Distribution Characteristics of Drug Susceptibility Test Results of Tuberculosis and Non-Tuberculous Bacilli in Patients with Opportunistic Infections of AIDS

Objective: To understand the distribution of drug susceptibility test results of opportunistic infections of tuberculosis and non-tuberculous bacilli in AIDS patients. Methods: The AIDS patients who were hospitalized in our hospital from January 2016 to June 2019 were collected as the research objects, and patients with opportunistic tuberculosis and non-tuberculous bacilli from AIDS patients were screened for drug susceptibility tests, and the distribution characteristics of drug susceptibility were analyzed. Results: 179 strains of tuberculosis and non-tuberculous mycobacteria were isolated from the specimens of AIDS patients, including 135 cases of tuberculosis mycobacteria and 44 cases of non-tuberculous mycobacteria. In the results of the drug susceptibility test, most strains of Mycobacterium tuberculosis showed sensitivity to commonly used drugs, and a few strains showed resistance;most strains of non-tuberculous mycobacteria showed resistance, and a few strains showed sensitivity. Conclusion: AIDS opportunistic infection of Mycobacterium tuberculosis and non-tuberculous mycobacteria have significant differences in drug sensitivity test results. Timely detection and analysis are of great significance to the diagnosis and treatment of the disease.

Preliminary Study on Drug Susceptibility Profile and Resistance Mechanisms to Macrolides of Clinical Isolates of Non-tuberculous Mycobacteria from China

Objective Macrolide susceptibility and drug resistance mechanisms of clinical non-tuberculous mycobacteria（NTM） isolates were preliminarily investigated for more accurate diagnosis and treatment of the infection in China. Methods Four macrolides, including clarithromycin（CLAR）, azithromycin（AZM）, roxithromycin（ROX）, and erythromycin（ERY）, were used to test the drug susceptibility of 310 clinical NTM isolates from six provinces of China with the broth microdilution method. Two resistance mechanisms, 23 S r RNA and erm, were analyzed with nucleotide sequence analysis. Results Varied effectiveness of macrolides and species-specific resistance patterns were observed. Most Mycobacterium abscessus subsp. massiliense were susceptible and all M. fortuitum were highly resistant to macrolides. All the drugs, except for erythromycin, exhibited excellent activities against slow-growing mycobacteria, and drug resistance rates were below 22.2%. Only four highly resistant strains harbored 2,058/2,059 substitutions on rrl and none of other mutations were related to macrolide resistance. G2191 A and T2221 C on rrl were specific for the M. abscessus complex（MABC）. Seven sites, G2140 A, G2210 C, C2217 G, T2238 C, T2322 C, T2404 C, and A2406 G, were specifically carried by M. avium and M. intracellulare. Three sites, A2192 G, T2358 G, and A2636 G, were observed only in M. fortuitum and one site G2152 A was specific for M. gordonae. The genes erm（39） and erm（41） were detected in M. fortuitum and M. abscessus and inducible resistance was observed in relevant sequevar. Conclusion The susceptibility profile of macrolides against NTM was demonstrated. The well-known macrolide resistance mechanisms, 23 S r RNA and erm, failed to account for all resistant NTM isolates, and further studies are warranted to investigate macrolide resistance mechanisms in various NTM species.

Mycobacterium smegmatis enhances shikonin-induced immunogenic cell death—an efficient in situ tumor vaccine strategy

Tumor vaccines are a promising avenue in cancer immunotherapy.Despite the progress in targeting specific immune epitopes,tumor cells lacking these epitopes can evade the treatment.Here,we aimed to construct an efficient in situ tumor vaccine called Vac-SM,utilizing shikonin(SKN)to induce immunogenic cell death(ICD)and Mycobacterium smegmatis as an immune adjuvant to enhance in situ tumor vaccine efficacy.SKN showed a dose-dependent and time-dependent cytotoxic effect on the tumor cell line and induced ICD in tumor cells as evidenced by the CCK-8 assay and the detection of the expression of relevant indicators,respectively.Compared with the control group,the in situ Vac-SM injection in mouse subcutaneous metastatic tumors significantly inhibited tumor growth and distant tumor metastasis,while also improving survival rates.Mycobacterium smegmatis effectively induced maturation and activation of bone marrow-derived dendritic cells(DCs),and in vivo tumor-draining lymph nodes showed an increased maturation of DCs and a higher proportion of effector memory T-cell subsets with the Vac-SM treatment,based on flow cytometry analysis results.Collectively,the Vac-SM vaccine effectively induces ICD,improves antigen presentation by DCs,activates a specific systemic antitumor T-cell immune response,exhibits a favorable safety profile,and holds the promise for clinical translation for local tumor immunotherapy.

