Bioprospecting in the Berkeley Pit: Extremophilic Microbes in Drug Discovery
Andrea Stierle is a natural products organic chemist who utilizes targeted bioassay guided fractionation to isolate secondary metabolites from source organisms. She earned her doctorate in Organic Chemistry from Montana State University where she discovered the first host specific toxin against the weed pest spotted knapweed and found that putative sponge metabolites can actually be produced by bacterial endosymbionts. With husband and collaborator Don Stierle she continued to study Bermudian sponge endosymbionts as sources for new bioactive agents and discovered a unique antibiotic that was also active against the AIDS virus.
As a Research Assistant Professor at Montana State University she discovered a fungus in the bark of the Pacific yew tree that produced paclitaxel in de novo fashion. This unique fungus – Taxomyces andreanae - was named after Andrea, its discoverer.
As a Research Professor at Montana Tech, a small mining college in Butte, Montana, she and Don began their exploration of the secondary metabolites of fungi and bacteria surviving and thriving in an abandoned acid mine waste lake. Berkeley Pit Lake is part of the largest EPA Superfund site in North America. It contains over 150 billion liters of metal sulfate rich, acidic “water” (pH 2.5) and sits at the headwaters of the Columbia River. With its low pH and high metal content, it was considered too toxic to support life. In 1995, however, Andrea began to isolate fungi and bacteria from water and sediment samples. Although conditions within the Pit Lake System were too toxic for “normal” aquatic biota, these same conditions provided an ideal environment for extremophiles which have proven to be a reservoir of bioactive secondary metabolites waiting to be discovered. The Stierle have isolated compounds with activity against non-small cell lung cancer, ovarian cancer, and leukemia from this collection.
As a Research Professor at the University of Montana, Andrea continues to work with Don to explore the secondary metabolites produced by these extremophiles. They are also studying the secondary metabolites of human gut microbes and Ayurvedic plants. They are currently focusing on the isolation of small molecule inhibitors of enzyme pathways associated with inflammatory processes and epithelial mesenchymal transition.
The Stierle Research Lab is dedicated to the isolation and structural characterization of compounds with potent, selected biological activity from both macro- and microorganisms. These include both traditional medicinal plants and microbes isolated from unusual ecological niches. We are currently studying two very different populations of microbes: those isolated from an acid mine waste lake in Butte, Montana, and those isolated from the human microbiome. We are also studying the bioactive components of Ayurvedic plants, and the biotransformation of those components by human gut microbes. Whatever the organism, plant or microbe or a combination of the two, it is extracted in organic solvents and a series of bioassays are used to determine the potential biological activities of these extracts. Signal transduction enzyme inhibition assays have been developed to target activity against specific disease conditions. Of particular interest are those diseases with a connection to chronic inflammation. These include many cancers, Alzheimer’s disease and autoimmune disorders. Using enzyme inhibition as a fractionation guide, we have isolated and elucidated several novel molecules that have shown potent, selective activity against specific cancers – ovarian, non-small lung and leukemia -- in the NIH 60 human cell-line assay.
We are also interested in targeting the antibiotic potential of these metabolites. We use a series of standard disk assays to guide the isolation of compounds with antifungal and antibacterial activity. The rising incidence of immunocompromised individuals has generated an array of emerging infectious diseases in critical need of prophylaxis. Of particular interest are those compounds with antifungal activity, as opportunistic mycoses are a growing problem in immunocompromised individuals, including AIDS patients and patients on immunosuppressive therapy. We are also collaborating with Dr. Allen Harmsen at Montana State University in the search for compounds with specific activity against Pneumocystis jirnoveci (formerly carinii). This unusual microbe was formerly classified as a protozoan but is now classified as a fungus. It is the causative agent of Pneumocystis carinii pneumonia, an insidious opportunistic infection in immunocompromised patients.
The Stierle lab is also looking at the potential of the Berkeley Pit Lake microbes to participate in the remediation of this 40 billion gallon acid mine waste lake that graces the northeast corner of Butte, Montana. These efforts have led to the isolation of an unusual yeast that sorbs metals even at pH 2.3.
The Stierle lab has long studied endosymbiotic microbes isolated from marine sponges and the inner bark of trees – notably the Northwest Pacific yew tree. The Stierles found that many compounds reported from sponge extracts might actually have been produced by their microbial symbionts. This work led to the discovery of a unique compound from a Bermudian sponge endosymbioticbacterium that showed activity against both pathogenic bacteria and the AIDS virus. The Stierles will work with collaborators at UM to determine how this compound affects the AIDS virus.
