Macroalgae Bioplastics: A Sustainable Shift to Mitigate the Ecological Impact of Petroleum-Based Plastics

The surge in global utilization of petroleum-based plastics, which notably heightened during the COVID-19 pandemic, has substantially increased its harm to ecosystems. Considering the escalating environmental impact, a pivotal shift towards bioplastics usage is imperative. Exploring and implementing bioplastics as a viable alternative could mitigate the ecological burden posed by traditional plastics. Macroalgae is a potential feedstock for the production of bioplastics due to its abundance, fast growth, and high cellulose and sugar content. Researchers have recently explored various methods for extracting and converting macroalgae into bioplastic. Some of the key challenges in the production of macroalgae bioplastics are the high costs of large-scale production and the need to optimize the extraction and conversion processes to obtain high-quality bioplastics. However, the potential benefits of using macroalgae for bioplastic production include reducing plastic waste and greenhouse gas emissions, using healthier materials in various life practices, and developing a promising area for future research and development. Also, bioplastic provides job opportunities in free enterprise and contributes to various applications such as packaging, medical devices, electronics, textiles, and cosmetics. The presented review aims to discuss the problem of petroleum-based plastic, bioplastic extraction from macroalgae, bioplastic properties, biodegradability, its various applications, and its production challenges.

Cyanobacteria as a Valuable Natural Resource for Improved Agriculture, Environment, and Plant Protection

Taking into consideration, the challenges faced by the environment and agro-ecosystem make increased for suggestions more reliable methods to help increase food security and deal with difficult environmental problems. Environmental factors play a critical role in the growth, development, and productivity of crop plants. Unfavorable changes in these factors, such as abiotic stresses, can result in plant growth deficiencies, yield reductions, long-lasting damage, and even death of the plants. In reflection of this, cyanobacteria are now considered important microorganisms that can improve the fertility of soils and the productivity of crop plants due to their different features like photosynthesis, great biomass yield, ability to fix the atmospheric N2, capability to grow on non-arable lands, and varied water sources. Furthermore, numerous cyanobacteria consist of biologically active substances like pigments, amino acids, polysaccharides, phytohormones, and vitamins that support plant growth enhancement. Many studies have exposed the probable role of these compounds in the alleviation of abiotic stress in crop plants and have concluded with evidence of physiological, biochemical, and molecular mechanisms that confirm that cyanobacteria can decrease the stress and induce plant growth. This review discussed the promising effects of cyanobacteria and their possible mode of action to control the growth and development of crop plants as an effective method to overcome different stresses.

Graphical Abstract

Morpho-anatomical, and chemical characterization of some calcareous Mediterranean red algae species

Climatic changes are anticipated to have a detrimental effect on calcifying marine species. Calcareous red algae may be especially vulnerable to seasonal variations since they are common and essential biologically, but there is little research on the morpho-anatomical, and chemical characterization of such species. This study conducted the seasonal investigation of the three dominant Mediterranean calcified red algae. Morphological and 18S rRNA analysis confirmed the identification of collected species as Corallina officinalis, Jania rubens, and Amphiroa rigida. In general, C. officinalis was represented in the four seasons and flourishing maximum in autumn (70% of total species individuals). While J. rubens species was represented in winter, autumn, and spring and completely absent in summer. A. rigida was abundant only in the summer season by 40%. A full morphological and anatomical description of these species were examined, and their chemical compositions (carbohydrate, protein, lipid, pigments, and elements content) were assessed in different seasons, where carbohydrates were the dominant accumulates followed by proteins and lipids. Pearson correlation analysis confirmed a positive correlation between salinity level and nitrogenous nutrients of the seawater with the pigment contents (phycobiliproteins, carotenoids, and chlorophyll a) of the studied seaweeds. The results proved that calcified red algae were able to deposit a mixture of calcium carbonates such as calcite, vaterite, calcium oxalate, calcite-III I calcium carbonate, and aragonite in variable forms depending on the species.

