The increasing demand for microalgae biomass, driven by its applications in biofuel, food, and pharmaceuticals, necessitates the development of cost-effective cultivation methods. Utilizing food waste as an alternative nutrient source for microalgae cultivation offers a promising solution to reduce operational expenses. In this review, we analyze the nutrient profiles of processed vegetable and fruit waste, palm kernel residue, and spent coffee grounds and address their compatibility with the nutritional needs for microalgae growth. For instance, it was estimated that approximately 4.937 kg and 6.302 kg of banana peel extract powder are needed to provide the equivalent nitrogen concentration for microalgae cultivation as used in Zarrouk’s and BG-11 medium, respectively. However, the final nutrient availability for microalgae cultivation depends on the pretreatment methods. The pretreatment processes required to convert food waste into cultivation media, such as composting and anaerobic digestion, are discussed. Besides, the direct use of food waste as a supporting matrix where microalgae cells can attach and grow is addressed. The review further examines the economic feasibility of using these food wastes as nutrient sources by presenting a detailed cost analysis covering both capital and operational expenditures. The key challenges, including nutrient variability and contamination risks, are evaluated, highlighting the need for standardized processing techniques. The review also underscores the importance of further research to optimize these processes and establish the feasibility of large-scale implementation, promoting a sustainable and economically viable future for microalgae cultivation.

Heavy metal contamination of water sources has long been a silent yet potent threat, endangering environmental and human health. Conventional wastewater treatments are costly due to high infrastructure expenses, energy consumption, and chemical usage. These treatments lead to secondary environmental pollution, such as producing toxic sludge, greenhouse gaseous emissions, and residual pollutants discharges. Therefore, more sustainable and cost-effective wastewater treatment alternatives are needed to overcome these challenges. Microalgae biosorption and bioaccumulation can bioremediate wastewater by effectively removing heavy metals and other contaminants, such as nitrate and phosphate. By utilizing sunlight and CO2 for growth, microalgae cultivation reduces the need for expensive chemicals and energy-intensive operations in wastewater treatment. Additionally, microalgae can potentially convert heavy metal ions from wastewater into metal nanoparticles, providing a dual benefit of bioremediation and resource recovery. The primary objectives of this review are to assess the effectiveness of microalgae in heavy metal bioremediation and nanoparticle synthesis while also identifying critical research gaps and future directions for optimizing this biotechnology. Heavy metal ions in wastewater can be used as a metal precursor, and metal nanoparticles can be synthesized from wastewater. A review methodology was carried out to assess the availability of literature for readers to identify the research trends and gaps. Mechanisms of microalgae for the biogenesis of metal nanoparticles, including activation, growth, and termination phases, were elucidated. Various chemical interactions between metal ions and functional groups of microalgae, including amine (-NH2), carboxyl (-COOH), phosphate (-PO4), and hydroxyl (-OH) groups were evaluated. Nonetheless, this review also identifies the current challenges and future research directions for optimizing microalgae biotechnology in heavy metal bioremediation and nanoparticle biogenesis.

The insect larvae Protaetia brevitarsis seulensis have recently been researched as a nutritious food source and concentrated on their environmental impacts. Therefore, their gut microbiota has been studied to elucidate their effects and roles on the environment. Of the abundance of bacterial genus identified based on the 16S rRNA genes from isolates of the gut of insect larva Protaetia brevitarsis seulensis, six of the prominent genus were identified as Bacillus (40.2%), Cellulosimicrobium (33.5%), Microbacterium (2.8%), Streptomyces (3%), Krasilnikoviella (17.5%), and Isoptericola (3%) and their similarity of 16S rRNA blast changed from 99 to 100%. Cellulosimicrobium protaetiae BI34T showed strong denitrification and cellulose degradation activity. The newly complete genome sequence of BI34T and the genomes of five species was published in the genus Cellulosimicrobium with emphasis on the denitrification and secondary metabolite genes. In order to elucidate the relationship between the strain BI34T and the host insect larva, the whole-genome sequence was analyzed and compared with the genomes of five strains in the same genus, Cellulosimicrobium, loaded from GenBank. Our results revealed the composition of the gut microbiota of the insect larvae and analyzed the genomic data for the new strain to predict its characteristics and to understand the nitrogen metabolism pathway.

