gaertn (Magenta Cherry) is widely recognized in the Indian traditional medicine system to treat various disorders, such as diabetes, hyperlipidaemia, hypertension, and cardiovascular problems.

AIM OF THE STUDY

This research work investigated the supplementation of the aqueous extract of S. paniculatum fruit (AESPF) on liver function; the molecular effects on the expression of the protein of insulin receptor (IR) and insulin receptor substrate 1 (IRS-1) in high-fat diet-induced hepatic insulin resistance in the rat model.

MATERIALS AND METHODS

High-fat diet was used to induce obesity in albino Wistar for 120 days. Biochemical, enzymatic, and histopathological analysis, as well as analysis of hepatic insulin resistance proteins and expression of IRS-1, were performed.

RESULTS

The supplementation of AESPF with a dose of 100 mg/kg bw significantly reduced bodyweight, blood sugar, insulin, lipid profiles, and liver enzymes. Hepatic insulin resistance was improved with a reduced level of IR and IRS-1 to protein levels. HFD alters the sensitivity of hepatocytes to insulin due to the down-regulation of insulin receptor proteins.

CONCLUSIONS

The fruits of S. paniculatum possess biological activities to alleviate all risky effects by regulating hepatic lipogenesis activity that can be used in the progress of medication for HFD-induced hepatic insulin resistance and metabolic disorders.

Pathophysiology of high fat diet induced obesity: impact of probiotic banana juice on obesity associated complications and hepatosteatosis

The high fat diet alters intestinal microbiota due to increased intestinal permeability and susceptibility to microbial antigens leads to metabolic endotoxemia. But probiotic juices reported for various health benefits. In this background we hypothesized that pectinase treated probiotic banana juice has diverse effects on HFD induced obesity and non-alcoholic steatohepatitis. 20 weeks fed HFD successfully induced obesity and its associated complications in experimental rats. The supplementation of probiotic banana juice for 5 months at a dose of 5 mL/kg bw/day resulted significant decrease (p < 0.05) in body weight (380 ± 0.34), total fat (72 ± 0.8), fat percentage (17 ± 0.07) and fat free mass (165 ± 0.02). Reduction (p < 0.05) in insulin resistance (5.20 ± 0.03), lipid profile (TC 120 ± 0.05; TG 160 ± 0.24; HDL 38 ± 0.03), liver lipid peroxidation (0.7 ± 0.01), hepatic enzyme markers (AST 82 ± 0.06; ALT 78 ± 0.34; ALP 42 ± 0.22), and hepatic steatosis by increasing liver antioxidant potential (CAT 1.4 ± 0.30; GSH 1.04 ± 0.04; SOD 0.82 ± 0.22) with normal hepatic triglycerides (15 ± 0.02) and glycogen (0.022 ± 0.15) contents and also showed normal liver size, less accumulation of lipid droplets with only a few congestion. It is concluded that the increased intestinal S. cerevisiae yeast can switch anti-obesity, antidiabetic, antioxidative stress, antioxidant and anti-hepatosteatosis effect. This study results will have significant implications for treatment of NAFLD.

Small-scale phyco-mitigation of raw urban wastewater integrated with biodiesel production and its utilization for aquaculture

A low-cost small-scale high-rate algal pond (HRAP) was constructed to investigate the synergistic potential of a novel oleaginous microalga, Chlorella sorokiniana for phyco-mitigation, and biodiesel production using raw urban wastewater. An enhanced nutrient removal (97%), total organic carbon (74%), alkalinity (70%) and hardness (75%) from the wastewater was obtained. The microalga dominated in the HRAP as ~90% increase in the dissolved oxygen with high biomass (1.13 g/L) was noted. The microalga biomass showed sufficient lipid content (~31% of dry cell weight) as compared to control (Bold's Basal media). The total lipid profiling of the microalga cultivated in wastewater showed augmentation in the levels of both storage and neutral lipids with good quality fatty acids composition. Moreover, the sucker fishes grew healthy in the treated wastewater with an increase in body weight.