Role of Antioxidant Enzymes and Glutathione S-Transferase in Bromoxynil Herbicide Stress Tolerance in Wheat Plants

BACKGROUND

Numerous pesticides and herbicides used in excess cause oxidative stress in plants. These chemicals protect plants from weeds and pests, but they also have very negative side effects, making them common abiotic stressors. One of the most significant nutritional crops in the world is the wheat plant. Conditions of herbicide stress have a negative impact on the plant's phonological phases and metabolic pathways. Plants primarily make an effort to adjust to the environment and develop oxidative homeostasis, which supports stress tolerance.

METHODS

When controlling broadleaf weeds that emerge after cereal crop plants have been planted, bromoxynil is frequently used as a selective-contact herbicide. This study looked at the effects of the cyanobacteria Arthrospira platensis and Nostoc muscorum aqueous extracts, tryptophan, and bromoxynil (Bh) alone or in combination on wheat plant growth parameters. Both tryptophan and cyanobacterial extract were used as chemical and natural safeners against Bh application. The antioxidant activity and transcriptome studies using qRT-PCR were assayed after 24, 48, 72, 96 h, and 15 days from Bh application in the vegetation stage of wheat plants (55 days old).

RESULTS

In comparison with plants treated with Bh, wheat plants treated with cyanobacteria and tryptophan showed improvements in all growth parameters. Following application of Bh, wheat plants showed reduced glutathione content, as well as reduced antioxidant enzyme activities of superoxide dismutase, catalase, glutathione peroxidase, and glutathione-s-transferase. The combination of different treatments and Bh caused alleviation of the harmful effect induced by Bh on the measured parameters. Additionally, the expression of glutathione synthase and glutathione peroxidase, in addition to those of three genes (Zeta, Tau, and Lambda) of the GST gene family, was significantly upregulated when using Bh alone or in combination with different treatments, particularly after 24 h of treatment.

CONCLUSION

The current study suggests using cyanobacterial extracts, particularly the A. platensis extract, for the development of an antioxidant defense system against herbicide toxicity, which would improve the metabolic response of developed wheat plants.

The role of silver nanoparticles biosynthesized by Anabaena variabilis and Spirulina platensis cyanobacteria for malachite green removal from wastewater

In this study, biosynthesis of silver nanoparticles (AgNPs) using two species of cyanobacteria, Anabaena variabilis (Kütz) and Spirulina platensis (Gomont) was investigated and evaluated for dye removing capacity. The formation of AgNPs was detected by the change in colour using UV-Vis spectroscopy and further characterised by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). The obtained AgNPs were spherical to oval with average particle size of 17.9 and 26.4 nm for S. platensis and A. variabilis, respectively. These AgNPs were applied as bio-sorbent for the removal of malachite green (MG) dye released into wastewater. Within the tested initial concentration range of MG, the reaction exhibited first order kinetics model as monitored via UV spectroscopy. As the dye concentration decreased, the removal efficiency increased to reach 93% for S. platensis and 82% for A. variabilis AgNPs. The results also indicated that increased AgNPs concentration enhanced the MG removal with an efficiency up to 88% and 81% for S. platensis and A. variabilis AgNPs, respectively. The smaller particle diameter and larger specific surface area of S. platensis AgNPs enabled boosted catalytic activity for dye removal than those of A. variabilis. After the treatment with AgNPs, the resultant dye- AgNPs-free effluent proved non-toxic to Triticum aestivum L (Giza 171) seedlings, implying their safety for cultivation practices.

