雌激素和Candidalysin在外阴阴道念珠菌病中的研究进展

外阴阴道念珠菌病(VVC)主要由白念珠菌(CA)引起。增加外周血雌激素水平如怀孕、口服避孕药的使用和激素替代疗法等增加VVC易感性。雌激素可通过调控CA菌丝生长、宿主固有免疫细胞和阴道上皮细胞的免疫功能等多种方式影响VVC进展,但具体机制仍不清楚。Candidalysin(CL)是一种对黏膜感染至关重要的真菌肽毒素,在CA感染中起着重要作用。CL由ECE1基因编码,雌激素调控ECE1表达。本文就雌激素和CL与VVC之间相关性进行综述,为进一步明确雌激素和CL在VVC发病机制中的作用提供参考。

Epidemiology, Clinical Features and Antifungal Resistance Profile of Candida auris in Africa: Systematic Review

Candida auris since it discovery in 2009 is becoming a severe threat to human health due to its very quickly spread, its worldwide high resistance to systemic antifungal drugs. In resource-constrained settings where several conditions are met for its emergence and spread, this worrisome fungus could cause large hospital and/or community-based outbreaks. This review aimed to summarize the available data on C. auris in Africa focusing on its epidemiology and antifungal resistance profile. Major databases were searched for articles on the epidemiology and antifungal resistance profile of C. auris in Africa. Out of 2,521 articles identified 22 met the inclusion criteria. In Africa, nearly 89% of African countries have no published data on C. auris. The prevalence of C. auris in Africa was 8.74%. The case fatality rate of C. auris infection in Africa was 39.46%. The main C. auris risk factors reported in Africa were cardiovascular disease, renal failure, diabetes, HIV, recent intake of antimicrobial drugs, ICU admissions, surgery, hemodialysis, parenteral nutrition and indwelling devices. Four phylogenetic clades were reported in Africa, namely clades I, II, III and IV. Candida auris showed a pan-African very high resistance rate to fluconazole, moderate resistance to amphotericin B, and high susceptibility to echinocandins. Finally, C. auris clade-specific mutations were observed within the ERG2, ERG3, ERG9, ERG11, FKS1, TAC1b and MRR1 genes in Africa. This systematic review showed the presence of C. auris in the African continent and a worrying unavailability of data on this resilient fungus in most African countries.

Ability of Helicobacter pylori to internalize into Candida

The following are our views regarding the“letter to the editor”(Helicobacter is preserved in yeast vacuoles!Does Koch’s postulates confirm it?)by Alipour and Gaeini,and the response“letter to the editor”(Candida accommodates nonculturable Helicobacter pylori in its vacuole-Koch’s postulates aren’t applicable)by Siavoshi and Saniee.Alipour and Gaeini rejected the methods,results,discussion,and conclusions summarized in a review article by Siavoshi and Saniee.The present article reviews and discusses evidence on the evolutionary adaptation of Helicobacter pylori(H.pylori)to thrive in Candida cell vacuoles and concludes that Candida could act as a Trojan horse,transporting potentially infectious H.pylori into the stomach of humans.

Antimicrobial and synergistic effects of lemongrass and geranium essential oils against Streptococcus mutans,Staphylococcus aureus,and Candida spp.

BACKGROUND The oral cavity harbors more than 700 species of bacteria,which play crucial roles in the development of various oral diseases including caries,endodontic infection,periodontal infection,and diverse oral diseases.AIM To investigate the antimicrobial action of Cymbopogon Schoenanthus and Pelargonium graveolens essential oils against Streptococcus mutans,Staphylococcus aureus,Candida albicans,Ca.dubliniensis,and Ca.krusei.METHODS Minimum microbicidal concentration was determined following Clinical and Laboratory Standards Institute documents.The synergistic antimicrobial activity was evaluated using the Broth microdilution checkerboard method,and the antibiofilm activity was evaluated with the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide assay.Data were analyzed by one-way analysis of variance followed by the Tukey post-hoc test(P≤0.05).RESULTS C.schoenanthus and P.graveolens essential oils were as effective as 0.12%chlorhexidine against S.mutans and St.aureus monotypic biofilms after 24 h.After 24 h P.graveolens essential oil at 0.25%was more effective than the nystatin group,and C.schoenanthus essential oil at 0.25%was as effective as the nystatin group.CONCLUSION C.schoenanthus and P.graveolens essential oils are effective against S.mutans,St.aureus,Ca.albicans,Ca.dubliniensis,and Ca.krusei at different concentrations after 5 min and 24 h.

