Microbiology Commons^™

Amixicile Inhibits Anaerobic Bacteria Within An Oral Microbiome Derived From Patients With Chronic Periodontitis, Kane Ramsey

Theses and Dissertations

Periodontitis is a chronic inflammatory disease caused by pathogenic bacteria residing in a complex biofilm within a susceptible host. Amixicile is a non-toxic, readily bioavailable novel antimicrobial that targets strict anaerobes through inhibition of the activity of Pyruvate Ferredoxin Oxidoreductase (PFOR), a major enzyme mediating oxidative decarboxylation of pyruvate. Our study aimed to evaluate the efficacy of amixicile, when compared to metronidazole, in inhibiting the growth of bacteria present in a microbiome harvested from patients with chronic periodontitis.

Plaque samples were harvested from patients with severe chronic periodontitis and cultured under anaerobic conditions. The microbiomes were grown in the presence …

Readiness For Antimicrobial Resistance (Amr) Surveillance In Pakistan; A Model For Laboratory Strengthening, Dania Khalid Saeed, Rumina Hasan, Mahwish Naim, Afia Zafar, Erum Khan, Kauser Jabeen, Seema Irfan, Imran Ahmed Haq, Mohammad Zeeshan, Zabin Wajidali, Joveria Farooqi, Sadia Shakoor, Abdul Chagla, Jason Roy

Department of Pathology and Laboratory Medicine

Background: Limited capacity of laboratories for antimicrobial susceptibility testing (AST) presents a critical diagnostic bottleneck in resource limited countries. This paper aims to identify such gaps and to explore whether laboratory networks could contribute towards improving AST in low resource settings.
Methods: A self-assessment tool to assess antimicrobial susceptibility testing capacity was administered as a pre-workshop activity to participants from 30 microbiology laboratories in 3 cities in Pakistan. Data from public and private laboratories was analyzed and capacity of each scored in percentage terms. Laboratories from Karachi were invited to join a support network. A cohort of five laboratories that …

Reactivation Of Hiv-1 Proviruses In Immune-Compromised Mice Engrafted With Human Voa-Negative Cd4+ T Cells, Zhe Yuan, Guobin Kang, Wuxun Lu, Qingsheng Li

Nebraska Center for Virology: Faculty Publications

Background: HIV-1 infection remains incurable on antiretroviral therapy (ART) due to virus latency. To date, enhanced co-culture assays, including viral outgrowth assays (VOA), are commonly used to measure HIV-1 latent reservoirs and evaluate latency-reversing agents (LRAs). However, VOA can only reactivate a small fraction of intact proviruses.

Methods: To explore the utility of NOD scid gamma (NSG) mice as an in vivo model to reactivate HIV-1 proviruses from VOA-negative CD4+ T cells, resting CD4+ T cells from an HIV-1 latently infected individual were isolated and the human CD4+ T cells corresponding to VOA-positive and VOA-negative CD4+ T cells were engrafted …

Deciphering Fungal Dimorphism: Farnesol’S Unanswered Questions, Kenneth Nickerson, Audrey L. Atkin

Kenneth Nickerson Papers

Candida albicans excretes E,E-farnesol as a virulence factor and quorum sensing molecule that prevents the yeast to hyphal conversion. Polke et al. (2016) identified eed1Δ/Δ as the first farnesol hypersensitive mutant of C. albicans. eed1Δ/Δ also excretes 10X more farnesol and while able to form hyphae, it cannot maintain hyphae. This mutant enables new research into unanswered questions, including the existence of potential farnesol receptors and transporters, regulation of farnesol synthesis, and relationships among farnesol, germ tube formation and hyphal maintenance. The eed1 farnesol hypersensitivity can be explained by higher internal concentrations of farnesol or lower thresholds for response. One …

Studies Relating Pqq Biosynthesis To Putative Peptidases And Operon Structure In Pseudomonas Species, Benjamin Diaz

Theses and Dissertations--Plant and Soil Sciences

Several bacteria isolated from the broccoli rhizosphere were assayed to compare their ability to solubilize phosphate and release pyrroloquinoline quinone (PQQ) into the surrounding media. Subsequently, their genomes were sequenced and analyzed for PQQ biosynthesis operon structure. PQQ biosynthesis genes pqqA-F were found in all isolates. The order of PQQ biosynthesis genes and predicted amino acid sequences were compared to each other and the host’s ability to solubilize phosphate and release PQQ. In all Pseudomonas species, two putative protease genes, pqqF, and pqqG, flanked the canonical pqqA-pqqE biosynthesis operon. No mechanistic studies have confirmed the function of …