Molecular Identification of Mycobacterium Strains Responsible of Bovine Tuberculosis Cases in Bobo-Dioulasso Slaughterhouse, Burkina Faso

Bovine tuberculosis (bTB) is an endemic zoonosis significantly affects animal health in Burkina Faso. The primary causative agent is Mycobacterium tuberculosis (M. tuberculosis) complex, mainly M. bovis. Cattle are considered as natural reservoir of M. bovis. However, in Burkina Faso, the circulation of these strains remains poorly understood and documented. This study aimed to identify and characterize Mycobacterium strains from suspected carcasses during routine meat inspection at Bobo-Dioulasso refrigerated slaughterhouse. A prospective cross-sectional study was conducted from January 2021 to December 2022 on cases of seizures linked to suspected bovine tuberculosis. Microbiological and molecular analyzes were used for mycobacterial strain isolation and characterization. Out of 50 samples, 24% tested positive by microscopy and 12% by culture. Molecular analysis identified 6 strains of Mycobacteria, exclusively Mycobacterium bovis specifically the subspecies bovis (Mycobacterium bovis subsp bovis). In conclusion, M. bovis subsp bovis is the primary agent responsible for bovine tuberculosis in Bobo-Dioulasso. Continuous monitoring of mycobacterial strains is therefore necessary for the effective control of this pathology in the local cattle population.

EmbB and EmbC regulate the sensitivity of Mycobacterium abscessusto echinomycin

Treatment of Mycobacterium abscessus(Mab)infections is very challenging due to its intrinsic resistance to most available drugs.Therefore,it is crucial to discover novel anti-Mab drugs.In this study,we explored an intrinsic resistance mechanism through which Mab resists echinomycin(ECH).ECH showed activity against Mab at a minimum inhibitory concentration(MIC)of 2μg/ml.A embC strain in which the embC gene was knocked out showed hypersensitivity to ECH(MIC:0.0078-0.0156μg/ml).The MICs of ECH-resistant strains screened with reference to AembC ranged from 0.25 to 1μg/ml.Mutations in EmbB,including D306A,D306N,R350G,V555l,and G581S,increased the Mab's resistance to ECH when overexpressed in AembC individually(MIC:0.25-0.5μg/ml).These EmbB mutants,edited using the CRISPR/Cpf1 system,showed heightened resistance to ECH(MIC:0.25-0.5μg/ml).The permeability of these Mab strains with edited genes and overexpression was reduced,as evidenced by an ethidium bromide accumulation assay,but it remained significantly higher than that of the parent Mab.In summary,our study demonstrates that ECH exerts potent anti-Mab activity and confirms that EmbB and EmbC are implicated in Mab's sensitivity to ECH.Mutation in EmbB may partially compensate foralossof EmbCfunction.

Epidemiology and Clinical Features of Mycobacterium avium Complex Pulmonary Disease in a Brazilian Amazon Cohort

The incidence of Mycobacterium avium complex pulmonary disease (MACPD) has been globally increasing. The present study aims to provide a comprehensive analysis of clinical characteristics and treatment response among patients in the Amazon region of Brazil and conduct a retrospective cohort study at a prominent referral hospital in the State of Par, Brazil, from 2012 to 2020. The M. avium group represented 58.9% of cases, followed by M. intracellulare (35.7%), M. colombiense (3.6%), and M. chimaera (1.8%). The majority of patients (73.2%) were female and with an average age of 63 years. Primary clinical manifestations included persistent cough and sputum production. The Charlson comorbidity index (CCI) averaged 2.47, with 36.3% of patients having a CCI score equal to higher than 3. Notably, over 70% of patients had received treatment for pulmonary tuberculosis before initiating treatment for MAC infection. The fibrocavitary radiologic form was the most prevalent (55.4%), frequently exhibiting a bilateral distribution (53.6%). Antimicrobial susceptibility revealed a significant prevalence of MAC resistance to drugs in the therapeutic regimen. Despite this, most of the patients experienced clinical improvement (50%). In conclusion, this study highlights a higher prevalence of MAC infections among middle-aged women, with a history of pulmonary tuberculosis treatment and presenting the fibrocavitary radiological form was predominant.