基于代谢组学和转录组学揭示郫县豆瓣中两株优势产风味菌株Bacillus amyloliquefaciens与Candida versatilis互作机制

为揭示郫县豆瓣内源性优势菌株Bacillus amyloliquefaciens与Candida versatilis的互作机制,文章基于非靶向代谢组学和转录组学技术,探究了两株菌在单独培养和共培养体系下代谢物和基因表达水平的差异。结果表明,与单独培养B.amyloliquefaciens与C.versatilis相比,共培养体系下分别有193种和297种显著差异代谢物,集中在脂类和类脂分子、有机酸及其衍生物、氨基酸及其衍生物等。通过转录组学和差异代谢通路分析,B.amyloliquefaciens在共培养体系下上调表达基因801个,集中在生物过程中;而下调表达基因805个,以分子功能为主。C.versatilis对B.amyloliquefaciens的生长代谢具有双向作用,其中糖酵解/糖异生、脂肪酸降解等途径显著增强,而脂肪酸合成、氨基酸相关代谢显著减弱。研究结果可揭示两株菌的互作机制,并为改善郫县豆瓣风味及品质提供理论指导。

Candida endocarditis: Update on management considerations

The rise in incidence rates of invasive candidiasis warrants an increase in atten-tion and efforts toward preventing and treating this virulent infection.Cardiac involvement is one of the most feared sequelae and has a poor prognosis.Despite the introduction of several novel antifungal agents over the past quarter century,complications and mortality rates due to Candida endocarditis have remained high.Although fungal endocarditis has a mechanism similar to bacterial endocar-ditis,no specific diagnostic criteria or algorithm exists to help guide its manage-ment.Furthermore,recent data has questioned the current guidelines recommen-ding a combined approach of antifungal agents with surgical valve or indwelling prostheses removal.With the emergence of multidrug-resistant Candida auris,a focus on improved prophylactic measures and management strategies is nece-ssary.

One Step Multiplex PCR for Identification of Candida haemulonii complex and Candia auris

Purpose: Recently, Candida haemulonii complex (Candida haemulonii, Candida duobushaemulonii and Candida haemulonii var. vulnera) and two genetically close species (Candida pseudohaemulonii and Candida auris) have emerged as an opportunistic fungal pathogen associated with various infectious diseases of humans, and most of those isolates have displayed antifungal resistance. Because it is difficult to differentiate these microorganisms by a current technique, unfortunately, it is important to establish a method for identifying them accurately. The purpose of the present study was to design species-specific primers in order to identify and detect C. auris, C. pseudohaemulonii, and C. haemulonii complex, i.e. , C. haemulonii, C. duobushaemulonii and C. haemulonii var. vulnera using a multiplex PCR. Methods: Polymerase chain reaction (PCR) primers were designed based on partial sequences of the 26S rRNA, 18S rRNA, and RPB1 genes and ITS region of five Candida species. Results: The multiplex PCR method developed in this study was able to distinguish five Candida species clearly. Conclusion: Our developed one-step multiplex PCR method is accurate, specific, cost-effective, time-saving, and works without requiring DNA extraction.