Using Extremophile Bacteriophage Discovery In A Stem Education Professional Development Partnership To Explore Model Classroom Research Experiences Integrating The Three Dimentions Of The Next Generation Science Standards, Carrie L. Boudreau Ms

All Student Scholarship

The National Research Council’s (NRC) A Framework for K-12 Science Education: Practices, Crosscutting Concepts, and Core Ideas describes a vision of what it means to be proficient in science. The project discussed in this thesis was developed with a NIH SEPA Grant 8R25OD010937 to the Virology and Electron Microscopy Laboratory at the University of Southern Maine (USM) under the direction of Dr. S. Monroe Duboise. The goal of the project was to explore using discovery of extreme environment bacteria and their bacteriophages as a model for using the three dimensions of learning to teach Next Generation Science Standards (NGSS). Specifically, …

The Role Of The Dosage Compensation Complex As A Pathway For Spiroplasma To Induce Male Lethality In Drosophila Melanogaster, Becky Cheng

CMC Senior Theses

Drosophila melanogaster and many other insects harbor intracellular bacterial symbionts that are transmitted vertically from infected host mothers to their offspring. Many of these bacteria alter host reproductive developmental processes in order to increase their transmission success. For example, Spiroplasma, a spirochete that naturally infects D. melanogaster, selectively kills males during mid-embryogenesis while sparing females. Previous studies suggested that Spiroplasma interacts genetically with the male-specific dosage compensation pathway, which causes ~2-fold up-regulation of most genes located on the male’s single X chromosome so that their expression matches the levels found in females who have two Xs. To further …

Characterization Of Phytocystatin-Like Cysteine Protease Inhibitors Of Trichomonas Vaginalis, Ryan Michael John Faucher

University of the Pacific Theses and Dissertations

Trichomoniasis is a common STD caused by the parasitic protozoan Trichomonas vaginalis. The parasite is estimated to have infected roughly 3.7 million Americans. Complications from trichomoniasis can lead to cervical cancer in women and prostate cancer in men. One of the mechanisms of the parasite employs is using cysteine proteases to break down the cellular matrix of its host. However, three endogenous phytocystatin-like protease inhibitors have been found within the parasite’s genome. By recombinantly expressing these cystatins we have been able to test their ability to inhibit cysteine proteases such as papain and those found in T. vaginalis to find …

Association Of Gut Luminal Metabolites And Allergic Responses, Ghaith Mohammed Fallata

Browse all Theses and Dissertations

Allergy is a global health problem, affecting more than 40% of the world population. Allergy is often associated with a dysregulation of the immune system that becomes overactive against allergens. Several genes are known to be important for the proper homeostasis of the immune system in the epithelial tissues, and the loss of function of genes such as IKKß or SOX9 impacts the interaction between external stimuli and the host. Many of the allergic responses are triggered through the regulatory cascade governed by transcriptional factor NF-κB. Regulation of NF-κB activity is complex, involves several alternative routes, and is also influenced …

Detection Of Antibiotic Resistance Loci In Wastewater And Fresh Water Samples, Mohammed Hamed Almalki

Masters Theses

Proper treatment of municipal wastewater is important not only for prevention of eutrophication but also for public health concerns. One consideration for wastewater treatment is the presence of organisms carrying antibiotic resistance genes. If these organisms survive the wastewater treatment process and are released into the streams, they can pose significant risks to public health. In addition, their presence also raises concerns for lateral gene transfer events at the wastewater plant. The spread of antibiotic loci has a major impact in public health and clinical therapy because resistant organisms render conventional treatments of important illnesses difficult. Beta-lactam drugs are known …

A Systems Biology Approach For Predicting Essential Genes And Deciphering Their Dynamics Under Stress In Streptococcus Sanguinis, Fadi El-Rami

Theses and Dissertations

Infectious diseases are the top leading cause of death worldwide. Identifying essential genes, genes indispensable for survival, has been proven indispensable in defining new therapeutic targets against pathogens, major elements of the minimal set genome to be harnessed in synthetic biology, and determinants of evolutionary relationships of phylogenetically distant species. Thus, essentiality studies promise valuable revenues that can decipher much of biological complexities.