Inferring Mycobacterium Tuberculosis Drug Resistance and Transmission using Whole-genome Sequencing in a High TB-burden Setting in China

Objective China is among the 30 countries with a high burden of tuberculosis(TB)worldwide,and TB remains a public health concern.Kashgar Prefecture in the southern Xinjiang Autonomous Region is considered as one of the highest TB burden regions in China.However,molecular epidemiological studies of Kashgar are lacking.Methods A population-based retrospective study was conducted using whole-genome sequencing(WGS)to determine the characteristics of drug resistance and the transmission patterns.Results A total of 1,668 isolates collected in 2020 were classified into lineages 2(46.0%),3(27.5%),and 4(26.5%).The drug resistance rates revealed by WGS showed that the top three drugs in terms of the resistance rate were isoniazid(7.4%,124/1,668),streptomycin(6.0%,100/1,668),and rifampicin(3.3%,55/1,668).The rate of rifampicin resistance was 1.8%(23/1,290)in the new cases and 9.4%(32/340)in the previously treated cases.Known resistance mutations were detected more frequently in lineage 2 strains than in lineage 3 or 4 strains,respectively:18.6%vs.8.7 or 9%,P<0.001.The estimated proportion of recent transmissions was 25.9%(432/1,668).Multivariate logistic analyses indicated that sex,age,occupation,lineage,and drug resistance were the risk factors for recent transmission.Despite the low rate of drug resistance,drug-resistant strains had a higher risk of recent transmission than the susceptible strains(adjusted odds ratio,1.414;95%CI,1.023–1.954;P=0.036).Among all patients with drug-resistant tuberculosis(DR-TB),78.4%(171/218)were attributed to the transmission of DR-TB strains.Conclusion Our results suggest that drug-resistant strains are more transmissible than susceptible strains and that transmission is the major driving force of the current DR-TB epidemic in Kashgar.

Tuberculosis in the Carcinal Environment in Chad Due to the Mycobacterium Tuberculosis Circulante Complex

Tuberculosis (TB) is a serious infectious disease and its control is considered a challenge, particularly among vulnerable populations such as prisoners. The prevalence of TB in prisons is an alarming public health problem in many countries. The aim of this study is to describe the epidemiology of tuberculosis and the strategies for controlling this disease in the Chadian prison population. During the course of our study, the prevalence of tuberculosis in prisons was 9.64%. The age group between 55 years and over (43.33%) was the most represented in this study, and all patients were men with a frequency of 62.66%. The cross-tabulation of Culture_7H9G and Culture_7H9P showed that out of our total positive sample, we found a total of 87 positive strains and 63 negative strains. Our study shows that it is essential to know the prevalence of tuberculosis in all the country’s prisons. Indeed, this can serve as an indication of the need for action in prisons to reduce TB rates, in particular by improving the structure of prison environments, diagnosing new cases quickly and accurately, identifying drug-resistant strains and implementing effective, direct treatment observed in people with tuberculosis.

Early Prosthetic Valve Endocarditis with Mycobacterium Tuberculosis after Mitral Valve Replacement: A Case Report

Background: Tuberculous endocarditis is a rare but serious complication of heart valve replacement surgery. We report the case of a 24-year-old patient, who presented with tuberculous endocarditis after mechanical mitral valve replacement, with a favorable clinical course following anti-tuberculosis treatment. Case Presentation: We report a 24-year-old male patient, admitted to the cardiac surgery department of the Fann Hospital (Dakar, Senegal), for the management of severe mixed (rheumatic and endocarditic) mitral insufficiency with associated tricuspid insufficiency. He had a history of recurrent angina and polyarthralgia in childhood, was hospitalized several times for refractory global cardiac decompensation, and for a suspected infective endocarditis a month before his admission. On admission, the clinical examination revealed signs suggestive of mitral and tricuspid insufficiency. Transthoracic echocardiography revealed severe post-endocarditic mitral insufficiency with A3 amputation, highly mobile 15 mm vegetations on the free edge of the large valve, moderate tricuspid insufficiency, and severe pulmonary artery hypertension. Mechanical mitral valve replacement and tricuspid valve annuloplasty using autologous pericardial strip were performed via median sternotomy. After ten days, the patient presented with global cardiac decompensation associated with a clinico-biological infectious syndrome, and tans-oesophageal echography revealed an abscess at the sinotubular junction, communicating with the aorta. A thoraco-abdomino-pelvic CT scan was done, which revealed a bilateral alveolar-interstitial syndrome with mediastinal lymphadenopathy. Anti-tuberculosis treatment with RHZE was initiated for 06 months. The clinical course was favorable. Conclusion: Tuberculous endocarditis in prostheses is a serious complication of heart valve replacement surgery, which may evolve favorably under medical treatment.