Anticandidal Activity of Moroccan Medicinal Plants

The prevalence of oral candidiasis has increased over recent years in patients with the compromised general condition. There are a large number of plant species that have been traditionally used for oral diseases by the Moroccan population. These species could provide a source for discovering new active principles of natural origin against Candida albicans involved in the appearance of candidiasis infections. Information was acquired using the electronic databases Web of Science, Scopus and PubMed. In the first part, this review presents the medicinal plants used by the Moroccan population for the treatment of oral disorders (Toothaches, gingivitis, ulcers, stomatitis, abscesses, ...). The second part describes different studies regarding the antifungal activity of essential oils and organic extracts of some Moroccan species against Candida albicans. Inhibition zone diameter (IZD), Minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) values of essential oils and plant’s extracts were noted. The third part concerns Moroccan plants with the antifungal activity that can be used in medical and agricultural fields. Several species of Moroccan plant proved their effectiveness against Candida albicans and can be used for the treatment of oral candidiasis. Further research should be undertaken in the future to investigate the toxicity of essential oils and plant extracts with antifungal properties for clinical use. This review provided an update on Moroccan plants presenting antifungal activity and especially those active against Candida albicans.

Conjugation of Candida rugosa lipase with hydrophobic polymer improves esterification activity of vitamin E in nonaqueous solvent

We described a novel polymer-lipase conjugate for high-efficient esterification of vitamin E using vitamin E and succinic anhydride as the substrates in nonaqueous media.In this work,the monomer,N-isopropylacrylamide(NIPAM),was grafted onto Candida rugosa lipase(CRL)to synthesize poly(NIPAM)(pNIPAM)-CRL conjugate by atom transfer radical polymerization via the initiator coupled on the surface of CRL.The result showed that the catalytic efficiencies of pNIPAM-CRL conjugates(19.5-30.3 L·s^(-1)·mmol^(-1))were at least 7 times higher than that of free CRL(2.36 L·s^(-1)·mmol^(-1))in DMSO.It was attributed to a significant increase in Kcat of the conjugates in nonaqueous media.The synthesis catalyzed by pNIPAM-CRL co njugates was influenced by the length and density of the grafted polymer,water content,solvent polarity and molar ratio of the substrates.In the optimal synthesis,the reaction time was shortened at least 7 times,and yields of vitamin E succinate by pNIPAM-g-CRL and free CRL were obtained to be 75.4%and 6.6%at 55℃after the reaction for 1.5 h.The result argued that conjugation with pNIPAM induced conformational change of the lid on CRL based on hydrophobic interaction,thus providing a higher possibility of catalysis-favorable conformation on CRL in nonaqueous media.Moreover,pNIPAM conjugation improved the thermal stability of CRL greatly,and the stability improved further with an increase of chain length of pNIPAM.At the optimal reaction conditions(55℃and 1.5 h),pNIPAM-g-CRL also exhibited good reusability in the enzymatic synthesis of vitamin E succinate and kept~70%of its catalytic activity after ten consecutive cycles.The research demonstrated that pNIPAM-g-CRL was a more competitive biocatalyst in the enzymatic synthesis of vitamin E succinate and exhibited good application potential under harsh industrial conditions.

Candida glycerinogenes基因组大片段缺失菌的构建及表征

通过基因组精简可获得代谢背景降低、更适用于工业生物技术的底盘细胞。产甘油假丝酵母(Candida glycerinogenes)是具有优良抗逆性能的工业菌株,对其基因组进行精简以获得更优的底盘化细胞。以CRISPR/Cas9为工具进行C.glycerinogenes基因组非必需DNA大片段删除,实现了25、50 kb片段的敲除,并研究了缺失菌的耐受性和发酵特性。结果显示,片段删除菌株的胁迫耐受能力无明显改变,30℃下Δ7.8 kb菌生物量降低20%,42℃下Δ7.8 kb、Δ25 kb菌的生物量下降20%。而在发酵过程中各缺失菌均表现出生物量降低20%,其中Δ7.8 kb菌株表现出了发酵初生物量提高了14%、单位菌体甘油产量提高了22%,还原力相关基因G6PD、6PGDH分别上调10倍和29倍,NADPH/NADP+值提高了100%。结果表明,上述非必需DNA大片段删除对C.glycerinogenes耐受特性无明显影响,而会导致生物量降低和单位菌体甘油产量提高,缺失菌株可能因基因表达水平的差异而与野生菌株在性状上产生区别。该研究是对CRISPR/Cas9系统在C.glycerinogenes中的潜力挖掘,有助于推进该非模式工业菌株底盘化进程和应用。

