Characterisation and development of bacterial biosurfactants for biotechnological applications.

用于生物技术应用的细菌生物表面活性剂的表征和开发。

• 批准号: 2271567
• 金额: --
• 依托单位: Heriot-Watt University
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2271567
• 关键词: Characterisation; development; bacterial; biosurfactants; biotechnological; Characterisation; development; bacterial; biosurfactants; biotechnological

Specific objectives of the project:1. To first select a subset of bacterial strains that produce powerful surface-active agents (i.e. bioemulsifiers or biosurfactants).2. Determine the growth kinetics and production of the SAs during growth of the strains in pre-optimised liquid medium.3. To recover and partially purify small-scale quantities of the SAs and determine their composition by, for e.g., chemical assays, NMR etc.4. To determine the functional properties of the SAs, such as their pH and temperature tolerances, interaction with different oil substrates, critical micelle concentration etc.5. To optimise the production of the SAs by the strains using initially flask-based cultures followed by small-scale fermenter studies.6. To explore protocols and fine-tune the experimental conditions of the SAs for subsequent testing to evaluate their potential for use in commercial formulations and/or biotechnological applications.Methodology:To screen for strains that produce SAs with emulsifying properties (i.e. bio-emulsifiers), sugar substrates (e.g. glucose, sucrose, malt extract) will be tested since these have been shown, from our experience, to be suitable feedstocks for yielding powerful bio-emulsifiers from marine bacterial strains. A standard emulsification assay, which involves emulsifying the spent culture medium against an oil substrate, will be used to identify strains that produce bio-emulsifiers that form oil-in-water (O/W) and/or water-in-oil (W/O) emulsions. High O/W and W/O emulsification activities, of at least 50% relative to uninoculated controls, will be used as the criterion for the selection of strains for further evaluation.For strains that produce SAs with surfactant properties (i.e. bio-surfactants), oil substrates (e.g. rapeseed oil) will be used because they are recognized to favour the production of SAs with surfactant, rather than emulsifying, properties. During incubation of the strains on different oil substrates, the interfacial meniscus, which sits at the boundary between the lower aqueous and upper non-aqueous (oil) phases, will be monitored for any change to its curvature. Strains that completely straighten the interfacial meniscus - a positive indication of bio-surfactant production - will be selected for further evaluation using surface and interfacial measurements in the production medium.Strains selected for producing SAs with putative powerful surface-active properties will be regrown under the same conditions that yielded these activities, this time to determine if the SAs are cell-bound or released extracellularly into the culture medium. This is important because the physical location (cell-bound or extracellularly released) of the SA molecules in the culture medium during their production, such as in a fermentation process, can have a significant impact to the processes involved in their recovery and, in turn, whether it is economically feasible. To determine this, the cells will be removed from the culture medium and thoroughly washed prior to testing if they possess emulsifying and/or surfactant activities. The same will be tested on the cell-free spent medium. Only strains that are found to produce extracellulary-released SAs exhibiting high emulsifying and/or surfactant qualities will be selected for further study.Properties of the SAs will be determined for various conditions (i.e. tolerances to temperature, pH, salinity, etc.) and the oil substrates they are able to emulsify and/or reduce their surface tension will also be determined. Criteria that will be used for selecting candidate SAs for further development will be based on their ability to confer high stabilization and emulsification activities and/or surface tension reduction. This PhD project aims to discover new types of SAs produced by novel marine bacterial strains, and provide new knowledge on the properties of the SAs the strains produce, including their potential biotechnological use.

项目的具体目标：1。首先选择产生强大表面活性剂（即生物乳化剂或生物表面活性剂）的细菌菌株的子集。2。在预优化的液体培养基中，确定菌株生长过程中SA的生长动力学和生产。3。为了恢复并部分净化少量SAS，并通过化学分析，NMR等确定其组成。4。为了确定SA的功能特性，例如它们的pH和温度公差，与不同的油基板的相互作用，临界胶束浓度等。5。使用最初基于烧瓶的培养物，然后进行小规模发酵罐研究，通过菌株优化SAS的生产。6。探索协议并微调SA的实验条件，以评估其在商业配方和/或生物技术应用中的潜力。方法论：筛选产生具有乳化性能（即生物乳液）的SA的菌株（即生物 - 乳液）的菌株（例如，糖的糖）（例如，糖）的经验（例如，Malt）是对这些的经验，因为我们的经验是对这些菌株的经验，因为这些菌株是对这些菌株的测试。用于从海洋细菌菌株中产生强大生物乳剂的原料。标准的乳化测定法涉及对石油底物进行乳化培养基的乳化培养基，以识别产生形成水中油（O/W）和/或油中油（W/O）乳液的生物乳化剂的菌株。高O/W和W/O乳化活性，相对于未接种对照至少50％，将用作选择菌株进行进一步评估的标准。对于具有表面活性剂特性（即生物表面活性剂）产生SAS的菌株（即生物表面活性剂），将使用油基材料（例如，采用油性油）与SAS相比，将其识别为SAS的生产。在不同的油基质上孵育菌株期间，将监视下层水性和非水（油）阶段之间边界的界面半月板，以确保其曲率的任何变化。将在生产培养基中的表面和界面测量中选择完全拉直界面半月板的菌株 - 生物表面活性剂生产的积极指示。在生产具有强大的表面活性的SAS中，将在这些活动中恢复具有相同的条件，以确定SAS是否会产生SAS或释放的培养基。这很重要，因为在生产过程中，培养基中SA分子的物理位置（细胞结合或细胞外释放），例如在发酵过程中，可以对恢复的过程产生重大影响，而这反过来又在经济上是可行的。为了确定这一点，如果细胞具有乳化和/或表面活性剂活性，则将从培养基中清除并在测试前进行彻底洗涤。将在无单元的花费介质上测试相同的测试。只有被发现会产生表现出高度乳化和/或表面活性剂品质的细胞外释放的SA的菌株才能选择进一步研究。SAS的特性将在各种条件下确定（即，对温度，pH，盐分，盐度等的耐受性），以及他们能够确定乳化和/或减少表面张力的油基材料。将用于选择候选SA的标准将基于其赋予高稳定和乳化活动和/或表面张力减少的能力。该博士学位项目旨在发现新型海洋细菌菌株产生的新型SA，并提供有关菌株产生的SAS特性的新知识，包括其潜在的生物技术使用。