Taking advantage of the available microbial sequences and the essentiality studies conducted in various microbial models, we proposed a framework for the prediction of essential genes based on our experimentally verified knowledge of the pathways involved in …

Expression Of Matrix Metalloproteinases In Naegleria Fowleri And Their Role In Degradation Of The Extracellular Matrix, Charlton Lam

Theses and Dissertations

Naegleria fowleri is a free-living amoeba found in freshwater lakes and ponds that is the causative agent of Primary Amoebic Meningoencephalitis (PAM). Matrix metalloproteinases (MMPs) have been described in protozoa, such as Plasmodium falciparum, Trypanosoma brucei, and Balamuthia mandrillaris, and have been linked to their increased motility and invasive capability by degrading components of the extracellular matrix (ECM). In addition, MMPs are often upregulated in tumorigenic cells and have been attributed as responsible for the metastasis of certain cancers. In the present study, in vitro experiments indicated that MMPs are linked functionally to the ECM degradation process. …

Plaster Creek Bacterial Monitoring And Source Tracking Project - Final Report, Randall J. Dejong

Faculty and Professional Research

The objective of this project was to identify important sources of bacterial loading in Plaster Creek (Kent County). The following goals were set to reach this objective: 1) the relative contributions of bacterial loading for 10 major tributaries will be assessed and the five most egregious contributors will be prioritized; 2) molecular markers will be used to try to identify the primary taxonomic sources, and 3) to pinpoint bacterial loading locations using molecular markers and scent-trained canines in sub-watersheds.

What's In A Name? New Bacterial Species And Changes To Taxonomic Status From 2012 Through 2015, Erik Munson, Karen C. Carroll

Clinical Lab Sciences Faculty Research and Publications

Technological advancements in fields such as molecular genetics and the human microbiome have resulted in an unprecedented recognition of new bacterial genus/species designations by the International Journal of Systematic and Evolutionary Microbiology. Knowledge of designations involving clinically significant bacterial species would benefit clinical microbiologists in the context of emerging pathogens, performance of accurate organism identification, and antimicrobial susceptibility testing. In anticipation of subsequent taxonomic changes being compiled by the Journal of Clinical Microbiology on a biannual basis, this compendium summarizes novel species and taxonomic revisions specific to bacteria derived from human clinical specimens from the calendar years 2012 through …

Tissue Specific Microenvironments: A Key Tool For Tissue Engineering And Regenerative Medicine, Patrick C. Sachs, Peter A. Mollica, Robert D. Bruno

School of Medical Diagnostics & Translational Sciences Publications

The accumulated evidence points to the microenvironment as the primary mediator of cellular fate determination. Comprised of parenchymal cells, stromal cells, structural extracellular matrix proteins, and signaling molecules, the microenvironment is a complex and synergistic edifice that varies tissue to tissue. Furthermore, it has become increasingly clear that the microenvironment plays crucial roles in the establishment and progression of diseases such as cardiovascular disease, neurodegeneration, cancer, and ageing. Here we review the historical perspectives on the microenvironment, and how it has directed current explorations in tissue engineering. By thoroughly understanding the role of the microenvironment, we can begin to correctly …

Characterization Of A Putative Hemolysin Expressed By Sneathia Amnii, A Preterm Birth-Associated Pathogen, Lizette Carrasco, Kimberly Jefferson

UROP Posters

The gram-negative bacteria Sneathia amnii is a poorly-characterized commensal of the female urogenital tract frequently associated with adverse clinical outcomes such as bacterial vaginosis (BV), amnionitis, and preterm labor. To investigate its potential role in virulence, we sought to identify and characterize virulence determinants produced by S. amnii in an effort to better understand the pathogenesis of infectious preterm birth. Through sequencing of the Sn35 genome (type strain of S. amnii), we identified two genes with amino acid sequence similarity and structural similarity to the filamentous hemagglutinin (FHA) protein of Bordetella pertussis and its Type Vb transporter. Because S. amnii …

Modeling Beta-Traces For Beta-Barrels From Cryo-Em Density Maps, Dong Si, Jing He