Mycobacterium gordoniasis of the cervical lymph nodes:A case report

BACKGROUND Owing to the advancement in bacterial identification techniques,the detection rate of non-tuberculous mycobacterium(NTM)has been on the rise.Different from Mycobacterium tuberculosis,the clinical symptoms of NTM are not easily detected,and the clinical efficacy and prognosis are somewhat heterogeneous.To report a case of Mycobacterium gordoniasis of cervical lymph node diagnosed in Anhui Chest Hospital in July 2022.CASE SUMMARY Upon examination,the patient who weighed 67.5 kg,was human immunodeficiency virus negative,healthy,without hypertension,diabetes,heart disease and other basic diseases microscopic analysis revealed granulomatous inflammation with coagulation necrosis in the lymphocyte,and tuberculosis was not ruled out.Plain computed tomography scans of the neck and chest indicated the presence of a single grayish-yellow and grayish-brown tissue,the dimensions of which was top of form 10.5 cm×3.0 cm×1.5 cm.After pathological consultation in our hospital,the diagnosis was confirmed as NTM infection.CONCLUSION This case report and the clinical epidemiological research on improving NTM have important guiding significance for improving decision-making in clinical treatments.

Metagenomic next-generation sequencing may assist diagnosis of osteomyelitis caused by Mycobacterium houstonense:A case report

BACKGROUND Mycobacterium houstonense(M.houstonense)belongs to the nontuberculous mycobacterium group.Infection caused by M.houstonense is prone to recurrence.CASE SUMMARY We present a patient who was diagnosed with osteomyelitis caused by M.houstonense and treated with a combination of cefoxitin,and amikacin combined with linezolid.CONCLUSION The emergence of metagenomic next-generation sequencing(NGS)has brought new hope for the diagnosis and treatment of listeria meningitis.NGS can analyze a large number of nucleic acid sequences in a short time and quickly determine the pathogen species in the sample.Compared with traditional cerebrospinal fluid culture,NGS can greatly shorten the diagnosis time and provide strong support for the timely treatment of patients.Regarding treatment,NGS can also play an important role.Rapid and accurate diagnosis can enable patients to start targeted treatment as soon as possible and improve the treatment effect.At the same time,by monitoring the changes in pathogen resistance,the treatment plan can be adjusted in time to avoid treatment failure.

Overlapping infections of Mycobacterium canariasense and Nocardia farcinica in an immunocompetent patient:A case report

BACKGROUND Infections by non-tuberculous mycobacteria(NTM)have become more common in recent years.Mycobacterium canariasense(M.canariasense)was first reported as an opportunistic pathogen in 2004,but there have been very few case reports since then.Nocardia is a genus of aerobic and Gram-positive bacilli,and these species are also opportunistic pathogens and in the Mycobacteriales order.Conventional methods for diagnosis of NTM are inefficient.Metagenomic next-generation sequencing(mNGS)can rapidly detect many pathogenic microorganisms,even rare species.Most NTM and Nocardia infections occur in immunocompromised patients with atypical clinical symptoms.There are no previous reports of infection by M.canariasense and Nocardia farcinica(N.farcinica),especially in immunocompetent patients.This case report describes an immunocompetent 52-year-old woman who had overlapping infections of M.canariasense,N.farcinica,and Candida parapsilosis(C.parapsilosis)based on mNGS.CASE SUMMARY A 52-year-old woman presented with a productive cough and chest pain for 2 wk,and recurrent episodes of moderate-grade fever for 1 wk.She received antibiotics for 1 wk at a local hospital,and experienced defervescence,but the productive cough and chest pain persisted.We collected samples of a lung lesion and alveolar lavage fluid for mNGS.The lung tissue was positive for M.canariasense,N.farcinica,and C.parapsilosis,and the alveolar lavage fluid was positive for M.canariasense.The diagnosis was pneumonia,and application of appropriate antibiotic therapy cured the patient.CONCLUSION Etiological diagnosis is critical for patients with infectious diseases.mNGS can identify rare and novel pathogens,and does not require a priori knowledge.