In the early 90’s The Stierles also searched for a fungal source of the drug taxol (paclitaxel), an anticancer agent which showed promise in clinical trials against refractory breast and ovarian cancers. Unfortunately the source organism of taxol, the northwest Pacific yew tree, had been clear-cut to the point of endangerment and could not supply the growing demands for taxol. It was clear that additional sources of taxol were necessary. Andrea isolated over 300 fungi from the inner bark and needles of yew trees in Montana, Washington, Idaho and Oregon. In 1993, the team published a report of a fungus isolated from the bark of the Pacific yew tree, Taxus brevifolia Nutt, which could produce taxol in de novo fashion. This unique fungus – Taxomyces andreanae - was named after Andrea, its discoverer. The Stierles hope to compare the production of taxol by the tree and the fungus.
Selected Publications – last ten years
Secondary Metabolites of Acid Mine Waste Fungi A Stierle, D Stierle 2017. In "Topics in Biodiversity and Conservation", D Hawksworth, RRM Patterson (Eds), Springer, pp.213-244.
The Ayurvedic plant Bacopa monnieri inhibits inflammatory pathways in the brain. Nemetchek MD, Stierle AA, Stierle DB, Lurie DI. J Ethnopharmacol. 2017 Feb 2;197:92-100.
CB2 receptors regulate natural killer cells that limit allergic airway inflammation in a murine model of asthma. Ferrini ME, Hong S, Stierle A, Stierle D, Stella N, Roberts K, Jaffar Z. Allergy 2016 [Epub ahead of print]
Azaphilones from an Acid Mine Extremophile Strain of a Pleurostomophora sp. Stierle AA, Stierle DB, Girtsman T, Mou TC, Antczak C, Djaballah H.J Nat Prod. 2015 Dec 24;78(12):2917-23. . Epub 2015 Dec 7.
Bioactive Secondary Metabolites Produced by the Fungal Endophytes of Conifers. Stierle AA, Stierle DB Nat Prod Commun. 2015 Oct;10 (10):1671-82. Related citation
Crystal structure and absolute configuration of preaustinoid A1. Stierle A, Stierle D, Decato D. Acta Crystallogr E Crystallogr Commun. 2015 Jul 22;71 (Pt 8):o596-7. eCollection 2015 Aug 1. Free full textRelated citations
Redetermination and absolute configuration of berkeleydione. Stierle A, Stierle D, Decato D Acta Crystallogr E Crystallogr Commun. 2015 Mar 21;71(Pt 4):o248. eCollection 2015 Apr 1. Free full text Related citations
Bioactive secondary metabolites from acid mine waste extremophiles.Stierle AA, Stierle DB. Nat Prod Commun. 2014 Jul;9(7):1037-44. Related citations
Phomopsolides and related compounds from the alga-associated fungus, Penicillium clavigerum. Stierle AA, Stierle DB, Mitman GG, Snyder S, Antczak C, Djaballah H. Nat Prod Commun. 2014 Jan;9(1):87-90. Related citations
Bioprospecting in the Berkeley Pit: the Use of Signal Transduction Enzyme Inhibition Assays to Isolate Bioactive Secondary Metabolites from the Extremophilic Fungi of an Acid Mine Waste Lake. Andrea Stierle and Donald Stierle. 2013 In: “Bioactive Natural Products” Atta-Ur-Rahman, Ed.; Elsevier Science Publishers: Amsterdam. pp. 1-47.