Computer Science Faculty Publications

Cryo-electron microscopy (cryo-EM) has produced density maps of various resolutions. Although ά-helices can be detected from density maps at 5-8 angstrom resolutions, β-strands are challenging to detect at such density maps due to close-spacing of β-strands. The variety of shapes of β-sheets adds the complexity of β-strands detection from density maps. We propose a new approach to model traces of β-strands for β-barrel density regions that are extracted from cryo-EM density maps. In the test containing eight β-barrels extracted from experimental cryo-EM density maps at 5.5 angstrom-8.25 angstrom resolution, StrandRoller detected about 74.26% of the amino acids in the β-strands …

Comparing An Atomic Model Or Structure To A Corresponding Cryo-Electron Microscopy Image At The Central Axis Of A Helix, Stephanie Zeil, Julio Kovacs, Willy Wriggers, Jing He

Computer Science Faculty Publications

Three-dimensional density maps of biological specimens from cryo-electron microscopy (cryo-EM) can be interpreted in the form of atomic models that are modeled into the density, or they can be compared to known atomic structures. When the central axis of a helix is detectable in a cryo-EM density map, it is possible to quantify the agreement between this central axis and a central axis calculated from the atomic model or structure. We propose a novel arc-length association method to compare the two axes reliably. This method was applied to 79 helices in simulated density maps and six case studies using cryo-EM …

Loss Of Outer Membrane Porins In Clonally Related Clinical Isolates Of Klebsiella Pneumoniae Modifies The Bacteria; Resulting In Altered Resistance To Phagocytosis By Macrophages, Debra Nickole Brunson

UNF Graduate Theses and Dissertations

Klebsiella pneumoniae is an opportunistic pathogen responsible for lobar pneumoniae, liver abscess, and septicemia. Clinical isolates are found to be extended spectrum beta lactamase positive with differential expression of the two classical porins, OmpK35 and OmpK36. Porin loss is associated with increased minimum inhibitory concentrations of beta lactam, cephalosporin, and carbapenem antibiotics that target the peptidoglycan. However, little is known about how porin loss affects other aspects of the cell envelope. The focus of this study was to characterize clinical isolates exhibiting differential porin expression and determine if the cumulative changes altered the resistance to phagocytosis by macrophages. The results …

Cellular Determinants Of Coronavirus Entry Routes, James Thomas Earnest

Dissertations

Coronaviruses (CoVs) represent some of the greatest modern threats to global health. CoVs are zoonotic viruses that generally cause respiratory or enteric infections. The ability of CoVs to move between species and into human populations ensures that CoVs will remain important and dangerous pathogens. Therefore, understanding how CoVs infect different hosts is vital to human health.

CoVs are enveloped and must undergo fusion of viral and host membranes to initiate infection. Viral glycoproteins, called Spike (S) proteins, are responsible for host cell binding and carrying out the membrane fusion reaction. S proteins store energy in their folded, pre-fusion conformation that …

Mutual Regulation Of Crp And N(Epsilon)-Lysine Acetylation In Escherichia Coli, Robert James Davis

Dissertations

Post-translational modifications, such as N(epsilon)-lysine acetylation, are known to alter the behavior of transcriptional regulators in eukaryotes, but very little is known about the consequences of acetylation on transcriptional regulation in bacteria. Here, I provide evidence that a global transcriptional regulator of carbon metabolism, cAMP Receptor Protein (CRP), promotes both enzymatic and non-enzymatic lysine acetylation in E. coli. Non-enzymatic lysine acetylation occurs when cells ferment acetate, such as during growth on high concentrations of glucose. Intriguingly, CRP can be non-enzymatically acetylated on several lysines, including lysine 100 (K100). I provide evidence that neutralization of the K100 positive charge, as would …

The Use Of Informativity In The Development Of Robust Viromics-Based Examinations, Siobhan C. Watkins, Catherine Putonti

Bioinformatics Faculty Publications

Metagenomics-based studies have provided insight into many of the complex microbial communities responsible for maintaining life on this planet. Sequencing efforts often uncover novel genetic content; this is most evident for phage communities, in which upwards of 90% of all sequences exhibit no similarity to any sequence in current data repositories. For the small fraction that can be identified, the top BLAST hit is generally posited as being representative of a viral taxon present in the sample of origin. Homology-based classification, however, can be misleading as sequence repositories capture but a small fraction of phage diversity. Furthermore, lateral gene transfer …