Live microorganisms known as probiotics, which have various beneficial claims, have undergone substantial research and commercial exploration in a wide range of goods across the world. Many scientific studies have demonstrated their advantages for both human and animal health. The two primary probiotic bacterial species are Lactobacillus sp. and Bifidobacterium sp. The multi-billion health food industry has employed probiotics with a variety of dietary matrices, which are briefly reported. The history of probiotics, their use in food and medicine, and the latest developments in probiotic processes such as microencapsulation and genetically engineered probiotics are all covered in this review.

In the effort of isolating novel microbial species, the strain PL0132 T was isolated from a fallen leaf under fresh water at a stream, which glided when grown on a tap water medium (without nutrients). The strain was determined to be Gram-negative, strictly aerobic, and rod-shaped, which grew optimally at 25 °C, pH 6–7, and the strain tolerates 1% (w/v) NaCl concentration. The complete genome of strain PL0132 T comprises one contig with a sequencing depth of 76×, consisting of 8,853,064 base pairs and the genomic DNA G + C content was 46.7% (genome). 16S rRNA gene sequence analysis revealed that strain PL0132 T represents a member of the phylum Bacteroidetes and is affiliated with the genus Spirosoma . Based on genomic, phenotypic, and chemotaxonomic characteristics, the strain PL0132 T represents a novel species of the genus Spirosoma , for which the name Spirosoma foliorum sp. nov. is proposed (= KCTC 72228 T = InaCC B1447 T ).

The demand for astaxanthin has been increasing for many health applications ranging from pharmaceuticals, food, cosmetics, and aquaculture due to its bioactive properties. Haematococcus pluvialis is widely recognized as the microalgae species with the highest natural accumulation of astaxanthin, which has made it a valuable source for industrial production. Astaxanthin produced by other sources such as chemical synthesis or fermentation are often produced in the cis configuration, which has been shown to have lower bioactivity. Additionally, some sources of astaxanthin, such as shrimp, may denature or degrade when exposed to high temperatures, which can result in a loss of bioactivity. Producing natural astaxanthin through the cultivation of H. pluvialis is presently a demanding and time-consuming task, which incurs high expenses and restricts the cost-effective industrial production of this valuable substance. The production of astaxanthin occurs through two distinct pathways, namely the cytosolic mevalonate pathway and the chloroplast methylerythritol phosphate (MEP) pathway. The latest advancements in enhancing product quality and extracting techniques at a reasonable cost are emphasized in this review. The comparative of specific extraction processes of H. pluvialis biological astaxanthin production that may be applied to large-scale industries were assessed. The article covers a contemporary approach to optimizing microalgae culture for increased astaxanthin content, as well as obtaining preliminary data on the sustainability of astaxanthin production and astaxanthin marketing information.

Multidrug resistance to pathogens has posed a severe threat to public health. The threat could be addressed by antimicrobial peptides (AMPs) with broad-spectrum suppression. In this study, Brevibacillus halotolerans 7WMA2, isolated from marine sediment, produced AMPs against Gram-positive and Gram-negative bacteria. The AMPs were precipitated by ammonium sulfate 30

The supernatant from Bacillus subtilis possessed significant antifungal activity against Fusarium oxysporum and Rhizoctonia solani, two harmful pathogenic fungi. In this study, antifungal compounds were purified from the extracellular extract of B. subtilis including volatile organic compounds (VOCs) and membranes protein. The antifungal compound was purified from B. subtilis by using a silica gel column with a solvent system of chlo-roform: ethyl acetate (7:3, v/v). Based on spectral data, the chemical structure was identified as (3R,4R)-and (3S,4S)-3.4-dihydroxyl-3-methyl-2-pentanone (acetylbutanediol)-volatile organic compounds. The 3.4-dihy-droxyl-3-methyl-2-pentanone showed high antifungal activity against Fusarium oxysporum and Rhizoctonia sol-ani. Additionally, we isolated a novel antifungal protein with a molecular mass of 40 kDa. The results of Matrix -assisted laser desorption/ionization-Time of flight (MALDI-TOF) mass suggested that the functional molecule was outer membrane proteins (OMPs). The purified secondary metabolites retained antifungal activity against R. solani after being treated at 100 degrees C for 30 min. Treatment with the crude broth produced from Bacillus subtilis highly inhibited the growth of tested pathogens. Hence, it exhibited the potential of the antifungal compounds from B. subtilis for use as a biocontrol agent against fungi.

