Microbial Oxidation of Medium Chain Fatty Alcohol in the Synthesis of Sophorolipids by Candida bombicola and its Physicochemical Characterization

Sophorolipids (SL) are glycolipid biosurfactants abundantly produced from different feedstocks by yeasts and have been widely developed for various applications. The amphipathic structures of sophorolipids imparts to them surfactant type properties. These biosurfactants are readily isolated in high yield and are nontoxic and biodegradable, which make them industrially interesting as surfactants or emulsifiers. Sophorolipid production was carried out using glucose as a hydrophilic source and lauryl alcohol C_12–14, as a hydrophobic source by Candida bombicola (ATCC 22214). Process economics and environmental attractiveness was increased by using a low cost substrate. Optimization studies were carried out where the effect of glucose concentration, pH, temperature and metal ions on sophorolipid production was studied. Optimum production of sophorolipid obtained using lauryl alcohol (SLLA) was achieved after 96 h, the initial pH of the medium was 6.0 with 10 % glucose at 30 °C. Primary characterization of SLLA was done by FTIR. The SLLA showed high physicochemical properties in terms of the surface activities when compared with synthetic surfactants including dodecyl tetraethylene glycol ether and sodium lauryl sulfate. The surface tension of SLLA thus obtained was found to be 24 mN/m with a critical micellar concentration (CMC) value of 0.68 mg/L. Antimicrobial testing showed that SLLA have potent antimicrobial activity against both gram negative bacteria, Escherichia coli (ATCC 8739) and gram positive cocci, Staphylococcus aureuss (ATCC 2079).     

Low-Temperature Crystallization for Separating Monoacetylated Long-Chain Sophorolipids: Characterization of Their Surface-Active and Antimicrobial Properties

Pseudohyphozyma (formerly Rhodotorula) bogoriensis synthesizes long-chain-length (22-carbon chain) sophorolipids (22:0-SL) that are variously acetylated at the 6′- or/and 6″-carbons of the sophorose unit. In this paper, we describe a low-temperature crystallization protocol that preferentially separates the 6′-monoacetylated 22:0-SL (6′-Ac₁-22:0-SL) from a parental mixture of 22:0-SL containing a majority (64.7%) of the 6′,6″-diacetylated moiety (6′,6″-Ac₂-22:0-SL), as deduced from high-pressure-liquid-chromatography evaporative-light-scattering-detection (HPLC-ELSD) and LC/Q-TOF-MS analyses. Tensiometry measurements using the Wilhelmy plate method yielded minimum-surface-tension (SFT_min) and critical-micelle-concentration (CMC) values of 34.6 ± 1.0 mN m⁻¹ and 0.014 mM, respectively, for 6′-Ac₁-22:0-SL (CRYSTAL) fraction and 34.9 ± 1.0 mM m⁻¹ (SFT_min) and 0.018 (CMC) for the hexane precipitate (Hx-PRCP) fraction containing a high concentration (89.2%) of the diacetylated 6′,6″-Ac₂-22:0-SL after crystal removal. In contrast, the SFT_min and CMC of the well-studied 16-18 carbon (C_16-18)-SL of Starmerella bombicola were 35–37.2 mN m⁻¹ and 0.05-(>0.3) mM, respectively. Individually, the purified CRYSTAL and Hx-PRCP fractions exhibited a similar degree of strong growth-inhibition activity against Cutibacterium (formerly Propionibacterium) acnes as determined by an agar-plate zone of inhibition assay. Study on the growth inhibition of oral health-related bacteria, i.e., Streptococcus mutans and Lactobacillus acidophilus, showed that, depending on the bacteria and strains tested, the CRYSTAL fraction was either slightly better than or equally effective as the Hx-PRCP fraction in inhibiting cell growth.     

On the use of waste frying oil in the synthesis of sophorolipids

Sophorolipids are surface‐active agents which are synthesised by the yeast Candida bombicola. Here we present the possibility of reducing the economical and ecological cost of producing sophorolipids by using waste frying oil as a substrate for C. bombicola. A comparison is made between two grades of biodiesel, waste frying oil and the methyl ester of coco/palm oil as lipophilic substrates on a shakeflask level. Cultivations in a bioreactor using waste frying oil as a substrate were carried out. A new strategy for product recovery without the use of organic solvent is also proposed. The work presented here investigates whether it is possible to produce sophorolipids on waste frying oil and recover the product without using organic solvents.     