Phenotyping Temperature-Sensitive Coronaviruses, Amani Eddins

Master's Theses

Coronaviruses (CoVs) can cause a range of symptoms; from a mild common cold to life threatening acute respiratory distress syndrome (ARDS) upon infection. These emerging viruses have the ability to be highly pathogenic and detrimental to the human population. Two prime examples of CoV emergence, SARS-CoV (Severe Acute Respiratory Syndrome) and MERS-CoV, (Middle Eastern Respiratory Syndrome), which exhibits the pandemic potential of emerging CoVs that gain human tropism. Given the increasing potential of an emerging CoV outbreak there is a state of urgency to develop vaccines that will help protect the human population against current and future circulating strains. The …

Utilizing Genetic Techniques To Identify Amino Acids Within The Putative Glycosyltransferase Sypq That Are Essential For Its Role In Biofilm Formation By Vibrio Fischeri, Mary Kathryn Flaherty

Master's Theses

The polysaccharide component of the V. fischeri biofilm is produced by proteins encoded by the symbiosis polysaccharide (syp) locus. The syp locus encodes 18 genes, six of which are putative glycosyltransferases (GTs). One of these GTs, sypQ, encodes a putative family 2 glycosyltransferase (GT-2). The mechanism by which SypQ facilitates biofilm formation is not yet understood. To uncover which specific residues are essential for the function of SypQ, I utilized Bioinformatics, site-directed mutagenesis, and random mutagenesis. The Bioinformatics identified putative GT-2 motifs in the SypQ primary sequence. The mutagenesis (both site-directed and random), identified five residues (D95, D151, S153, D236, …

Optimizing Clean Catch Urine Collection And Its Applications In Urinary Microbiome Studies, Danielle Johansen

Master's Theses

Clean catch was developed before the advancement of more sensitive assays for culturing urinary bacteria. I reassessed clean catch, endeavoring to optimize this method. Periurethral swabs and voided urines were routinely collected, while analyzing different aspects of the method. I determined that midstream urine contained the least amount of vulvo-vaginal contamination and that the time of collection did not impact the results. I also determined that the use of antiseptic wipes prior to void increased the level of vulvo-vaginal contamination. A small cohort of females collected daily urines over a 17-day period and kept a strict alcohol diary. Females who …

Characterization Of Inhibitory Molecules Produced By Lactobacillus Crispatus, Giuseppe Anthony Pistone

Master's Theses

Lactobacillus species are widely accepted as beneficial bacteria of the human microbiota1-8. Lactobacilli spp. are well documented to inhibit pathogens by production and secretion of hydrogen peroxide (H2O2), organic acids, and/or proteinaceous bacteriocins into their environment. Most research attributes bactericidal activity of cell free supernatant (CFS) to H2O2 and/or lactic acid. Here, I demonstrate that CFS from a clinical isolate of Lactobacillus crispatus contains a molecule(s) that inhibits uropathogenic Escherichia coli (UPEC) colony formation independently of H2O2 and organic acids. Physiologic concentrations of H2O2 and organic acids produced by L. crispatus do not inhibit UPEC colony formation. Incubation of UPEC …

Carotenoids And Metabolism Of The Green Microalga Chlorococcum Sp. 8367re Under Stress Conditions, Kantima Janchot

Chulalongkorn University Theses and Dissertations (Chula ETD)

Green microalgae are one of the natural resources for productions of various and beneficial bioactive compounds, such as UV-screening compounds and carotenoids. This study focuses on the changes of carotenoids and metabolisms in the green microalga Chlorococcum sp. 8367RE under stress conditions. The results showed that stresses by salt, light, drought, and nitrogen starvation affected on alterations of morphological characteristics. Interestingly, size of cells culturing under salt stresses dramatically increased. It should be noted that KCl stress caused the enlargement of cell sizes approximately 5 folds. Carotenoids were identified and quantified by using ultra-high performance liquid chromatography (UHPLC) and mass …

Functional Characterization Of Natural Sunscreen Compound Mycosporine-2-Glycine From Extremophilic Cyanobacterium Halothece Sp. Pcc 7418 In Macrophage Cell Line And Fresh Water Cyanobacterium, Supamate Tarasuntisuk