Thermal analysis and enhanced visual technique for assessment of microplastics in fish from an Urban Harbor, Mediterranean Coast of Egypt

Enhanced visual counting technique coupled with combustion analysis and differential scanning calorimetry (DSC) was applied to assess microplastics (MPs) contamination in fish digestive tracts from Eastern Harbor, Egypt, to provide a simple and economic method for MPs assessment. This was the first study in Egypt to quantify MPs in fish. Plastic particles were detected in all fish samples, represented by seven thermoplastic polymers. The average number of MPs was at its highest level in Siganus rivulatus, Diplodus sargus, and Sardinella aurita (7527, 3593, and 1450MPs fish^-1, resp.) and the lowest in Sphyraena viridensis and Atherina boyeri (46 and 28MPs fish^-1, respectively). The average weight of MPs as measured by combustion ranged from 302mg kg^-1 in S. rivulatus to 2mg kg^-1 in Terapon puta.

Natural products from some soil cyanobacterial extracts with potent antimicrobial, antioxidant and cytotoxic activities

The ethyl acetate, n hexane and methanol extracts of six cyanobacterial species isolated from paddy fields in Egypt were assessed for their antimicrobial activity, using disc diffusion method. Oscillatoria acuminata, Oscillatoria amphigranulata and Spirulina platensis methanolic extracts showed the highest inhibition zones. Minimum inhibitory concentration of O. amphigranulata extract recorded lower values using agar streak dilution method. O. acuminata methanolic extract exhibited the highest antioxidant activity (6.58 and 34.60 % using DPPH (2, 2- diphenyl-1- picrylhydrazyl) and ABTS+ (2, 2-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) methods, respectively, followed by O. amphigranulata then S. platensis. Similarly, O. acuminata methanolic extract showed very strong cytotoxicity activity against HepG2 and HCT-116 cell lines and strong activity with MCF-7 cell lines. O. amphigranulata extract showed strong cytotoxicity for HepG2 and HCT-116 as well as moderate cytotoxicity for MCF-7 cell line. Whereas, S. platensis extract exhibited moderate cytotoxicity for all cell lines. Results of gas chromatography/mass spectroscopy analysis pointed out that the potential activity of these cyanobacterial extracts might be attributed to a synergistic effect between their pronounced contents of fatty acids, alkaloids, phytol, hydrocarbons, phenolics and phthalates, especially fatty acids. We recommend cyanobacteria as a rich source of natural products with potent pharmacological and medical applications.

Antimicrobial, Antioxidant, and Anti-Tumor Activities of Sargassum linearifolium and Cystoseira crinita from Egyptian Mediterranean Coast

Brown algae earned importance by virtue of their promising secondary metabolites of reasonable biological activities. Herein, the antioxidant, antimicrobial, and anticancer effects of crude extracts obtained from two Egyptian brown seaweeds, Sargassum linearifolium and Cystoseira crinita were evaluated. Phytochemical and GC-MS analyses revealed numerous active secondary metabolites in C. crinita cold methanolic extract (CCME) and S. linearifolium hot aqueous extract (SHAE). Both SHAE and CCME exhibited comparable DPPH (124.5 vs 125.6 µg/ml) and ABTS (257.1 vs 254.8 µg/ml) scavenging activities, respectively. Moreover, both crude extracts exhibited antimicrobial activity against various pathogenic microorganisms. Interestingly, employing MTT assay revealed cytotoxic effects of both extracts against a panel of cancer cells, where CCME showed a strong cytotoxic activity against MCF-7 cells (IC50 = 18.0 ± 0.74 µg/ml), while SHAE exhibited a moderate effect (IC50 = 31.1 ± 1.04 µg/ml). Increased mRNA and protein expression of Bax and Beclin-1 as well as the decreased expression of Bcl-2 revealed the ability of both extracts to induce apoptosis and autophagy in MCF-7 cells. Collectively, these findings provide evidence for antioxidant, antimicrobial, as well as anticancer effects driven by the two brown seaweeds that may underlay their plausible application in the therapeutic uses.