Efficacy and safety of local candida immunotherapy in recalcitrant warts in pediatric kidney transplantation:A case report

BACKGROUND Warts are common in recipients of kidney transplantation(KT).Resistant warts which are not amenable to conventional therapies may lead to significant morbidity.Limited data exists on safety and efficacy of local immunotherapy among immunocompromised KT recipients.CASE SUMMARY We report a seven-year-old child who presented with recalcitrant plantar periungual warts in the early KT period.Immunosuppression consisted of tacrolimus,mycophenolate and steroid.Due to failure of conventional anti-wart therapies,he was treated with two sessions of intralesional(IL)candida immunotherapy along with liquid nitrogen cryotherapy leading to complete resolution of the warts.Interestingly,de novo BK viremia was seen about three weeks following the last candida immunotherapy.This required reduction of immunosuppression and other anti-BK viral therapies.Allograft function remained stable but there were donor specific antibodies detected.There also was elevated level of plasma donor derived cell-free DNA.A pneumocystis jirovecii pneumonia occurred ten months following completion of immunotherapy that was successfully treated with trimethoprim-sulfamethoxazole.During this ten-month follow-up period,there have been no recurrence of warts,and transplant kidney function has remained stable.CONCLUSION Stimulation of cell-mediated immunity against the human papilloma virus induced by the IL candida immunotherapy is thought to be a cause for wart resolution.With this therapy,whether it is necessary to augment the immunosuppression to prevent rejection is unclear as that may come with a risk of infectious complications.Larger,prospective studies in pediatric KT recipients are needed to explore these important issues.

白念珠菌气道定植对铜绿假单胞菌所致呼吸机相关性肺炎的影响

目的探讨白念珠菌气道定植对多重耐药铜绿假单胞菌所致呼吸机相关性肺炎(ventilator-associated pneumonia,VAP)患者病死率、抗菌药物疗程、免疫状态及炎症状态的影响。方法本前瞻性多中心队列研究以2018年6月至2023年6月收治于6所三级甲等综合教学医院重症医学科的多重耐药铜绿假单胞菌所致VAP患者为研究对象。根据患者呼吸道是否存在白念珠菌定植分为定植组及非定植组。比较两组患者30 d全因死亡率、抗菌药物敏感性及疗程、诊断VAP后第1、3、5、7天免疫指标及炎症指标变化。结果5年研究期间共纳入多重耐药铜绿假单胞菌导致VAP患者232例,其中白念珠菌定植组105例,非定植组127例。非定植组患者检出的铜绿假单胞菌对于氨基糖苷类、头孢菌素类及碳青霉烯类抗菌药物的敏感性均高于定植组(P<0.05),但两组患者对于16种抗菌药物的敏感性均低于中国细菌耐药监测网(China antimicrobial surveillance network,CHINET)2022年水平(P<0.05)。研究发现非定植组患者白介素-17A、(1,3)-β-D葡聚糖在各时间节点均低于定植组,且其他炎性指标更容易恢复至正常范围(P<0.05),同时非定植组患者的T及Th淋巴细胞绝对值可以在第7天更快地恢复至正常水平(P<0.05)。两组患者30 d全因死亡率差异无统计学意义(25.7%vs 22.8%,P=0.61),但非定植组抗菌药物的疗程明显短于定植组[(11.3±3.1)d vs(14.2±4.7)d,P<0.01],且存在重症医学科住院时间缩短的趋势。结论气道白念珠菌定植不影响多重耐药铜绿假单胞菌所致VAP患者的30 d全因死亡率,但会延长炎症反应及抗菌药物使用时间并导致免疫功能延迟恢复。