Surfactants have always been a prominent chemical that is useful in various sectors (e.g., cleaning agent production industry, textile industry and painting industry). This is due to the special ability of surfactants to reduce surface tension between two fluid surfaces (e.g., water and oil). However, the current society has long omitted the harmful effects of petroleum-based surfactants (e.g., health issues towards humans and reducing cleaning ability of water bodies) due to their usefulness in reducing surface tension. These harmful effects will significantly damage the environment and negatively affect human health. As such, there is an urgency to secure environmentally friendly alternatives such as glycolipids to reduce the effects of these synthetic surfactants. Glycolipids is a biomolecule that shares similar properties with surfactants that are naturally synthesized in the cell of living organisms, glycolipids are amphiphilic in nature and can form micelles when glycolipid molecules clump together, reducing surface tension between two surfaces as how a surfactant molecule is able to achieve. This review paper aims to provide a comprehensive study on the recent advances in bacteria cultivation for glycolipids production and current lab scale applications of glycolipids (e.g., medical and waste bioremediation). Studies have proven that glycolipids are effective anti-microbial agents, subsequently leading to an excellent anti-biofilm forming agent. Heavy metal and hydrocarbon contaminated soil can also be bioremediated via the use of glycolipids. The major hurdle in the commercialization of glycolipid production is that the cultivation stage and downstream extraction stage of the glycolipid production process induces a very high operating cost. This review provides several solutions to overcome this issue for glycolipid production for the commercialization of glycolipids (e.g., developing new cultivating and extraction techniques, using waste as cultivation medium for microbes and identifying new strains for glycolipid production). The contribution of this review aims to serve as a future guideline for researchers that are dealing with glycolipid biosurfactants by providing an in-depth review on the recent advances of glycolipid biosurfactants. By summarizing the points discussed as above, it is recommended that glycolipids can substitute synthetic surfactants as an environmentally friendly alternative.

In recent years, researchers have proven that the employment of natural green components in the biogenesis of nanoparticles from microalgae species is one of the ways to delight the global environment issues. The application of nanotechnology with the exploitation of phycochemical produced from algae species is known as 'phyconanotechnology'. The use of biological compounds by microalgae as reducing agents for the synthesis of inorganic nanoparticles has shown promising results such as cost-effective and environmentally friendly. Different classifications of algae such as brown algae, red algae, green algae, and cyanobacteria are studied for the synthesis of different types of metal nanoparticles. It is also an important motive to acknowledge the mechanisms of the microalgae-mediated biosynthesis of nanoparticles via an intracellular pathway or extracellular pathway. Besides, microalgae species as biogenic sources preclude the use of conventional methods reagents, such as sodium borohydride (NaBH4) and N,N-dimethylformamide (DMF), which further consolidates their position as the best choice for sustainable (economically and environmentally) nanoparticle synthesis compared to the conventional nanoparticles synthesis pathway.

The litter of persistent organic pollutants (POPs) into the water streams and soil bodies via industrial effluents led to several adverse effects on the environment, health, and ecosystem. For the past decades, scientists have been paying efforts in the innovation and development of POPs removal from wastewater treatment. However, the conventional methods used for the removal of POPs from wastewater are costly and could lead to secondary pollution including soil and water bodies pollution. In recent, the utilization of green mechanisms such as biosorption, bioaccumulation and biodegradation has drawn attention and prelude the potential of green technology globally. Microalgae-bacteria consortia have emerged to be one of the latent wastewater treatment systems. The synergistic interactions between microalgae and bacteria could proficiently enhance the existing biological wastewater treatment system. This paper will critically review the comparison of conventional and recent advanced wastewater treatment systems and the mechanisms of the microalgae-bacteria symbiosis system.