Costa Andrea F S, Almeida Fabíola C G, Vinhas Glória M, Sarubbo Leonie A
Northeast Biotechnology Network, Federal Rural University of Pernambuco, Recife, Brazil.
Design and Communication Center, Academic Region Agreste Center, Federal University of Pernambuco, Caruaru, Brazil.
Front Microbiol. 2017 Oct 17;8:2027. doi: 10.3389/fmicb.2017.02027. eCollection 2017.
Cellulose is mainly produced by plants, although many bacteria, especially those belonging to the genus , produce a very peculiar form of cellulose with mechanical and structural properties that can be exploited in numerous applications. However, the production cost of bacterial cellulose (BC) is very high to the use of expensive culture media, poor yields, downstream processing, and operating costs. Thus, the purpose of this work was to evaluate the use of industrial residues as nutrients for the production of BC by UCP1619. BC pellicles were synthesized using the Hestrin-Schramm (HS) medium and alternative media formulated with different carbon (sugarcane molasses and acetylated glucose) and nitrogen sources [yeast extract, peptone, and corn steep liquor (CSL)]. A jeans laundry was also tested. None of the tested sources (beside CSL) worked as carbon and nutrient substitute. The alternative medium formulated with 1.5% glucose and 2.5% CSL led to the highest yield in terms of dry and hydrated mass. The BC mass produced in the alternative culture medium corresponded to 73% of that achieved with the HS culture medium. The BC pellicles demonstrated a high concentration of microfibrils and nanofibrils forming a homogenous, compact, and three-dimensional structure. The biopolymer produced in the alternative medium had greater thermal stability, as degradation began at 240°C, while degradation of the biopolymer produced in the HS medium began at 195°C. Both biopolymers exhibited high crystallinity. The mechanical tensile test revealed the maximum breaking strength and the elongation of the break of hydrated and dry pellicles. The dry BC film supported up to 48 MPa of the breaking strength and exhibited greater than 96.98% stiffness in comparison with the hydrated film. The dry film supported up to 48 MPa of the breaking strength and exhibited greater than 96.98% stiffness in comparison with the hydrated film. The values obtained for the Young's modulus in the mechanical tests in the hydrated samples indicated low values for the variable rigidity. The presence of water in the interior and between the nanofibers of the hydrated BC only favored the results for the elasticity, which was 56.37% higher when compared to the dry biomaterial.
纤维素主要由植物产生，不过许多细菌，尤其是属于 属的细菌，能产生一种非常特殊形式的纤维素，其机械和结构特性可用于众多应用。然而，由于使用昂贵的培养基、产量低、下游加工以及运营成本等原因，细菌纤维素（BC）的生产成本非常高。因此，本研究的目的是评估利用工业废渣作为营养物质，供UCP1619生产BC。使用赫斯特林 - 施拉姆（HS）培养基以及用不同碳源（甘蔗 molasses 和乙酰化葡萄糖）和氮源[酵母提取物、蛋白胨和玉米浆（CSL）]配制的替代培养基合成BC薄膜。还测试了牛仔布洗涤废水。除了CSL之外，所测试的其他来源均不能作为碳源和营养替代品。用1.5%葡萄糖和2.5% CSL配制的替代培养基在干质量和湿质量方面产量最高。在替代培养基中产生的BC质量相当于用HS培养基所获得质量的73%。BC薄膜显示出高浓度的微纤维和纳米纤维形成均匀、致密的三维结构。在替代培养基中产生的生物聚合物具有更高的热稳定性，因为降解始于240°C，而在HS培养基中产生的生物聚合物降解始于195°C。两种生物聚合物都表现出高结晶度。机械拉伸试验揭示了湿态和干态薄膜的最大断裂强度和断裂伸长率。与湿态薄膜相比，干BC薄膜支撑高达48 MPa的断裂强度，并且表现出大于96.98%的刚度。在湿态样品的机械测试中获得的杨氏模量值表明可变刚度的值较低。湿态BC的纳米纤维内部和之间存在的水仅有利于弹性结果，与干生物材料相比，弹性提高了56.37%。
