World journal of microbiology & biotechnology最新文献

Biogas is a renewable energy source produced through the anaerobic digestion of organic waste. Access by microbial enzymes can be facilitated if the lignocellulosic material undergoes pretreatment. Leaf litter and termite guts can be promising sources of enzyme-producing microorganisms for this purpose. Fungi and bacteria recovered from soil litter and termite guts were screened for enzymatic activities and used as a consortium in a pretreatment of sugarcane bagasse to improve biogas production. Forty fungi and nine bacteria were isolated. From this, nine filamentous fungi and nine bacteria produced at least two of the enzymatic activities. The highest values ​for laccase, lignin peroxidase, and manganese peroxidase were 0.16, 1,863.80, and 1,737.27 U L⁻¹, respectively. For cellulase and xylanase were 13.52 and 64.24 U mL⁻¹, respectively. Talaromyces mycothecae BR04, Aspergillus versicolor BR14, Rossellomorea marisflavi CPM2, Bacillus subtilis CPM6, and Priestia megaterium CPM18 were used in the pretreatment of sugarcane in semi-solid fermentation for 14 days at 28 °C, due to improved performance in enzymatic activities and compatibility assays. Sugarcane bagasse + bacteria (SCB + B) treatment exhibited the highest total accumulated biogas production, reaching 66.95 NL kg^- 1 VS, compared to SCB, demonstrating that microbial pretreatment improved biogas production. Fungi and bacteria isolated from leaf litter and termite guts produce enzymes involved in biogas production. The use of microbial consortia in the pretreatment of lignocellulosic biomass can enhance biogas production.

The persimmon (Diospyros kaki L.) is used in folk medicine, pharmaceuticals and cosmetics. It has several reported benefits, including antibacterial and antibiofilm properties. This study focused on investigating potential active compounds of fresh persimmon extract against test bacteria (Acinetobacter pittii, Acinetobacter baumannii and Pseudomonas aeruginosa) isolated from diabetic foot (DF) patients regarding antibacterial and antibiofilm activities. Accordingly, antibacterial, antibiofilm and cellular proliferation abilities for PCS-201-102 human dermal fibroblast cell line of extracts were determined. The chemical compounds of extracts were determined by Q-TOF-MS Accurate-Mass. Eleven molecules according to the negative ESI mode and seven molecules according to the positive ESI mode were selected. The selected compounds were analyzed for binding affinities to biofilm associated OmpA protein (for A. baumannii and A. pittii) and the YfiBNR triple signal sequence (for P. aeruginosa), via in silico modelling. Then, these compounds with high binding energy were also tested in vitro for their antibacterial and antibiofilm properties. Although no significant antibacterial activity of extracts has been recorded, high results (80.80-68.61%) have been observed for antibiofilm activity. The extracts did not show toxicity. Aesculin and rutin demonstrated high binding energy to the relevant proteins. Aesculin inhibited biofilm formation by A. pittii (76.18%), A. baumannii (81.88%) and P. aeruginosa (75.25%), while rutin was also over 75% effective against A. baumannii (79.29%) and P. aeruginosa (75.64%). Considering the crucial role of biofilm structure in worsening the clinical course of DF, aesculin and rutin have the potential to be used as adjuvants in combination with other ingredients/antibiotics.