Mutation Characteristics of inhA and katG Genes in Isoniazid-Resistant Mycobacterium Tuberculosis Patients in Xinjiang

Objective:To analyze the mutation characteristics of inhA and katG genes in isoniazid-resistant Mycobacterium tuberculosis in Xinjiang.Methods:The katG and inhA in 148 strains of isoniazid-resistant Mycobacterium tuberculosis were amplified through fluorescence quantitative PCR,and the amplified products were sequenced and compared.Results:The inhA gene mutation rate of 148 strains of isoniazid-resistant mycobacterium tuberculosis was 13.51%(20/148),among which the inhA gene mutation rate among patients of Han,Uygur,and Kazakh ethnicity were 15.87%,13.21%,and 17.65%,respectively.There was no significant difference in the inhA mutation rate among nationalities(c^(2)=2.897,P>0.05).The mutation rate of the katG gene was 84.46%(125/148),among which the mutation rates of patients of Han,Uyghur,and Kazak ethnicities were 82.54%,84.91%,and 76.47%,respectively.The Hui and other ethnic groups were all affected by the katG gene mutation.There was no significant difference in the mutation rate of the katG gene among different ethnicities(c^(2)=3.772,P>0.05).The mutation rates of the inhA gene in southern Xinjiang,northern Xinjiang,and other provinces were 18.60%,9.28%,and 37.50%,respectively.The mutation rates of the inhA gene in different regions were statistically different(c^(2)=6.381,P<0.05).There was no significant difference in the inhA mutation rate between patients from southern and northern Xinjiang(c^(2)=2.214,P>0.05)and between southern Xinjiang and other provinces(c^(2)=1.424,P>0.05).However,the mutation rate of the inhA gene in patients from other provinces was higher than that in northern Xinjiang(c^(2)=5.539,P<0.05).The mutation rates of the katG gene in southern Xinjiang,northern Xinjiang,and other provinces were 81.40%,87.63%,and 62.50%,respectively.There was no significant difference in the mutation rates of the katG gene among different regions(c^(2)=3.989,P>0.05).Conclusion:katG gene mutation was predominant in isoniazid-resistant tuberculosis patients in Xinjiang Uygur Autonomous Region,and inhA and katG gene mutation were no different among different ethnic groups.

Mycobacterium Phlei在黄铁矿和方铅矿表面的选择性吸附作用机理

运用吸附量测定、ζ-电位研究、红外光谱和X射线光电子能谱分析,探讨Mycobacterium Phlei在黄铁矿和方铅矿表面的选择性吸附作用机理。结果表明,在其他实验条件固定的情况下,当溶液的初始pH值大于5时,Mycobacterium Phlei在黄铁矿表面的吸附量远远大于方铅矿;静电作用不是致使Mycobacterium Phlei在黄铁矿和方铅矿表面产生选择性吸附的主要作用力;Mycobacterium Phlei细胞表面的C、N和O元素通过矿物表面的Fe,Pb和S元素与矿物表面发生了化学吸附,而且与黄铁矿表面元素的作用程度大于方铅矿。矿物的表面结构及其性质、细胞表面基团与矿物表面金属离子的键合作用大小可能是致使Mycobacterium Phlei产生选择性吸附的主要原因。

Mycobacterium phlei菌对重金属Pb^(2+),Zn^(2+),Ni^(2+),Cu^(2+)的吸附规律

研究了Mycobacteriumphlei菌株分别对水相中重金属离子Pb2+,Zn2+,Ni2+,Cu2+的吸附规律·结果表明,Mycobacteriumphlei菌株对水相中的这四种重金属离子均有一定的吸附作用;吸附过程均在10min内就达到平衡;pH对吸附过程影响较大,在pH=3 0～4 0时,Mycobacteriumphlei菌对这四种金属离子吸附效果最好;温度升高对Pb2+,Ni2+和Cu2+的吸附过程不利,但Mycobacteriumphlei菌对Zn2+的吸附则是一个吸热过程·重金属离子在Mycobacteriumphlei菌上的吸附的选择性大小的顺序为:Pb2+>Zn2+>Cu2+>Ni2+·

分枝杆菌Mycobacterium ZLP生产雄烯二酮(4-AD)的优化工艺

利用正交实验对分枝杆菌降解植物甾醇生产雄烯二酮(4-AD)的发酵培养基进行优化,同时进行温度和pH的优化。结果表明:培养基的最佳组成为质量分数2.0%葡萄糖、2.0%蛋白胨、0.7%MgSO4、0.8%K2HPO4;最适温度28℃、最适pH 7.0,在此基础上发酵96 h,4-AD的产率可达到62.15%。