基于抑菌实验和网络药理学探讨D-柠檬烯、2-茨醇对白色念珠菌的抑制作用

目的:采用抑菌实验研究蛇床子-冰片药对成分中的D-柠檬烯及2-茨醇的体外抗白色念珠菌作用,并运用网络药理学预测D-柠檬烯和2-茨醇治疗念珠菌病的核心靶点和通路。方法:以白色念珠菌为研究对象,K-B纸片扩散法分别测定0.5、1.0、1.5 mg的D-柠檬烯、2-茨醇、制霉菌素的药液抑菌圈直径;采用试管双倍稀释法和棋盘法,测定D-柠檬烯、2-茨醇的最低抑菌浓度(MIC)以及两两联用的MIC,计算出联合抑菌分数(FIC)。通过Pubchem、SwissTargetPrediction数据库预测D-柠檬烯、2-茨醇的有效靶点;通过GeneCards、OMIM数据库检索念珠菌病相关的疾病靶点;运用Venny软件获得两种化学成分和念珠菌病的共同靶点;运用Cytoscape 3.9. 0软件构建“成分-靶点-疾病”网络;利用STRING数据库构建蛋白互作PPI网络;利用R软件进行GO功能及KEGG通路富集分析。结果:D-柠檬烯的MIC为5 mg/mL,2-茨醇的MIC为2.5 mg/mL。D-柠檬烯与2-茨醇联用的FIC指数为0.75,呈相加作用。网络药理学筛选得到两种成分相关作用靶点152个,疾病靶点893个,两者交集靶点为24个;网络拓扑分析得到核心靶点为肿瘤坏死因子(TNF)、过氧化物酶体增殖物激活受体γ(PPARG)、雌激素受体(ESR1)等;KEGG分析得到核心通路为C型凝集素受体信号通路(C-type lectin receptor signaling pathway)、Fc epsilon RI信号通路(Fc epsilon RI signaling pathway)、催乳素信号通路(prolactin signaling pathway)等。结论:D-柠檬烯、2-茨醇对白色念珠菌均有抑制作用,且2种组分药物联合使用具有一定的协同作用。网络药理学预测初步提示D-柠檬烯、2-茨醇可能通过作用于TNF、PPARG、ESR1等核心靶点调控C型凝集素受体信号通路(C-type lectin receptor signaling pathway)、Fc epsilon RI信号通路(Fc epsilon RI signaling pathway)等以治疗念珠菌病。

青藏高原肺结核合并念珠菌感染患者的病原菌分布特点及耐药率分析

目的研究青藏高原肺结核患者中机会性念珠菌病原学分布特点及耐药情况。方法分析2020年3月1日至2020年12月31日青海省第四人民医院3012例住院肺结核患者,收集痰标本,采用VITEK-32-YBC全自动细菌分析系统进行念珠菌鉴定,并对检出的念珠菌进行药敏试验。结果在本次调查的3012例肺结核患者中,合并念珠菌感染的肺结核患者有283例,占9.40%。其中,念珠菌类型又以白念珠菌为主,占总数的79.86%。结论青藏高原地区肺结核合并念珠菌感染的患病率较高。因此,选择抗菌药物要根据患者的情况综合分析,以此来选择最佳、最有效的药物治疗方法。

