El-Sayed Mohamed H, Elsayed Doaa A, Gomaa Abd El-Rahman F
Department of Biology, College of Science and Arts, Northern Border University, Arar, Saudi Arabia.
Department of Botany and Microbiology, Faculty of Science, Al-Azhar University, Cairo 11884, Egypt.
AIMS Microbiol. 2024 Mar 12;10(1):187-219. doi: 10.3934/microbiol.2024010. eCollection 2024.
Actinomycetes are an attractive source of lignocellulose-degrading enzymes. The search for actinomycetes producing extremozyme cellulase using cheap lignocellulosic waste remains a priority goal of enzyme research. In this context, the extremophilic actinomycete NBRM9 showed promising cellulolytic activity in solid and liquid assays. This actinomycete was identified as based on its phenotypic characteristics alongside phylogenetic analyses of 16S rRNA gene sequencing (OQ380604.1). Using bean straw as the best agro-waste, the production of cellulase from this strain was statistically optimized using a response surface methodology, with the maximum activity (13.20 U/mL) achieved at an incubation temperature of 40 °C, a pH of 9, an incubation time of 7 days, and a 2% substrate concentration. The partially purified cellulase (PPC) showed promising activity and stability over a wide range of temperatures (20-90 °C), pH values (3-11), and NaCl concentrations (1-19%), with optimal activity at 50 °C, pH 9.0, and 10% salinity. Under these conditions, the enzyme retained >95% of its activity, thus indicating its extremozyme nature. The kinetics of cellulase showed that it has a V of 20.19 ± 1.88 U/mL and a Km of 0.25 ± 0.07 mM. The immobilized PPC had a relative activity of 69.58 ± 0.13%. In the in vitro microtiter assay, the PPC was found to have a concentration-dependent anti-biofilm activity (up to 85.15 ± 1.60%). Additionally, the fermentative conversion of the hydrolyzed bean straw by (KM504287.1) amounted to 65.80 ± 0.52% of the theoretical ethanol yield. Overall, for the first time, the present work reports the production of extremozymatic (thermo, alkali-, and halo-stable) cellulase from NBRM9. Therefore, this strain is recommended for use as a biotool in many lignocellulosic-based applications operating under harsh conditions.
放线菌是木质纤维素降解酶的一个有吸引力的来源。利用廉价的木质纤维素废料寻找产极端酶纤维素酶的放线菌仍然是酶研究的一个优先目标。在这种情况下，嗜极端放线菌NBRM9在固体和液体试验中显示出有前景的纤维素分解活性。基于其表型特征以及16S rRNA基因测序（OQ380604.1）的系统发育分析，该放线菌被鉴定为 。以豆秸作为最佳农业废料，使用响应面法对该菌株的纤维素酶生产进行了统计学优化，在培养温度40°C、pH值9、培养时间7天和底物浓度2%的条件下达到了最大活性（13.20 U/mL）。部分纯化的纤维素酶（PPC）在很宽的温度范围（20-90°C）、pH值范围（3-11）和NaCl浓度范围（1-19%）内显示出有前景的活性和稳定性，在50°C、pH 9.0和盐度10%时具有最佳活性。在这些条件下，该酶保留了>95%的活性，从而表明其极端酶的性质。纤维素酶的动力学表明其V为20.19±1.88 U/mL，Km为0.25±0.07 mM。固定化的PPC具有69.58±0.13%的相对活性。在体外微量滴定试验中，发现PPC具有浓度依赖性的抗生物膜活性（高达85.15±1.60%）。此外， （KM504287.1）对水解豆秸的发酵转化率达到了理论乙醇产量的65.80±0.52%。总体而言，本研究首次报道了从NBRM9生产极端酶（热稳定、碱稳定和卤稳定）纤维素酶。因此，推荐该菌株用作在苛刻条件下运行的许多基于木质纤维素的应用中的生物工具。