Caspase-1 inhibitors from an extremophilic fungus that target specific leukemia cell lines. Stierle AA, Stierle DB, Girtsman T. J Nat Prod. 2012 Mar 23;75(3):344-50. Epub 2012 Feb 1. PubMed Free full text Related citations
Caspase-1 and -3 inhibiting drimane sesquiterpenoids from the extremophilic fungus Penicillium solitum. Stierle DB, Stierle AA, Girtsman T, McIntyre K, Nichols J. J Nat Prod. 2012 Feb 24;75(2):262-6. Epub 2012 Jan 25. Free full text Cited in PMC Related citations
Berkeleyones and related meroterpenes from a deep water acid mine waste fungus that inhibit the production of interleukin 1-β from induced inflammasomes. Stierle DB, Stierle AA, Patacini B, McIntyre K, Girtsman T, Bolstad E J Nat Prod. 2011 Oct 28;74(10):2273-7. Free full text Cited in PMC Related citations
Anticancer compounds derived from fungal endophytes: their importance and future challenges. Kharwar RN, Mishra A, Gond SK, Stierle A, Stierle D. Nat Prod Rep. 2011 Jul;28(7):1208-28. Cited in PMC Related citations
The berkeleyamides, amides from the acid lake fungus Penicillum rubrum. Stierle AA, Stierle DB, Patacini B J Nat Prod. 2008 May;71(5):856-60. Cited in PMC Related citations
The berkeleyacetals, three meroterpenes from a deep water acid mine waste Penicillium. Stierle DB, Stierle AA, Patacini B. J Nat Prod. 2007 Nov;70(11):1820-3. Free full text Cited in PMC Related citations
Berkelic acid, a novel spiroketal with selective anticancer activity from an acid mine waste fungal extremophile. Stierle AA, Stierle DB, Kelly K. J Org Chem. 2006 Jul 7;71(14):5357-60. Cited in PMC Related citations
Bioprospecting in the Berkeley Pit:The Search for Valuable Natural Products from a Most Unnatural World. 2006. AA Stierle, Montana, the Magazine of Western History, 56(4):71.
Bioprospecting in the Berkeley Pit: Bioactive Metabolites from Acid Mine Waste Extremophiles A Stierle, D Stierle. 2005 In: “Bioactive Natural Products”, Volume 32, Atta-Ur-Rahman, Ed.; Elsevier Science Publishers: Amsterdam.
Novel sesquiterpenoid matrix metalloproteinase-3 inhibitors from an acid mine waste extremophile. Stierle AA, Stierle DB, Kemp K. J Nat Prod. 2004 Aug;67(8):1392-5. Cited in PMC Related citations
Berkeleydione and berkeleytrione, new bioactive metabolites from an acid mine organism. Stierle DB, Stierle AA, Hobbs JD, Stokken J, Clardy J Org Lett. 2004 Mar 18;6(6):1049-52. Cited in PMC Related citations
Complete Publication List
1. J.H. Cardellina II, G. Spotted Bear, J. Mitchell, and A.Stierle. Native American food and medicinal plants, 6. Antimicrobial acetylenic alcohols from Lomatium cous and Osmorhiza occidentalis. 1985. Proc. Mont.Acad.Sci., 45:130-133.
2. D.B. Stierle, A.A. Stierle, and R.D. Larsen. 1988. Phytochemistry 27:517-522.
3. A.C. Stierle, J.H. Cardellina II, and G.A. Strobel. Maculosin, a host specific phytotoxin for spotted knapweed from Alternaria alternata. 1988. Proc. Nat. Acad. Sci. USA. 85:8008.
4. A.C. Stierle, J.H. Cardellina II, and G.A. Strobel. Phytotoxins from Alternaria alternata, a pathogen of spotted knapweed. 1989. J. Nat. Prod. 52: 42.
5. A.C. Stierle, J.H. Cardellina II, and F.L. Singleton. A marine Micrococcus produces metabolites ascribed to the sponge Tedania ignis. 1988. Experientia 44:1021.
6. G.A. Strobel, A.A. Stierle, S.H. Park and J.H. Cardellina. Maculosin, a Host-Specific Phytotoxin from Alternaria alternata on Spotted Knapweed. In “Microbes and Microbial Products as Herbicides”. Ed., R.E. Hoagland.; ACS Symposium Series 439, ACS: Washington, DC, 1990; pp 53-62.
7. A.A. Stierle, R. Upadhyay, G.A. Strobel, J. Hershenhorn and G.C. Molina. Investigation of host selective phytotoxins of Mycosphaerella fijiensis, the causative agent of Black Sigatoka Disease of bananas and plantains. 1991. Experientia, 47(8): 853-858.
8. A.A. Stierle, R. Upadhyay and G.A. Strobel. Cyperine, a novel phytotoxin from Ascochyta cypericola, a pathogen of Cyperus rotundus. 1991. Phytochemistry 30:2191.
9. A. Stierle, G.A. Strobel, D Stierle and Fumio Sugawara. Analytical Methods for Phytotoxins. In "Methods of Plant Analysis"; Eds., H.F. Linskens and J.F. Jackson. Springer Verlag Press: Berlin, 1992, 1-32.
10. J.H. Cardellina, R.L. Hendrickson, A.A. Stierle and G.E. Martin. Kimbasines A and B, novel hexacyclic norsesterterpene alkaloids from the sponge Igernella notabilis. 1990. Tetrahedron Letters 32:2347.