Chulalongkorn University Theses and Dissertations (Chula ETD)

Mycosporine-2-glycine (M2G) is a rare UV-screening compound in a group of mycosporine-like amino acids (MAAs). This molecule is found in only two cyanobacteria; Euhalothece sp. LK-1 and Aphanothece halophytica (Halothece sp. PCC 7418). The structure of M2G composed of 4-deoxygadusol as a core structure, attached by 2 molecules of glycine at C1 and C3 positions. M2G has a maximal adsorption at 331 nm and a better antioxidative activity than other MAAs. Thus, it is interesting in determination of other activities for further cosmeceutical and pharmaceutical applications. In this study, a high purity M2G was successfully extracted and purified from Halothece …

โมโนโคลนอลแอนติบอดีต่อโปรตีน Vp1 ของไวรัสโลหิตจางในไก่ และการระบุเอพิโทป, เอกราช สิทธิเดช

Chulalongkorn University Theses and Dissertations (Chula ETD)

โรคโลหิตจางในไก่ เกิดจากไวรัส Chicken anemia virus (CAV) ไก่ที่ติดไวรัส จะมีภาวะโลหิตจางอย่างรุนแรงตัวแคระแกร็น ต่อมธัยมัสฝ่อ เซลล์ไขกระดูกลดลง และภูมิคุ้มกันบกพร่อง โปรตีน VP1 เป็นโปรตีนโครงสร้างของไวรัส ทำหน้าที่ในการรวมกันเป็นอนุภาคไวรัส มีคุณสมบัติในการเป็นแอนติเจน CAV งานวิจัยก่อนหน้านี้ สามารถผลิตรีคอมบิแนนท์โปรตีน Δ60N_VP1 ของไวรัสโลหิตจางในไก่ จึงเป็นที่มาของวัตถุประสงค์ของงานวิจัยนี้ คือ ผลิตโมโนโคลนอลแอนติบอดีต่อโปรตีน VP1 และ ระบุเอพิโทปต่อโมโนโคลนอลแอนติบอดี โดยนำม้ามที่ได้จากการใช้รีคอมบิแนนท์โปรตีน Δ60N_VP1 กระตุ้นภูมิคุ้มกันในหนูเม้าส์ มาหลอมรวมกับเซลล์ไมอีโลมา พบว่าได้ เซลล์ไฮบริโดมาที่ผลิตโมโนโคลนอลแอนติบอดีจำนวน 5 โคลน ได้แก่ โคลนที่ 1, 2, 3, 7 และ 21 สามารถจำแนกชนิดของแอนติบอดีได้เป็น IgG2a, IgM, IgG2b, IgM และ IgG1 ตามลำดับ การระบุเอพิโทป ทำโดยแบ่งชิ้นส่วนสารพันธุกรรม Δ60N_VP1 เป็น 6 ส่วน ได้แก่ Fragment 1(F1), F2, F3, F4 และ Separating 1(S1) และ S2 ซึ่งแยกมาจากชิ้น F1 จากนั้นเพิ่มปริมาณสารพันธุกรรมด้วยไพรเมอร์จำเพาะ และทำการย้ายชิ้นส่วนแต่ละชิ้นเข้าสู่เวกเตอร์ pET28a นำไปชักนำให้เกิดการแสดงออกใน E. coli Rosetta-gami รีคอมบิแนนท์โปรตีนแต่ละชนิดจะถูกใช้เป็นแอนติเจนเพื่อใช้ระบุเอพิโทปต่อโมโนโคลนอลแอนติบอดี ด้วยวิธี western blotting analysis ผลการทดลองพบโมโนโคลนอลแอนติบอดี ทั้ง 5 โคลน มีความจำเพาะต่อแอนติเจน Δ60N_VP1 และ ไม่เกิดปฏิกิริยาข้ามกับรีคอมบิแนนท์โปรตีนที่มี His-Tag ชนิดอื่น ในการศึกษานี้ใช้ โมโนโคลนอลแอนติบอดีชนิด IgG เท่านั้น ที่จะถูกนำไประบุเอพิโทป ผลการทดลองพบว่าโมโนโคลนอลแอนติบอดีโคลนที่ 1 ทำปฏิกริยาจำเพาะกับโปรตีน …