月桂醇环氧化加成及加成物性能研究

以月桂醇为原料加成环氧丙烷、环氧乙烷制备非离子表面活性剂，探讨了加成物的表面物性与环氧乙烷、环氧丙烷加成效的关系。实验证明：当环氧丙烷加成效为8—10mol，环氧乙烷加成效为20～25mol时，加成物的表面物性最佳。     

应用煎炸废油发酵制备槐糖脂生物表面活性剂

应用正交实验,优化了假丝酵母菌O-13-1以煎炸废油为油溶性碳源发酵槐糖脂的条件,并应用高效液相色谱-高分辨串联质谱（HPLC-MS/MS）鉴定了所产槐糖脂同系物的组成及结构。结果表明,经正交实验优化的O-13-1菌株以煎炸废油为底物制备槐糖脂的摇瓶发酵条件为：摇床转速200r/min,双碳源添加量均为90g/L,温度为25℃,接种量为体积分数12%,槐糖脂产量在菌株稳定生长期的后期即204h时达到最大,为57.64g/L;O-13-1菌株以煎炸废油为底物所合成槐糖脂由9种乙酰基取代的内酯型和酸型槐糖脂同系物构成,内酯型槐糖脂同系物所占质量分数达76%。基于摇瓶得到的以煎炸废油为油溶性碳源的优化发酵条件,O-13-1菌株在5L自动发酵罐中转速500r/min时发酵合成槐糖脂产量可达163.28g/L。以煎炸废油为碳源发酵槐糖脂的原料成本较普通大豆油降低18%,在有效降低槐糖脂生产成本的同时,实现了煎炸废油的资源化利用。     

应用煎炸废油发酵制备槐糖脂生物表面活性剂

应用正交实验,优化了假丝酵母菌O-13-1以煎炸废油为油溶性碳源发酵制备槐糖脂的条件,并应用高效液相色谱-高分辨串联质谱(HPLC-MS/MS)鉴定了所产槐糖脂同系物的组成及结构。结果表明,经正交实验优化的O-13-1菌株以煎炸废油为底物制备槐糖脂的摇瓶发酵条件为:摇床转速200 r/min,双碳源质量浓度均为90 g/L,温度为25℃,接种量为体积分数12%。在此条件下,槐糖脂产量达到最大,为73.26 g/L;O-13-1菌株以煎炸废油为底物所合成槐糖脂由9种乙酰基取代的内酯型和酸型槐糖脂同系物构成,内酯型槐糖脂同系物所占质量分数达76%。基于摇瓶得到的以煎炸废油为油溶性碳源的优化发酵条件,O-13-1菌株在5 L自动发酵罐中转速500 r/min时发酵合成槐糖脂产量可达163.28 g/L。以煎炸废油为碳源发酵槐糖脂的原料成本较普通大豆油降低18%,在有效降低槐糖脂生产成本的同时,实现了煎炸废油的资源化利用。     

固体超强酸催化合成谷氨酸月桂醇酯表面活性剂

以谷氨酸和月桂醇为原料,用固体超强酸ZrO2-SO∧2-4为催化剂合成谷氨酸月桂醇酯表面活性剂,探讨了反应温度、反应时间、物料配比和催化剂用量对合成反应的影响,结果表明该类催化剂催化效果良好,月桂醇转化率高,可达96%以上。     

环保型增塑剂松香十二醇酯的合成与表征

以松香、十二醇为原料,在无溶剂和氮气保护下,通过酯化反应合成了环保型增塑剂松香十二醇酯。在催化剂的筛选及最佳反应温度确定的基础上,通过L9(34)正交实验详细研究了松香十二醇酯的合成工艺,确定了最佳反应条件,即松香中树脂酸与十二醇的物质的量之比为1∶2.5,催化剂浓H2SO4用量为松香质量的5%,反应温度控制在140~145℃,反应时间为8 h。由此合成的产物产率为75.1%。然后通过傅立叶变换红外光谱、紫外-可见光谱、核磁共振氢谱、热重分析等手段对产物进行了表征和测试。结果表明,合成的产物即为目标产物松香十二醇酯,而其主分解温度为295℃,可以作为具有一定耐温性能的环保型增塑剂来使用。     

