Biosynthesis and biodegradation of poly(3-hydroxybutyrate) from Priestia flexa; A promising mangrove halophyte towards the development of sustainable eco-friendly bioplastics

Bioprospecting amylase from Samiti Lake, situated in the eastern Himalayas

Enzymes, especially amylases, have been an economic boon to the industrial sector, their bioprospective and biotechnological use is an added advantage. Our primary focus of the study was to isolate the most potent amylase producer and to optimize its production parameters through One Factor At A Time (OFAT), Central Composite Rotatable Design Response Surface Methodology (CCRD RSM) and Artificial Neural Network (ANN). Based on the qualitative and quantitative analysis, SLAB1 was selected as the most potent amylase producer out of the potential isolates. Further SLAB1 was identified as Priestia flexa via 16SrRNA identification. Optimization of the production parameters showed the best carbon, nitrogen sources, temperature and pH to be fructose, peptone, 20 °C and pH 8.0 respectively. Further, the enzyme was purified using ammonium sulphate precipitation followed by dialysis. Later, DEAE Sepharose (Sigma) resin was used for ion exchange chromatography and the protein was eluted using NaCl gradients from 0.1 M - 0.6 M. Enzyme kinetics assessment of the purified amylase with the Lineweaver Burk plot showed values of maximum rate; Vmax (10.869 μmoL/min), and Michaelis-Menten constant Km to be around (14.91 mg/ml). To determine its potential application, analysis of this purified amylase in cleaning the tomato and chocolate stained cotton fabrics after comparing its compatibility with different detergents were executed. Further analysis of the washed stained fabrics via Scanning Electron Microscopy was carried out.

Biodegradable polymer films incorporating phycocyanin and polyhydroxybutyrate: advancing sustainable packaging technologies

The biocompatibility and degradability of poly hydroxybutyrate (PHB) make it an important material for food packaging. Poly hydroxybutyrate (PHB) is less flexible than typical polymers and more brittle due to its strong crystalline structure and low melting temperature. Furthermore, while poly hydroxybutyrate (PHB) does not have antibiotic capabilities, the inclusion of additional materials such as phycocyanin can boost its antibiotic and antifungal effects. This research focuses on increasing the yield of phycocyanin from the microalgae Spirulina and selecting an optimal green extraction method, and on the other hand, on the synthesis of biodegradable polymers derived from poly hydroxybutyrate in combination with phycocyanin for food packaging applications. This study shows that higher wavelengths of light, an optimal temperature of about 33 degrees Celsius, pH adjustments using changing the composition of the culture medium by increasing metal compounds and using non-invasive, green and inexpensive extraction methods significantly increase biomass production and phycocyanin yield, which in previous research only one to two of the above parameters were considered for protein extraction, which this study has addressed more comprehensively. Also, the synthesis of biodegradable polymers with special properties for packaging applications, including green polymer poly hydroxybutyrate, phycocyanin and beeswax, which has not been done in previous research on modifying the properties of poly hydroxybutyrate using these two research materials, so that with 60% phycocyanin in combination with poly hydroxybutyrate, they show promising properties for food packaging applications. By examining the physical and chemical properties, thermal strength and degradability of the polymer compared to pure poly hydroxybutyrate, it shows further improvement in addition to antibiotic and antifungal properties.

Review on Biodegradable Aliphatic Polyesters: Development and Challenges

Biodegradable polymers are gaining attention as alternatives to non-biodegradable plastics to address environmental issues. With the rising global demand for plastic products, the development of non-toxic, biodegradable plastics is a significant topic of research. Aliphatic polyester, the most common biodegradable polyester, is notable for its semi-crystalline structure and can be synthesized from fossil fuels, microbial fermentation, and plants. Due to great properties like being lightweight, biodegradable, biocompatible, and non-toxic, aliphatic polyesters are used in packaging, medical, agricultural, wearable devices, sensors, and textile applications. The biodegradation rate, crucial for biodegradable polymers, is discussed in this review as it is influenced by their structural properties and environmental conditions. This review discusses currently available biodegradable polyesters, their emerging applications, and the challenges in their commercialization. As research in this area grows, this review emphasizes the innovation in biodegradable aliphatic polyesters and their role in advancing environmental sustainability.