การคัดแยกยีสต์เพื่อผลิตน้ำมันจากไฮโดรไลเสตของใบอ้อย, รัชนา พระนิมิตร

Chulalongkorn University Theses and Dissertations (Chula ETD)

คัดแยกยีสต์จำนวน 106 ไอโซเลตจากจังหวัดระนอง ประเทศไทย คัดกรองยีสต์ที่สะสมน้ำมันภายในเซลล์สูงโดยการย้อมเซลล์ด้วยสีไนล์เรด (Nile red) พบว่ายีสต์จำนวน 24 ไอโซเลต มีหยดน้ำมันภายในเซลล์ มากกว่า 50% ของปริมาตรเซลล์ และเป็นยีสต์ที่สามารถใช้น้ำตาลไซโลสเป็นแหล่งคาร์บอนเพื่อการเจริญได้ 16 ไอโซเลต น้ำตาลไซโลสเป็นองค์ประกอบหลักในไฮโดรไลเสตใบอ้อยเช่นเดียวกับน้ำตาลกลูโคส ผลการวิเคราะห์ปริมาณน้ำมันที่สะสมภายในเซลล์ของยีสต์16 ไอโซเลตที่คัดกรองได้ โดยเลี้ยงในอาหารที่มีปริมาณกลูโคส 5% (น้ำหนัก/ปริมาตร) แต่มีปริมาณไนโตรเจนจำกัด พบว่าเป็นยีสต์โอลิจินัส (ยีสต์ซึ่งสะสมน้ำมันภายในเซลล์มากกว่า 20% น้ำหนัก/น้ำหนัก ของน้ำหนักแห้งเซลล์) จำนวน 5 สายพันธุ์ คือ Cryptococcus humicola NG2, Trichosporon mycotoxinivorans MG11-12.3, Cyberlindnera subsufficiens NG8.2, Rhodotorula mucilaginosa MG11-2.3 และ Yarrowia sp. NG17 ผลการวิจัยนี้นับเป็นการรายงานว่ายีสต์ T. mycotoxinivorans และ C. subsufficiens เป็นยีสต์โอลิจินัสเป็นครั้งแรก แต่เนื่องจากยีสต์ T. mycotoxinivorans เป็นยีสต์ก่อโรคจึงไม่นำมาศึกษาต่อ นำยีสต์ 4 สายพันธุ์ที่คัดกรองได้ มาผลิตน้ำมันโดยเลี้ยงในไฮโดรไลเสตใบอ้อยซึ่งมีปริมาณน้ำตาลกลูโคสและน้ำตาลไซโลสเท่ากับ 18.7 กรัม/ลิตร และ 19.1 กรัม/ลิตร โดยการปรับสภาพด้วยกรดซัลฟูริคเจือจางและย่อยต่อด้วยเอนไซม์เซลลูเลสทางการค้า ผลการเปรียบเทียบปริมาณน้ำมันที่ผลิตได้ในไฮโดรไลเสตใบอ้อยที่ผ่านการปรับด่างเกินเพื่อกำจัดสารยับยั้งการเจริญของยีสต์ และไม่ผ่านการปรับด่างเกิน พบว่ายีสต์ทั้ง 4 สายพันธุ์ผลิตน้ำมันในไฮโดรไลเสตใบอ้อยที่ไม่ผ่านการปรับด่างเกินได้มากกว่า โดย Yarrowia NG17 ผลิตน้ำมันสูงที่สุดเท่ากับ 10.15% น้ำหนัก/น้ำหนักของน้ำหนักเซลล์แห้ง ผลการหาภาวะที่เหมาะสมสำหรับการผลิตน้ำมันของ Yarrowia NG17 โดยแปรผันการเติมและไม่เติม แคลเซียมคลอไรด์ (CaCl2) โพแทสเซียมไดไฮโดรเจนฟอสเฟต (KH2PO4) และแมกนีเซียมซัลเฟต (MgSO4) ในไฮโดรไลเสตใบอ้อย พบว่ายีสต์ Yarrowia NG17 มีอัตราการผลิตน้ำมันสูงที่สุดเท่ากับ 1.52 กรัม/ลิตร/วัน เมื่อเจริญในไฮโดรไลเสตใบอ้อยที่ไม่เติมสารอาหารใดๆที่ทดสอบ ผลการแปรผันค่าพีเอชเริ่มต้นช่วง …