Bacillus cereus saba.zh, a novel bacterial strain for the production of bioplastic (polyhydroxybutyrate)

Molybdenum tolerance of strains screened from molybdenum tailings and their potential application in molybdenum-contaminated soils

Mining and smelting activities of molybdenum (Mo) have led to increasingly severe Mo pollution in the environment, posing potential threats to ecosystems and human health. Microbial remediation technology has emerged as an effective approach for reducing Mo pollution due to its environmental friendliness and cost-effectiveness. In this study, two Mo (Ⅵ) tolerant strains (MoTB 2 and MoTB 79) with exceptional Mo reduction capacities were isolated and identified from the rhizosphere soil of pioneer plants in Mo-contaminated tailings. Systematic studies were conducted to evaluate their Mo tolerance, reduction efficiency, and underlying mechanisms in both controlled and soil environments. The results showed that both strains exhibited robust growth in high-Mo (VI) conditions (6000 mg L-1), comparable to Mo-free environments, with optimal growth observed at pH 5.0 and 30°C. Notably, under conditions of 5.0 mmol L-1 phosphate and 60.0 mmol L-1 molybdate, the strains demonstrated significant Mo (Ⅵ) removal capabilities (14.8%-22.5% within 24 h) via bioconversion to molybdate. Further mechanistic analysis using a multi-technique approach revealed that FTIR spectroscopy identified phosphate groups, amide bonds, C-O-C, and -CH groups as key functional entities for extracellular Mo (Ⅵ) adsorption, while TEM-EDX confirmed intracellular bioaccumulation. Critically, XPS quantification demonstrated valence state transformations, with 79.8%-86.3% of toxic Mo (Ⅵ) reduced to less toxic Mo (Ⅳ) (23.4%-39.7%) and Mo (Ⅴ) (40.1%-63.0%). To bridge laboratory findings with environmental applications, soil remediation experiments revealed an 11.8%-19.6% conversion of mobile Mo (Ⅵ) to immobilized Mo (0) and Mo (Ⅳ) fractions via XANES, effectively passivating bioavailable Mo. Notably, the strains also exhibited phosphate/potassium solubilization capabilities, suggesting dual roles in metal detoxification and nutrient cycling. This integrated study elucidates the potential of MoTB strains as eco-engineers for bioremediation in Mo-contaminated ecosystems through adsorption, bioaccumulation, multi-valence reduction, and soil fertility enhancement.

Development of Biodegradable Bioplastics with Sericin and Gelatin from Silk Cocoons and Fish Waste

The bioplastics sector promotes environmentally friendly means of cutting down on the usage of fossil fuels, plastic waste, and environmental pollution. Plastic contamination has detrimental effects on both ecological systems and the global food supply. The approach we present here to resolve this issue involves the integration of sericin and gelatin, obtained from cocoon and fish waste, respectively, with nano-reinforced cellulose crystals, to develop a biodegradable and compostable plastic material. The use of cocoon and fish wastes for the extraction of sericin and gelatin presents an environmentally beneficial approach since it contributes to waste reduction. The sericin level found in silk cocoon waste was determined to be 28.08%, and the gelatin amount in fish waste was measured to be 58.25%. The inclusion of sericin and gelatin in bioplastics was accompanied by the incorporation of glycerol, vinegar, starch, sodium hydroxide, and other coloring agents. Fourier transform infrared (FTIR) examination of bioplastics revealed the presence of functional groups that corresponded to the sericin and gelatin components. The tensile strength of the bioplastic material was measured to be 27.64 MPa/psi, while its thickness varied between 0.072 and 0.316 mm. The results of burial experiments indicated that the bioplastic material had a degradation rate of 85% after 14 days. The invention exhibits potential as a viable alternative for packaging, containment, and disposable plastic materials. The use of this sustainable approach is recommended for the extraction of sericin and gelatin from silk cocoons and fish waste, with the intention of using them as raw materials for bioplastic production.

Alkaline-Tolerant Bacillus cereus 12GS: A Promising Polyhydroxybutyrate (PHB) Producer Isolated from the North of Mexico

Environmental pollution caused by petroleum-derived plastics continues to increase annually. Consequently, current research is interested in the search for eco-friendly bacterial polymers. The importance of Bacillus bacteria as producers of polyhydroxyalkanoates (PHAs) has been recognized because of their physiological and genetic qualities. In this study, twenty strains of Bacillus genus PHA producers were isolated. Production was initially evaluated qualitatively to screen the strains, and subsequently, the strain B12 or Bacillus sp. 12GS, with the highest production, was selected through liquid fermentation. Biochemical and molecular identification revealed it as a novel isolate of Bacillus cereus. Production optimization was carried out using the Taguchi methodology, determining the optimal parameters as 30 °C, pH 8, 150 rpm, and 4% inoculum, resulting in 87% and 1.91 g/L of polyhydroxybutyrate (PHB). Kinetic studies demonstrated a higher production within 48 h. The produced biopolymer was analyzed using Fourier-transform infrared spectroscopy (FTIR), confirming the production of short-chain-length (scl) polyhydroxyalkanoate, named PHB, and differential scanning calorimetry (DSC) analysis revealed thermal properties, making it a promising material for various applications. The novel B. cereus isolate exhibited a high %PHB, emphasizing the importance of bioprospecting, study, and characterization for strains with biotechnological potential.

Organic waste-to-bioplastics: Conversion with eco-friendly technologies and approaches for sustainable environment

Petrochemical-based synthetic plastics poses a threat to humans, wildlife, marine life and the environment. Given the magnitude of eventual depletion of petrochemical sources and global environmental pollution caused by the manufacturing of synthetic plastics such as polyethylene (PET) and polypropylene (PP), it is essential to develop and adopt biopolymers as an environment friendly and cost-effective alternative to synthetic plastics. Research into bioplastics has been gaining traction as a way to create a more sustainable and eco-friendlier environment with a reduced environmental impact. Biodegradable bioplastics can have the same characteristics as traditional plastics while also offering additional benefits due to their low carbon footprint. Therefore, using organic waste from biological origin for bioplastic production not only reduces our reliance on edible feedstock but can also effectively assist with solid waste management. This review aims at providing an in-depth overview on recent developments in bioplastic-producing microorganisms, production procedures from various organic wastes using either pure or mixed microbial cultures (MMCs), microalgae, and chemical extraction methods. Low production yield and production costs are still the major bottlenecks to their deployment at industrial and commercial scale. However, their production and commercialization pose a significant challenge despite such potential. The major constraints are their production in small quantity, poor mechanical strength, lack of facilities and costly feed for industrial-scale production. This review further explores several methods for producing bioplastics with the aim of encouraging researchers and investors to explore ways to utilize these renewable resources in order to commercialize degradable bioplastics. Challenges, future prospects and Life cycle assessment of bioplastics are also highlighted. Utilizing a variety of bioplastics obtained from renewable and cost-effective sources (e.g., organic waste, agro-industrial waste, or microalgae) and determining the pertinent end-of-life option (e.g., composting or anaerobic digestion) may lead towards the right direction that assures the sustainable production of bioplastics.