Mycobacterium E3休止细胞催化烯烃立体选择性环氧化

初步研究了MycobacteriumE3的生长和产酶特性，利用MycobacteriumE3休止细胞催化烷烃羟化和烯烃环氧化．研究结果表明，烷烃不能被羟化，烯烃环氧化具有底物选择性．对烯丙基型底物XCH2CH＝CH2（X＝H、Cl、Br、OH），取代基大小显著影响环氧化活性Mycobac-teriumE3中烯烃单加氧酶和另一种结构未知的酶的存在导致烯烃环氧化过程中存在环氧化物的立体选择性形成和非立体选择性降解两种竞争反应，旋光技术和手性气相色谱揭示MycobacteriumE3催化相应烯烃主要形成（R）-1，2-环氧丙烷和（S）-1-氯-2，3-环氧丙烷。

BYL-719对结核杆菌诱导异常破骨细胞分化的作用及机制

背景:PI3K/AKT信号通路调控破骨激活在维持骨稳态中具有关键作用,而骨关节结核中的骨质破坏正是由于结核杆菌感染引起的异常破骨细胞生成所致,但是PI3K信号通路在结核杆菌诱导的异常破骨细胞生成中发挥的作用尚不明确。目的:探究PI3K/AKT信号通路抑制剂BYL-719对结核杆菌诱导的异常破骨细胞生成的影响及机制。方法:使用牛结核杆菌卡介苗(BCG)感染RAW264.7细胞,Ag85B进行细胞免疫荧光染色;CCK-8法确定BYL-719安全使用浓度。实验分为空白对照组、BYL-719组、卡介苗组、卡介苗+BYL-719组。各组细胞在RANKL诱导下,通过抗酒石酸酸性磷酸酶染色和鬼笔环肽染色,探究BYL-719对结核杆菌感染后破骨细胞分化、融合的影响;RT-PCR和Western Blot检测破骨细胞相关基因及蛋白表达情况,并进一步探索作用机制。结果与结论:①免疫荧光染色结果显示,RAW264.7细胞吞噬结核杆菌;②CCK-8数据显示,40 nmol/L浓度BYL-719没有细胞毒性;③抗酒石酸酸性磷酸酶染色和鬼笔环肽染色提示,BYL-719能抑制结核杆菌感染后的破骨细胞生成、融合能力;④RT-PCR和Western blot结果也提示,BYL-719抑制了结核杆菌感染诱导的破骨细胞特异性基因(包括c-Fos、NFATc1、基质金属蛋白酶9和CtsK)表达升高(P<0.05);⑤Western blot和免疫荧光染色结果揭示,BYL-719通过下调IκBα-p65来抑制结核杆菌诱导的破骨细胞过度分化;⑥结论:BYL-719通过下调IκBα/p65抑制结核杆菌诱导的异常破骨细胞生成,说明IκBα/p65信号通路是骨关节结核潜在治疗靶点,BYL-719有预防和改善骨关节结核中骨质破坏的潜在价值。

Mycobacterium. sp BY11脱硫代谢产物的色谱分析

采用气质联用技术(GC-MS)和高效液相色谱技术(HPLC)对Mycobacterium sp. BY11柴油脱硫菌的二苯并噻吩(DBT)代谢途径进行了考察。GC-MS和HPLC结果表明,代谢产物中有2-羟基联苯(2-HBP)与2-甲氧基联苯(2-MBP)存在;2-MBP是DBT生物代谢的最终产物。以HPLC对该菌株的水相脱硫过程进行监测,3天后DBT脱除完全,达到了较好的脱硫效果。

Mycobacterium sp. BFZ304转化植物甾醇产9α-羟基雄烯二酮培养基的响应面优化

本研究以Mycobacterium sp.BFZ304作为实验菌株,研究了不同碳源、氮源、磷酸盐等培养基成分对Mycobacterium sp.BFZ304发酵转化植物甾醇生产9α-羟基雄烯二酮的影响。在单因素实验的基础上,以9α-羟基雄烯二酮的产量为衡量指标,采用响应面法优化了转化培养基的组成,并建立了玉米浆、葡萄糖、硝酸钠、磷酸氢二铵变化的二次回归方程,探讨了各因子对9α-羟基雄烯二酮产量的影响。最终确定最适宜的转化培养基为葡萄糖10 g/L、玉米浆40 g/L、硝酸钠6 g/L、磷酸氢二铵0.7 g/L。在此条件下,底物植物甾醇添加量为10 g/L时,9α-羟基雄烯二酮的产量可达到4.86 g/L,底物植物甾醇的转化率比优化前提高了近40%,具有极好的产业化前景。