Halotolerant Endophytic Bacteria Priestia flexa 7BS3110 with Hg2+ Tolerance Isolated from Avicennia germinans in a Caribbean Mangrove from Colombia

The mangrove ecosystems of the Department of Atlántico (Colombian Caribbean) are seriously threatened by problems of hypersalinization and contamination, especially by heavy metals from the Magdalena River. The mangrove plants have developed various mechanisms to adapt to these stressful conditions, as well as the associated microbial populations that favor their growth. In the present work, the tolerance and detoxification capacity to heavy metals, especially to mercury, of a halotolerant endophytic bacterium isolated from the species Avicennia germinans located in the Balboa Swamp in the Department of Atlántico was characterized. Diverse microorganisms were isolated from superficially sterilized A. germinans leaves. Tolerance to NaCl was evaluated for each of the obtained isolates, and the most resistant was selected to assess its tolerance to Pb2+, Cu2+, Hg2+, Cr3+, Co2+, Ni2+, Zn2+, and Cd2+, many of which have been detected in high concentrations in the area of study. According to the ANI and AAI percentages, the most halotolerant strain was identified as Priestia flexa, named P. flexa 7BS3110, which was able to tolerate up to 12.5% (w/v) NaCl and presented a minimum inhibitory concentrations (MICs) of 0.25 mM for Hg, 10 mM for Pb, and 15 mM for Cr3+. The annotation of the P. flexa 7BS3110 genome revealed the presence of protein sequences associated with exopolysaccharide (EPS) production, thiol biosynthesis, specific proteins for chrome efflux, non-specific proteins for lead efflux, and processes associated with sulfur and iron homeostasis. Scanning electron microscopy (SEM) analysis showed morphological cellular changes and the transmission electron microscopy (TEM) showed an electrodense extracellular layer when exposed to 0.25 mM Hg2+. Due to the high tolerance of P. flexa 7BS3110 to Hg2+ and NaCl, its ability to grow when exposed to both stressors was tested, and it was able to thrive in the presence of 5% (w/v) NaCl and 0.25 mM of Hg2+. In addition, it was able to remove 98% of Hg2+ from the medium when exposed to a concentration of 14 mg/L of this metalloid. P. flexa 7BS3110 has the potential to bioremediate Hg2+ halophilic contaminated ecosystems.

Priestia flexa as a Novel Urinary Tract Pathogen in Daloa, Côte d'Ivoire: Insights From Genomic Sequencing

Bacterial strains coded 21LM367, 21LM07, and 21LM1136 were isolated from the urine of patients with urinary tract infections (UTIs) at the Centre Hospitalier Régional de Daloa in Côte d'Ivoire. Based on average nucleotide identity (ANI) analysis, DNA-DNA digital hybridisation (dDDH), and other comparative genomic methods, strains 21LM07, 21LM367, and 21LM1136 were determined to be Priestia flexa. The size of the assembled complete genomes ranged from 8,624,538 to 4,007,501 bp. The average GC content was 37.76%, 46.33%, and 43.03% for strains 21LM07, 21LM367, and 21LM1136, respectively. The total number of coding regions (CDS) in each genome was 4172, 8497, and 6795, respectively, for strains 21LM07, 21LM367, and 21LM1136. Genomic prediction analysis revealed that a total of 4241, 8583, and 6881 genes were annotated in the 21LM07, 21LM367, and 21LM1136 genomes, respectively. No virulence or resistance genes were predicted in the genomes of strains 21LM07 and 21LM1136. On the other hand, two genes conferring resistance to beta-lactam and tetracyclines as well as nine virulence genes were predicted in the genome of 21LM367. In addition, 438, 350, and 153 mobile genetic elements (MGEs) were predicted in the genomes of strains 21LM367, 21LM1136, and 21LM07, respectively. Strain 21LM07 was characterised by the absence of plasmids in its genome. Two plasmids were predicted in the genomes of isolates 21LM367 and 21LM1136; however, rep7a and IncI2 were predicted to contain the tet(K) resistance gene. No typical multilocus sequences could be characterised in the genomes of the different strains.

Synergistic approach for enhanced production of polyhydroxybutyrate by Bacillus pseudomycoides SAS-B1: Effective utilization of glycerol and acrylic acid through fed-batch fermentation and its environmental impact assessment

The continual rise in the consumption of petroleum-based synthetic polymers raised a significant environmental concern. Bacillus pseudomycoides SAS-B1 is a gram-positive rod-shaped halophilic bacterium capable of accumulating Polyhydroxybutyrate (PHB)-an intracellular biodegradable polymer. In the present study, the optimal conditions for cell cultivation in the seed media were developed. The optimal factors included a preservation age of 14 to 21 days (with 105 to 106 cells/mL), inoculum size of 0.1 % (w/v), 1 % (w/v) glucose, and growth temperature of 30 °C. The cells were then cultivated in a two-stage fermentation process utilizing glycerol and Corn Steep Liquor (CSL) as carbon and nitrogen sources, respectively. PHB yield was effectively increased from 2.01 to 9.21 g/L through intermittent feeding of glycerol and CSL, along with acrylic acid. FTIR, TGA, DSC, and XRD characterization studies were employed to enumerate the recovered PHB and determine its physicochemical properties. Additionally, the study assessed the cradle-to-gate Life Cycle Assessment (LCA) of PHB production, considering net CO2 generation and covering all major environmental impact categories. The production of 1000 kg of PHB resulted in lower stratospheric ozone depletion and comparatively reduced carbon dioxide emissions (2022.7 kg CO2 eq.) and terrestrial ecotoxicity (9.54 kg 1,4-DCB eq.) than typical petrochemical polymers.