Variation in oxidative stress indices of two green seaweeds growing under different heavy metal stresses

Concentrations of nine heavy metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) were determined in the green seaweed species Cladophora glomerata and Ulva compressa collected from El-Mex and Sidi Kirayr locations. The heavy metal concentrations in algal tissues were in direct correlation with their soluble concentrations in seawater with the descending order: Fe<Mn<Zn<Cu<Cr<Pb<Ni<Cd<Co. The bioaccumulation factor of iron and copper was higher in both tested species collected from El-Mex, while it was maximum for cadmium in Sidi Kirayr location. This metal contamination led to apparent alternation in algal thalli morphology. The results showed that C. glomerata had a superior adaptation to metal stress than U. compressa, due to its ability to produce non-enzymatic and enzymatic compounds for scavenging of the produced reactive oxygen species. The recorded contents of the oxidative stress indices (phenols, antioxidant activity, lipid peroxidation, hydrogen peroxide, and ascorbic acid) and the antioxidant enzymes (catalase, peroxidase, and superoxide dismutase) were higher in both tested seaweeds from El-Mex bay. Additionally, the estimated metal pollution index and pollution load index for the tested algae and seawaters ensured their ability as metal pollution bioindicators for monitoring marine environment quality and as biomarkers for oxidative damage assessment.

Acute splenic sequestration crisis in children with sickle cell disease

OBJECTIVE

The aim of this study was to demonstrate the clinical experience with acute splenic sequestration crisis in children with sickle cell disease, followed in Madina Maternity & Children's Hospital, Madina Al-Munawara, Kingdom of Saudi Arabia.

METHODS

A retrospective review of hospital case notes of all children with acute splenic sequestration in sickle cell disease, was carried out in the Pediatric Hematology unit at Madina Maternity & Children's Hospital between 1993 through to 2000.

RESULTS

One hundred and twenty children with sickle cell disease were registered and followed in Madina Maternity & Children's Hospital. Out of these, 8 had acute splenic sequestration crisis with a prevalence of 7%. Seven were Saudi and one was non-Saudi (Sudanese), 7 had sickle cell anemia and one had Sickle b-Thalassemia. The female to male ratio was 3:1, 2 patients presented with associated painful crisis. In 50% of the patients, the spleen was not palpable before the attack of acute splenic sequestration crisis. All patients had major splenic sequestration with circulatory collapse, 4 patients (50%) had recurrence and 3 (37.5%) had splenectomy carried out at the age of 2 years. The steady state hematological data did not show any risk factor for acute splenic sequestration crisis and none of our patients died.

CONCLUSION

We conclude that acute splenic sequestration crisis is of relatively high prevalence in the western region of the Kingdom of Saudi Arabia, and is of severe type. Management measures recommended are, prevention of sickle cell disease through health education, reduction of consanguineous marriage, implementation of premarital and neonatal screening programs for hereditary blood disease, regular follow-up and education of parents to palpate the spleen in an established sickle cell case.

Splenectomy in thalassaemia major: experience at Madina Maternity and Children's Hospital, Saudi Arabia

Eighteen (32%) of 56 children with thalassaemia major, whose ages ranged from 5 to 12 years (mean 8.8), underwent splenectomy at Madina Maternity and Children's Hospital, Saudi Arabia during the period January 1992 to December 1999. This retrospective study was undertaken with the aim of discovering the outcome. The indications for splenectomy were increased transfusion requirements and massive splenomegaly in 17 children and splenic abscess in one. Polyvalent pneumococcal and Haemophilus influenza vaccines were not available and all the children therefore received intramuscular benzathine penicillin prophylaxis prior to surgery and oral penicillin prophylactically afterwards. Post-splenectomy septicaemia did not occur. The mean transfusion requirement reduced from 2 to 4 weeks and the mean pre-transfusion haemoglobin rose from 6 to 9 g/dl. There were no deaths. We conclude that splenectomy can be performed safely in children over 5 years of age with thalassaemia, and that pre- and post-operative penicillin can be given prophylactically in the absence of the recommended vaccines.