To investigate the intrinsic potential of oil-contaminated saline soils for degrading aromatic hydrocarbons, a halotolerant bacterial strain identified as Planococcus antioxidans PAB314 was isolated and characterized for its hydrocarbon-degrading ability. The genome of P. antioxidans PAB314 was sequenced using next-generation techniques, uncovering a 3,705,003 bp genome with 3,263 coding DNA sequences. Gene ontology analysis identified 2,423 genes, highlighting predominant functions in amino acid transport, metabolism, and general cellular processes. GC-MS analysis of naphthalene degradation revealed salicylate and catechol as breakdown products, consistent with established bacterial degradation pathways. Anthracene degradation produced 3-hydroxy-2-naphthoic acid, 6,7-benzocoumarin, and cis-4-(2-hydroxy-3-naphthyl)-2-oxobut-3-enoate, consistent with documented pathways. Pyrene degradation yielded phenanthrene-4,5-dicarboxylate, phenanthrene-4-carboxylate, 1-hydroxy-2-naphthoic acid, and phthalate, suggesting an initial dioxygenation or monooxygenation at the C-4 and C-5 positions to form hydroxylated intermediates, followed by ring cleavage and decarboxylation. Catabolic genes like alcohol dehydrogenase, ring-cleaving dioxygenase, catechol-2,3-dioxygenase, and aldehyde dehydrogenase were found within the genome, indicating P. antioxidans PAB314's genetic capability to degrade polycyclic aromatic hydrocarbons. This study introduces Planococcus antioxidans PAB314 as a novel halotolerant strain capable of efficiently utilizing and degrading aromatic hydrocarbons with diverse ring structures under high-salinity conditions, providing genomic and biochemical evidence of its degradation potential and underscoring its ecological significance and applicability in the bioremediation of hydrocarbon-contaminated saline environments.

Limonene is a naturally occurring monocyclic monoterpene that is a substrate for the sustainable production of high-value bioactive compounds for green chemistry, perfumes, cosmetics, and pharmaceuticals. Despite being promising, the application of limonene industrially is limited because of its high volatility, low solubility, and cytotoxic action towards microbial hosts. Value-added compounds such as carveol, carvone, perillyl alcohol, perillic acid, and limonene-1,2-diol are produced from limonene through microbial biotransformation. This review explores the role of bacteria, yeast, and fungi in these bioconversions, detailing key enzymatic reactions like hydroxylation, oxidation, epoxidation, and dihydroxylation. The influence of limonene enantiomers on product formation and specificity of biotransformation is discussed, along with applications of the resulting compounds in therapeutic, aromatic, and industrial domains. It also summarizes current challenges and future opportunities for industrial-scale production, including substrate and product toxicity, limitations of enzymatic reaction, and process scalability. On comparison with earlier reviews that addressed the biological and industrial aspects of limonene separately, this review provides a comprehensive approach that combines metabolic engineering, biosynthesis, microbial biotransformation, and therapeutic potential. It also emphasizes chemoenzymatic methodologies, providing a thorough framework that links biomedical applications with green bioprocessing and highlights new prospects for the industrial valorization of limonene and its derivatives.

Malachite green, a carcinogenic triphenylmethane dye. In this study, Pseudomonas sp. C2-4 was isolated, and both free and immobilized forms of this bacterium demonstrated high decolorization capacity. The free cells were able to remove 100 mg/L and 1000 mg/L of malachite green within 48 h, achieving efficiencies of 99.68% ± 0.26 and 85.32% ± 2.00, respectively, and maintained over 90.12% ± 3.15 efficiency between 28 and 40 °C and pH 6.0-10.0. After immobilization, the strain exhibited enhanced environmental adaptability, achieving over 87% efficiency under broader conditions (15-45 °C, pH 3.0-10.0, 1-5% NaCl) and retaining 94.57% ± 1.60 efficiency after five reuse cycles. Among metal ions, Ca²⁺ promoted degradation, Cu²⁺ strongly inhibited it, while Mn²⁺, Mg²⁺, and Zn²⁺ showed negligible effects. Mechanism studies via Fourier Transform Infrared Spectroscopy and Gas Chromatography-Mass Spectrometry indicated that malachite green was removed through both biosorption (involving functional groups such as aliphatic nitro compounds, methyl C-H, carboxyl, and aromatic ethers) and biodegradation (yielding N, N-dimethylaniline, aniline, and benzoic acid). Phytotoxicity tests following treatment with either free or immobilized strain C2-4 confirmed effective detoxification, as evidenced by significant increase in Chinese cabbage seed germination rates, root length, and stem length. These results demonstrate the strain's exceptional decolorization and detoxification capabilities via both biosorption and biodegradation, with immobilization enhancing its effectiveness for treating dye-contaminated wastewater under diverse conditions, highlighting its significant potential for practical application.