爱媛类芽孢杆菌抗菌肽对白色念珠菌生物膜的抑制作用机制

研究爱媛类芽孢杆菌抗菌肽对白色念珠菌生物膜的抑制作用,采用微量二倍稀释法和时间-杀菌曲线测定抑制效果,显微镜观察对白色念珠菌芽管和菌丝形成的影响,2,3-二(2-甲氧基-4-硝基-5-磺酸基苯基)-2H-四唑-5-甲酰苯胺法研究对生物膜、预成型生物膜形成和成熟生物膜清除率的影响,荧光探针观察对生物膜结构和膜内菌体状态的影响,平板涂布法和实时聚合酶链式反应测定生物膜内活菌数量和相关基因表达水平。结果表明,抗菌肽对白色念珠菌的最小抑菌浓度为8.28 AU/mL。抗菌肽能降低白色念珠菌的芽管形成率,阻止菌丝的生成,使其以酵母形式存在。抗菌肽对生物膜的形成和清除产生影响,能在较短时间内破坏生物膜的结构完整性,导致菌体受损和死亡,减少膜内菌落数量。在基因水平上,抗菌肽可降低多个生物膜形成相关的基因(如ALS1、ALS3、HWP1、EFG1、ECE1和UME6)的表达水平,从而抑制生物膜的形成。研究证明抗菌肽能够有效抑制白色念珠菌生物膜形成、成熟膜清除、成膜基因表达等,结果可为白色念珠菌新型抑菌物质的开发奠定理论基础,为食品病原微生物污染防治和食品质量安全保障提供依据。

老年念珠菌血流感染患者临床特征及预后影响因素分析

目的分析30 d不同预后老年念珠菌血流感染患者的临床特征及预后影响因素。方法收集2018年1月—2023年12月广州某三级甲等医院收治的58例≥65岁老年念珠菌血流感染患者资料,根据30 d预后情况分成存活组(34例)与死亡组(24例)分析其临床特点以及影响预后的因素。结果老年念珠菌血流感染患者死亡率41.4%(24/58例),两组感染菌株均以白念珠菌、光滑念珠菌、近平滑念珠菌、热带念珠菌为主,分离菌株对体外药敏试验耐药率低,两组的不同菌株占比、药物敏感性、感染部位差异无统计学意义。对两组预后单因素分析显示白细胞计数、C反应蛋白、降钙素原等炎症指标增高,血清蛋白降低,有呼吸系统基础疾病是患者死亡的危险因素(P<0.05);多因素回归分析提示血清蛋白降低是患者死亡的独立危险因素(OR=0.800,95%CI 0.676~0.946)。血培养报阳后48 h内未使用抗真菌治疗患者死亡率显著增高。结论老年患者因呼吸系统等基础疾病是念珠菌血流感染的高危人群,一旦感染预后差、死亡率高,及时纠正低蛋白血症,及时进行抗真菌治疗,对提高患者的预后有积极意义。

脊柱白念珠菌感染1例并文献复习

患者,男,32岁,因“检查发现双侧肋软骨及脊柱多发骨破坏4个月”入院。患者4个月前因回肠造瘘术后,拟行回肠还纳入住我院肿瘤外科,完善检查发现双侧肋软骨及脊柱多发骨破坏,行超声引导下肋软骨穿刺活检术,病理考虑慢性化脓性炎,未行治疗。入院1个月前复查骨破坏范围增大,再次行超声引导下肋软骨穿刺活检术,术后送结核分枝杆菌DNA检测,结果为阴性。此次因腰痛症状逐渐加重入院,体检腰、骶椎中线及椎旁压痛,腰椎屈伸活动受限,双下肢运动、感觉及反射正常。完善常规检查后行CT引导下腰椎穿刺活检及培养,明确诊断为白念珠菌感染。采用氟康唑静滴,3周后改为口服药物治疗,8周后复查腰痛症状明显改善,MRI示:椎体上下缘骨侵蚀及椎间盘破坏减轻。病情较前明显好转,随访中。

