Expression of exo-inulinase gene from Aspergillus niger 12 in E. coli strain Rosetta-gami B (DE3) and its characterization

Insights in inulin binding and inulin oligosaccharide formation by novel multi domain endo-inulinases from Botrytis cinerea

World-wide, pathogenic fungi such as Botrytis cinerea cause tremendous yield losses in terms of food production and post-harvest food decay. Many fungi produce inulin-type oligosaccharides (IOSs) from inulin through endo-inulinases which typically show a two domain structure. B.cinerea lacks a two domain endo-inulinase but contains a three domain structure instead. Genome mining revealed three and four domain (d4) enzymes in the fungal kingdom. Here, three and two domain enzymes were compared in their capacity to produce IOSs from inulin. Hill kinetics were observed in three domain enzymes as compared to Michaelis-Menten kinetics in two domain enzymes, suggesting that the N-terminal extension functions as a carbohydrate binding module. Analysis of the IOS product profiles generated from purified GF6, GF12, GF16 and GF18 inulins and extensive sugar docking approaches led to enhanced insights in the active site functioning, revealing subtle differences between the endo-inulinases from Aspergillus niger and B. cinerea. Improved insights in structure-function relationships in fungal endo-inulinases offer opportunities to develop superior enzymes for the production of specific IOS formulations to improve plant and animal health (priming agents, prebiotics).

Single substitution in α-helix of active center enhanced thermostability of Aspergillus awamori exo-inulinase

Exo-inulinases are applied in inulin hydrolysis and production of feed additives and need to be stable at temperatures of 60-95 °C. Aspergillus awamori exo-inulinase Inu1 is considerably thermostable, with a T_m of 73.2 °C. However, the thermostability of the enzyme should be improved. A single substitution G338A in α-helix in the active center of the enzyme provided a 3.5 °C improvement in T_m. The time of half-life at 70 °C and 80 °C was increased in 5.7- and 2.7-times, respectively, compared to wild-type. Molecular dynamics simulations demonstrated that the substitution G338A caused a decrease in RMSF not only for the α-helix 337-YAANI-341, but also for the catalytically active residues D41 and E241 and the amino acid residues forming the cleft of the active center. Calculations with Constraint Network Analysis for the variant G338A showed the increase in the stability of intramolecular clusters.

Production, purification, and characterization of inulinase from Streptomyces anulatus

Inulinase is an enzyme that catalyzes inulin to d-fructose. This enzyme can be extracted from plants, but it is difficult to obtain it in large quantities, so its production cost is high. Therefore, microbial inulinase has great potential for industrial needs. In the last decade, there have been very few reports on actinobacterial inulinases, especially on purification and characterization of inulinase process extraction. This study aims to select actinomycetes that possess high inulinase activity from the soil. To screen inulinase-producing bacteria, modified Czapex-Dox agar supplemented with 1% inulin powder was used. The most effective isolate was Streptomyces sp. EFBO8, morphological and genotypic identification methods, confirmed that the strain is Streptomyces anulatus and that its nucleotide sequence has been deposited in GenBank under accession number OQ073700. To optimize inulinase production, kinetics were performed by using S. anulatus strain, which proved to be most productive with a value of 24,024 EU/mL. The enzyme was purified from the culture filtrate by precipitation with ammonium sulfate (NH₄ )₂ SO₄ , followed by column chromatography Sephadex (G-50) separation. Purified protein has a molecular mass of 3331.83 Da.

Novel insights into construct toxicity, strain optimization, and primary sequence design for producing recombinant silk fibroin and elastin-like peptide in E. coli

Spider silk proteins (spidroins) are a remarkable class of biomaterials that exhibit a unique combination of high-value attributes and can be processed into numerous morphologies for targeted applications in diverse fields. Recombinant production of spidroins represents the most promising route towards establishing the industrial production of the material, however, recombinant spider silk production suffers from fundamental difficulties that includes low titers, plasmid instability, and translational inefficiencies. In this work, we sought to gain a deeper understanding of upstream bottlenecks that exist in the field through the production of a panel of systematically varied spidroin sequences in multiple E. coli strains. A restriction on basal expression and specific genetic mutations related to stress responses were identified as primary factors that facilitated higher titers of the recombinant silk constructs. Using these findings, a novel strain of E. coli was created that produces recombinant silk constructs at levels 4-33 times higher than standard BL21(DE3). However, these findings did not extend to a similar recombinant protein, an elastin-like peptide. It was found that the recombinant silk proteins, but not the elastin-like peptide, exert toxicity on the E. coli host system, possibly through their high degree of intrinsic disorder. Along with strain engineering, a bioprocess design that utilizes longer culturing times and attenuated induction was found to raise recombinant silk titers by seven-fold and mitigate toxicity. Targeted alteration to the primary sequence of the recombinant silk constructs was also found to mitigate toxicity. These findings identify multiple points of focus for future work seeking to further optimize the recombinant production of silk proteins and is the first work to identify the intrinsic disorder and subsequent toxicity of certain spidroin constructs as a primary factor related to the difficulties of production.

Estabelecimento de sistema bacteriano de expressão de peptídeos derivados da enzima vegetal RuBisCO

Resumo O objetivo do presente estudo foi estabelecer um sistema bacteriano de expressão de peptídeos derivados da proteólise simulada in silico da enzima ribulose-1,5-bisfosfato carboxilase oxigenase (RuBisCO), proveniente de soja, visando viabilizar um método sustentável de produção dessas moléculas para futura aplicação industrial. Inicialmente, foi conferida à cepa Escherichia coli S17-1 cálcio-competência para propagação do plasmídeo de expressão pET-30a(+) contendo o inserto codificante da sequência peptídica GSIKAFKEATKVDKVVVLWTALVPR. Após extração de DNA plasmidial, o material foi transformado em células de alto rendimento E. coli Rosetta™(DE3)pLysS. As células Rosetta portando o plasmídeo de expressão foram induzidas e a produção dos peptídeos foi verificada por meio de eletroforese em gel vertical, confirmando o estabelecimento de um sistema de expressão viável para peptídeos heterólogos. Assim, a produção em maior escala de peptídeos derivados de RuBisCO – associando-se futuramente etapas de purificação e ativação – torna-se possível. Além disso, o método aqui estabelecido pode também ser aplicado utilizando diferentes sequências peptídicas com atividade antimicrobiana.

Recent advances in bio-based multi-products of agricultural Jerusalem artichoke resources

The Jerusalem artichoke is a perennial plant that belongs to the sunflower family. As a non-grain crop, Jerusalem artichoke possesses a number of desirable characteristics that make it a valuable feedstock for biorefinery, such as inulin content, rapid growth, strong adaptability, and high yields. This review provides a comprehensive introduction to renewable Jerusalem artichoke-based biomass resources and recent advances in bio-based product conversion. Furthermore, we discuss the latest in the development of inulinase-producing microorganisms and enhanced inulin hydrolysis capacity of microbes by genetic engineering, which lead to a more cost-effective Jerusalem artichoke biorefinery. The review is aimed at promoting Jerusalem artichoke industry and new prospects for higher value-added production.