Delta-endotoxins are produced by Bacillus thuringiensis (Bt) and have their main application in agriculture to manage insect crops and as antimicrobial. Its large scale production is limited by oxygen availability during Bt fermentation since delta-endotoxin synthesis requires high oxygen level. Therefore, it requires the enhancement of the agitation speed and air flow rate, which could be solved by adding an oxygen vector. So, the objective was to evaluate the use of oxygen vectors (soybean, corn and sunflower oil) on the enhancement of delta-endotoxin production and its toxicity against Spodoptera frugiperda and pathogenic microorganisms. In this way, the effects of oils on fermentation were studied from a 2⁴ full experimental design, where their concentration varied from 0% to 3%. Posteriorly, the best oil and concentration to produce delta-endotoxin was studied in a 7.5 L agitated tank bioreactor. The experimental design revealed that corn oil (3%) and sunflower oil (3%) could significantly enhance delta-endotoxin production, and this combination was considered the best condition to produce delta-endotoxins. In addition, kinetics parameters like X_m, P_x, µ_X.max and µ_S.max were increased in comparison to a fermentation without oxygen vector. Delta-endotoxins produced in the presence of oils showed higher activity against S. frugiperda and bacteria isolated from goat mastitis. Therefore, this research demonstrates that corn and sunflower oils can serve as oxygen vectors, enhancing both the production of delta-endotoxins and their toxicity against pathogenic bacteria and Lepidopterans.

Cyanobacterial exopolysaccharides (EPS) are natural biopolymers with substantial applications in the nutraceutical and food industries. This work included the isolation of a freshwater cyanobacterium, Leptolyngbya sp. MKU-05, and the optimization of its exopolysaccharide synthesis by response surface methodology. A central composite rotatable design yielded a maximum EPS production of 567.3mg L^- 1 under optimized medium conditions. The ExoD paralogs have a direct impact on EPS synthesis, as gene expression analysis demonstrated a 4.5-fold increase in the EPS biosynthetic gene ExoD2 relative to unoptimized conditions. Partial structural characterization of purified EPS was deduced using Fourier-Transform Infrared Spectroscopy (FTIR) and Nuclear Magnetic Resonance (NMR) analysis were used to partially characterize the structure of purified EPS and validate the presence of carboxyl, hydroxyl, and amide functional groups. Monosaccharide profiling indicated arabinose as a major component. SEM and XRD analyses revealed a fibrous, porous, and semi-crystalline nature of the EPS structure. Functionally, the EPS exhibited significant anti-inflammatory and antioxidant activities compared to the commercial drug mesalazine. Toxicological assessments using human embryonic kidney cells (HEK293 cells), human erythrocytes, and Artemia nauplii confirmed the non-toxic nature of the EPS. Notably, the EPS promoted cell proliferation and improved A. nauplii survival, further supporting its biocompatibility and safety. Collectively, the EPS from Leptolyngbya sp. MKU-05 EPS is a multifunctional and safe biopolymer with promising therapeutic and nutraceutical applications.

Combinatorial engineering strategies were performed to improve cellulase production efficiencies of Aspergillus niger. Single functional cellulases in Aspergillus niger were knocked out with the exogenous multifunctional cellulases. Non-cellulase enzymes of phytase, β-mannanase and pectinase were deleted out from Aspergillus niger. The exogenous protein disulfide isomerase was expressed in Aspergillus niger. The cellulase activities from the reconstructed Aspergillus niger increased from 0.62 U/mL to 7.96 U/mL. Glucose released from corn stover increased from 12.5 g/L to 27.8 g/L. Deleting non-cellulase enzymes, expressing the multifunctional cellulase and exogenous protein disulfide isomerase could enhance cellulase production efficiencies of Aspergillus niger.