依维莫司单独与联合唑类药物对耐药念珠菌体外敏感研究

目的探讨依维莫司单独及联合伊曲康唑、伏立康唑、泊沙康唑和氟康唑对耐药念珠菌及耳念珠菌的体外作用。方法于2022年3—6月,采用美国临床实验室标准研究所M27-A3微量稀释法和微量肉汤稀释棋盘技术研究依维莫司联合伊曲康唑、伏立康唑、泊沙康唑及氟康唑对耐药念珠菌及耳念珠菌的体外治疗作用。通过测定最低抑菌浓度(MIC)和部分抑菌浓度指数来确定协同效应。结果依维莫司单药治疗22株耐药念珠菌及10株耳念珠菌的MIC为0.250~4.000 mg/L、1.000 mg/L,伊曲康唑、伏立康唑、泊沙康唑、氟康唑单独使用对22株耐药念珠菌MIC范围分别为0.125~4.000 mg/L、<0.125~2.000 mg/L、0.063~2.000 mg/L、1.000~64.000 mg/L,伊曲康唑、伏立康唑、泊沙康唑单独使用对10株耳念珠菌MIC范围分别为0.500~2.000 mg/L、0.125~8.000 mg/L、0.125~1.000 mg/L。当依维莫司与伊曲康唑、伏立康唑、泊沙康唑、氟康唑联合使用时,对耐药念珠菌的协同作用分别是9株(40.90%)、4株(18.18%)、8株(36.36%)、9株(40.90%)。当依维莫司联合唑类作用于耳念珠菌,未发现任何拮抗作用。结论依维莫司单独使用对耐药念珠菌及耳念珠菌菌株具有明显抗真菌作用,同时依维莫司联合唑类作用于耐药念珠菌时,表现出良好的协同作用,且没有拮抗作用,其进一步提升其抗耐药念珠及耳念珠菌的作用。

高浓度苯酚降解菌Candida tropicalis Z-04的鉴定及其对苯酚降解条件的优化

从降解苯酚的好氧颗粒污泥中筛选出一株苯酚降解菌,该菌株最高可耐受2.0 g/L的苯酚。依据形态特征和内源转录间隔区(ITS)的核酸序列分析,将该菌株鉴定为热带假丝酵母菌(Candida tropicalis),并命名为Candida tropicalis Z-04。采用中心复合设计(CCD)法对Candida tropicalis Z-04降解苯酚的条件进行合理设计,利用Design-Expert软件对试验数据进行分析,考察了各因素及其交互作用对苯酚降解率的影响,并得到苯酚最佳降解条件。结果表明,Candida tropicalis Z-04降解苯酚的最佳条件为:酵母提取物投加量0.41 g/L,苯酚初始质量浓度1.03 g/L,菌种投加量1.43%(体积分数),温度30.04℃。在此条件下苯酚的理论预测降解率可达到最大值99.10%。

代谢工程改造热带假丝酵母生产鼠尾草酸

鼠尾草酸(carnosic acid,CA)是一种酚类二萜化合物,广泛存在于鼠尾草等唇科类植物中。CA具有抗肿瘤等多种生理以及药理活性,在日化、食品、医疗领域应用价值巨大。热带假丝酵母具有鲁棒性强、耐高温、产油脂等特性,因而在萜类化合物高效生产方面极具潜力。该研究根据热带假丝酵母密码子偏好性对来源于鼠尾草的铁锈醇合酶基因CYP76AH24和鼠尾草酸合酶基因CYP76AK6、来源于拟南芥的细胞色素还原酶基因ATR1进行全序列密码子优化以及基因合成。以生产鼠尾草酸前体次丹参酮二烯热带假丝酵母1C2PM04作为出发菌株,将上述基因整合到其基因组中成功合成鼠尾草酸。利用模块化工程与酵母不同亚细胞区室的空间组合,将上述3条基因以模块化的方式导入胞质和过氧化物酶体中进行表达,鼠尾草酸产量分别为10.25 mg/L和4.64 mg/L。通过下调角鲨烯合酶基因ERG9,降低法尼基焦磷酸池的消耗进而改变代谢通量进一步提高鼠尾草酸产量,效价达到26.3 mg/L。将细胞色素P450酶和细胞色素还原酶进行融合表达,测试以刚性linker(E3AK,E3AK×2,E3AK×3)和柔性linker(G4S,G4S×2,G4S×3)为连接肽,融合表达CYP76AH24和ATR1,鼠尾草酸产量提高1.54倍。该文通过增加CPR拷贝数,增加电子供体,进一步提高鼠尾草酸表达水平,产量达到78.24 mg/L。