Surface-Active Properties and Antimicrobial Study of Conventional Cationic and Synthesized Symmetrical Gemini Surfactants

Symmetrical gemini surfactants of cationic series α,ω-alkanediyl bis (dimethyl ammonium bromide) commonly referred as “m–s–m” have been synthesized. Spectral analysis was performed to confirm compound structures and purity. Conductivity and surface tension measurements provide better understanding of the micellization process. Their self-assembly behavior in aqueous solution is also discussed in detail. The antimicrobial efficacy was measured by bacterial and fungal growth inhibition expressed as minimal inhibitory concentration values against five strains of a representative group of microorganisms viz. Bacillus subtilis, Staphylococcus aureus, Klebsiella pneumonia, Salmonella paratyphi B and Aspergillus niger. All of the synthesized surfactants showed antimicrobial activity against them, but at different levels depending on their structures. The surfactants possessing longer alkyl chains (more hydrophobic environment) demonstrated better antimicrobial functionality. The antimicrobial potency was found to be dependent on the representative target microorganism (Gram-positive bacteria > fungi > Gram-negative bacteria), as well as on the ionic nature of the surfactant (cationic), alkyl chain length (m = 12, 16) and spacer length (s = 2, 4, 6) of the synthesized compounds. Gemini surfactants such as 12-2-12 and 12-4-12 were found to be weakly active whereas 16-2-16 and 16-4-16 compounds proved to be the most potent antimicrobial surface-active agents among the synthesized gemini homologues.     

Jatropha oil and karanja oil as carbon sources for production of sophorolipids

Biosurfactants like sophorolipids (SL) are mild and environmentally friendly surfactants to be used in cosmetics and health care products. In addition to surfactant properties, SL also possess antimicrobial and skin healing properties. SL are produced by microbial fermentation using refined vegetable oils with glucose as a carbon source. This affects the economics of the production of SL. In the present work, non‐traditional oils like jatropha oil, karanja oil, and neem oil were used as newer feedstock for fermentative production of SL using Starmerella bombicola (ATCC 22214). In the fermentation, jatropha oil and karanja oil gave 6.0 and 7.6 g/L of SL (mainly lactonic form), respectively. HPLC, liquid chromatography–mass spectrometer, and ¹H NMR of crude SL obtained from fermentation broth showed lactonic form of two major SL. Oleic acid and linoleic acid were preferentially consumed over other fatty acids by the organism. Neem oil gave lower yield, i.e., 2.63 g/L of SL (mainly acidic form). Practical applications: Jatropha oil and karanja oil are one of the non‐traditional oils grown wildly in India that have large potential that is still to be explored. These oils contain non‐glycerides components that exclude their use as edible oil. These oils can be used as substrate for SL that can find novel applications like in soil remediation, skin care production, antimicrobial agents, low foaming detergents, and food additives. The current study has provided proof of concept work that has indicated the potential of these oils to be used as substrate for SL. It has opened new avenues and there is further scope to improve the yield by validating the process parameters like aeration rate, residual substrate recycle and pH control.     

In vitro Antimicrobial Activity of Ozonized Theobroma Oil Against Candida albicans

In this paper, a study of antimicrobial activity of ozonized theobroma oil against Candida albicans was carried out. Minimum inhibitory concentration and minimum fungicide concentration from ozonized theobroma oil for several peroxides indexes were determined. Mortality kinetics for peroxide index of 1200 mmol-eq/kg was carried out. Effect of contact time, peroxide index and ozonized theobroma oil concentration on Candida albicans mortality was studied. Under the conditions studied, minimum inhibitory concentration and minimum fungicide concentration values between 5 and 3.75 mg/mL and 11.58 and 5.78 mg/mL were obtained for peroxides indexes of 1002 and 1200 mmol-eq/kg of sample, respectively.

Microorganism inactivation follows first order kinetics. An optimal concentration value of 93.75 mg/mL was obtained. Further increases of ozonized theobroma oil concentration did not exert any influence on mortality. Under the variables ranges studied all parameters have a significant effect on the mortality of Candida albicans, contact time being the most important factor.     

