Probing role of key residues in the divergent evolution of Yarrowia lipolytica lipase 2 and Aspergillus niger eruloyl esterase A

Three strategy rules of filamentous fungi in hydrocarbon remediation: an overview

Remediation of hydrocarbon contaminations requires much attention nowadays since it causes detrimental effects on land and even worse impacts on aquatic environments. Tools of bioremediation especially filamentous fungi permissible for cleaning up as much as conceivable, at least they turn into non-toxic residues with less consumed periods. Inorganic chemicals, CO2, H2O, and cell biomass are produced as a result of the breakdown and mineralization of petroleum hydrocarbon pollutants. This paper presents a detailed overview of three strategic rules of filamentous fungi in remediating the various aliphatic, and aromatic hydrocarbon compounds: utilizing carbons from hydrocarbons as sole energy, Co-metabolism manners (Enzymatic and Non-enzymatic theories), and Biosorption approaches. Upliftment in the degradation rate of complex hydrocarbon by the Filamentous Fungi in consortia scenario we can say, "Fungal Talk", which includes a variety of cellular mechanisms, including biosurfactant production, biomineralization, and precipitation, etc., This review not only displays its efficiency but showcases the field applications - cost-effective, reliable, eco-friendly, easy to culture as biomass, applicable in both land and any water bodies in operational environment cleanups. Nevertheless, the potentiality of fungi-human interaction has not been fully understood, henceforth further studies are highly endorsed with spore pathogenicity of the fungal species capable of high remediation rate, and the gene knockout study, if the specific peptides cause toxicity to any living matters via Genomics and Proteomics approaches, before application of any in situ or ex situ environments.

A Novel Lipase from Streptomyces exfoliatus DSMZ 41693 for Biotechnological Applications

Genome mining of Streptomyces exfoliatus DSMZ 41693 has allowed us to identify four different lipase-encoding sequences, and one of them (SeLipC) has been successfully cloned and extracellularly expressed using Rhodococcus sp. T104 as a host. SeLipC was purified by one-step hydrophobic interaction chromatography. The enzyme is a monomeric protein of 27.6 kDa, which belongs to subfamily I.7 of lipolytic enzymes according to its phylogenetic analysis and biochemical characterization. The purified enzyme shows the highest activity at 60 °C and an optimum pH of 8.5, whereas thermal stability is significantly improved when protein concentration is increased, as confirmed by thermal deactivation kinetics, circular dichroism, and differential scanning calorimetry. Enzyme hydrolytic activity using p-nitrophenyl palmitate (pNPP) as substrate can be modulated by different water-miscible organic cosolvents, detergents, and metal ions. Likewise, kinetic parameters for pNPP are: KM = 49.6 µM, kcat = 57 s-1, and kcat/KM = 1.15 × 106 s-1·M-1. SeLipC is also able to hydrolyze olive oil and degrade several polyester-type polymers such as poly(butylene succinate) (PBS), poly(butylene succinate)-co-(butylene adipate) (PBSA), and poly(ε-caprolactone) (PCL). Moreover, SeLipC can catalyze the synthesis of different sugar fatty acid esters by transesterification using vinyl laurate as an acyl donor, demonstrating its interest in different biotechnological applications.

Fabrication of Co3O4-Bi2O3-Ti catalytic membrane for efficient degradation of organic pollutants in water by peroxymonosulfate activation

In this study, a functionalized Co₃O₄-Bi₂O₃-Ti catalytic membrane (CBO-Ti-M) was prepared and applied for removing organic pollutants via activating peroxymonosulfate (PMS) in the dead-end filtration mode. Characterizations including scanning electron microcopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) showed that the Co₃O₄-Bi₂O₃ catalyst was successfully supported on the Ti membrane. The CBO-Ti-M /PMS system could efficiently remove various organic pollutants such as sulfamethoxazole, methyl orange, bisphenol A and methylene blue, achieving removal efficiencies of 98.0%-99.5%. The effects of PMS concentration, flow rate and solution environment on degradation efficiency were investigated in detail. Furthermore, quenching experiments, electron spin resonance (ESR) and in-situ open circuit potential (OCP) tests collectively demonstrated that singlet oxygen as well as the non-radical electron transfer pathway mainly contributed in the reaction mechanism. The synergistic effect of Co and Bi was illustrated according to XPS results, and the possible degradation pathway of MB was proposed based on LC-MS analysis. Reusability test showed that pollutant removal efficiency with the CBO-Ti-M /PMS system remained stable in four runs and limited metal leaching was observed.

Leading edges in bioremediation technologies for removal of petroleum hydrocarbons

There is a worldwide concern regarding soil pollution caused by contamination of petroleum hydrocarbon, released during oil processing or production. Once a spill occurs, it disturbs the marine and freshwater ecosystem and greatly threatens human health. It usually requires complex technologies to remove it from soil. Petroleum hydrocarbons contain a range of chemicals which are extremely toxic and carcinogenic in nature. Although physical or chemical methods are widely employed for remediation, numerous studies revealed that bioremediation is a sustainable approach. Bioremediation is often preferred as clean and carbon-neutral solution. This review aims to provide series of sustainable solution for petroleum hydrocarbon degradation without exploiting the environment as well as opportunity to reuse treated media. Integrated and enhanced bioremediation technologies are more effective than natural degradation of petroleum hydrocarbons in terms of shorter time period and percent removal efficiency. It comprehensively illustrates bioremediation assisted with bacteria, fungi, and algae either by integrated technologies or by enhancing the process. Most recent application methods of petroleum hydrocarbon bioremediation (in situ and ex situ) are also reported. There is dire need to explore different cost-effective biotechnological resources for degradation of petroleum hydrocarbon by the screening of novel microbial strains or by the creation of genetically engineered bacteria to survive in harsh environment.

Enhancing thermostability of Yarrowia lipolytica lipase 2 through engineering multiple disulfide bonds and mitigating reduced lipase production associated with disulfide bonds

The limited thermostability of Yarrowia lipolytica lipase 2 (Lip2) hampers its industrial application. To improve its thermostability, we combined single disulfide bonds which our group identified previously. In this study, combining different regional disulfide bonds had greater effect than combining same regional disulfide bonds. Furthermore, mutants with 4, 5, and 6 disulfide bonds exhibited dramatically enhanced thermostability. Compared with the wild-type, sextuple mutant 6s displayed a 22.53 and 31.23 ℃ increase in the melting temperature (T_m) and the half loss temperature at 15 min (T15 50), respectively, with greater pH stability and a wider reaction pH range. Molecular dynamics simulation revealed that multiple disulfide bonds resulted in more rigid structures of mutants 4s, 5s and 6s, and prolonged enzyme unfolding times. Moreover, secretions of mutants 5s and 6s were significantly increased by 60% and 80% by co-expressing with the chaperone protein disulfide isomerase (PDI), which mitigated the reduced production issue caused by multiple disulfide bonds. Results of this study indicated that enhanced heat endurance giving more potential for industrial application.