系列醇醚羧酸盐的合成及性能研究

介绍了系列脂肪醇聚氧乙烯醚羧酸盐的合成和性能。通过正交试验确定了较佳的合成工艺条件 :投料摩尔比为n(AEO9)∶n(ClCH2 COOH)∶n(NaOH) =1∶2∶4 5 ,反应温度为 5 5℃ ,反应时间为 4 5h。并对系列醇醚羧酸盐进行物性测试 ,结果表明 :润湿性能均较好 ,临界表面张力随加成数的增加而增大 ,泡高随加成数的增加而减少     

聚乙烯醇脱氢酶的分离纯化及其酶学性质

采用(NH4)2SO4分级沉淀及Q-Sepharose HP柱层析两步纯化,首次从可高效降解聚乙烯醇(PVA)的混合菌系发酵产物中分离纯化获得了纯蛋白聚乙烯醇脱氢酶(PVADH),并对其酶学性质进行了研究. 结果表明,PVADH分子量为134.3 kDa,最适作用温度为35℃,最适作用pH值为7.5;PVADH以仲醇为底物时酶活性普遍高于以其他醇类为底物时,PVADH与PVA反应产物中检测到羰基化合物,证实PVADH对PVA有降解作用.     

利用环己烷/乙醇废液制备凝胶燃料

采用固体酒精的三种典型制备方法,尝试将相图实验的环己烷/乙醇混合废液制成类似固体酒精的凝胶燃料,实验结果表明:(1)醋酸钙法不适用;(2)硬脂酸-氢氧化钠法可用;(3)溶胶-凝胶法中使用羟丙基甲基纤维素(HPMC)较合适;(4)在硬脂酸-氢氧化钠法中加入HPMC(羟丙基甲基纤维素)得到的凝胶燃料性能最好;(5)与固体酒精相比,环己烷/乙醇凝胶燃料优点是火大、耐烧、热值高,缺点是久燃锅底易黑,久放罐中味重。提出了使用消烟剂、加厚工业酒精凝胶包覆层等改进设想。     

聚乙烯醇/改性纳米蒙脱土复合材料的制备与性能

纳米蒙脱土(MMT)用十六烷基三甲基溴化铵进行改性制得有机改性的MMT(OMMT),用其作为聚乙烯醇(PVAL)的改性材料,采用溶液共混、流涎成膜制得PLA/OMMT复合材料,考察了OMMT的用量对PVAL复合材料性能的影响。用傅立叶变换红外光谱(FTIR)仪、差示扫描量热仪、扫描电子显微镜、X射线衍射仪、万能力学试验机等对复合材料性能及结构进行表征和分析。结果表明,FTIR显示十六烷基三甲基溴化铵成功进入MMT结构中,OMMT成功制得;随着OMMT添加量的增加,复合材料热稳定性提高,断裂伸长率降低,拉伸强度呈现先增加后降低趋势,当其含量为9%时达到最大;SEM显示OMMT含量9%时,OMMT与PVAL相容性最好,表面光滑,含量再增加,出现团聚现象,力学性能受到影响。     

十二烷基聚氧乙烯基(5)氧化胺的合成及其性能

以十二胺聚氧乙烯(5)醚(AC-1205)和质量分数30%的双氧水为原料,合成了十二烷基聚氧乙烯基(5)氧化胺表面活性剂,通过质谱和红外光谱对其结构进行表征。并测定其表面活性、乳化性能、抗硬水性能。结果表明,该表面活性剂具有良好的表面活性,其临界胶束浓度(CMC)为8.13×10~(-4)mol/L,最小表面张力γCMC为35.6mN/m,还具有良好的乳化性和抗硬水性,其分水时间为668 s,在硬水中的平均稳定性和差示稳定性分别为5级和555,优于原料AC-1205。     

丁辛醇的生产技术进展和消费现状分析

阐述了丁辛醇国内外生产技术进展情况,重点介绍了丙烯羰基化合成丁辛醇催化剂的研究进展情况,指出研究开发单程不循环工艺以及开发新型高效配位体改性铑催化剂是发展方向。文章对我国丁辛醇的生产状况和消费现状进行了分析。