11. A.A. Stierle and J.H. Cardellina. Benzothiazole derivatives from a putative symbiont of the marine sponge Tedania ignis. 1991. Tetrahedron Letters 32:4847-4848.
12. G.A. Strobel, A. Stierle and T.J.G.M. VanKuijk. Factors influencing the in vitro production of radiolabeled taxol by Pacific yew, Taxus brevifolia. 1992. Plant Science 84:65.
13. Joseph Hershenhorn, SangHo Park, Andrea Stierle and Gary Strobel, Gary. Fusarium avenaceum as a novel pathogen of spotted knapweed and its phytotoxins, acetamido-butenolide and enniatin B. 1992. Plant Science 86: 155-160.
14. D.B. Stierle and A.A. Stierle. Pseudomonic acid derivatives from a marine bacterium. 1992. Experientia 48(11-12) :1165-1169.
15. G.A. Strobel, A. Stierle, D. Stierle, W.M. Hess. Taxomyces andreanae, a proposed new taxon for a bulbilliferous hyphomycete associated with Pacific yew. 1993. Mycotaxon 47:71.
16. Andrea A. Stierle, Joseph Hershenhorn and Gary Strobel. Isolation of Zinniol-related Phytotoxins from Alternaria cichorii. 1993. Phytochemistry 32: 1145-1149.
17. Andrea Stierle, Gary Strobel and Donald Stierle. Taxol and taxane production by Taxomyces andreanae an endophytic fungus of Pacific yew. 1993. Science 260:214-216.
18. SangHo Park, Andrea Stierle, and Gary Strobel. Metabolism of maculosin, a host specific phytotoxin produced by Alternaria alternata on spotted knapweed (Centaurea maculosa L.). 1994. Phytochemistry 35(1):101-106.
19. Gary A. Strobel, Andrea Stierle and W.M. Hess. Taxol formation in yew - Taxus. 1993. Plant Science 92:1-12.
20. J. Hershenhorn, M. Vurro, M.C. Zonno, A. Stierle and G. Strobel. Septoria cirsii, a potential biocontrol agent of Canadian thistle and its phytotoxin - ß-nitropropionic acid. 1994. Plant Science 94:227-234.
21. X.Yang; G.Strobel; A.Stierle; W.M. Hess; J.Lee and J.Clardy. A fungal endophyte-tree relationship: Phoma sp. in Taxus wallachiana. 1994. Plant Science 102: 1-9.
22. G.Strobel; A.Stierle and W.M. Hess. The stimulation of taxol production in Taxus brevifolia by various growth retardants. 1994. Plant Science 101: 115-124.
23. Andrea Stierle, Donald Stierle, Gary Strobel, Gary Bignami and Paul Grothaus. Investigation of endophytic fungi of Pacific yew in "Bioregulators and Natural Products". Ed., P. Hedin, ACS Symposium Series 557, Washington, DC, 1994, 64-77.
24. Andrea Stierle, Donald Stierle, Gary Strobel, Gary Bignami and Paul Grothaus. Bioactive metabolites of the endophytic fungi of Pacific yew, Taxus brevifolia: paclitaxel, taxanes, and other bioactve compounds in “Taxane Anticancer Agents: Basic Science and Current Status”. Eds., G.I.Georg; T.T.Chen; I.Ojima and D.M.Vyas. ACS Symposium Series 583, Washington, DC, 1995, 81-97.
25. Andrea Stierle, Donald Stierle, Gary Strobel, Paul Grothaus and Gary Bignami. The search for a taxol-producing microorganism among the endophytic fungi of the Pacific yew, Taxus brevifolia. 1995. J.Nat. Prod. 58(9): 1315-1324.
26. Donald B. Stierle, Andrea A. Stierle and Barb Ganser. Phomopsolides from a Penicillium sp. 1997. J. Nat. Prod. 60(11): 1207-1209.
27. Donald B. Stierle, Andrea A. Stierle and Anita Kunz. Dihydroramulosin From Botrytis sp. 1998. J.Nat.Prod. 61(10):1277-1278.
28. Donald B. Stierle, Andrea A. Stierle, Tim Bugni, Greg Loewen. Gloeolactone, A New Epoxy Lactone From a Bluegreen Alga. 1998. J.Nat.Prod. 61(2):251-252.
29. D.B. Stierle, A.A. Stierle, and B. Ganser. Isolation of highly methylated fatty acid derivatives from a Penicillium sp. 1999. J.Nat.Prod., 62(8): 1147-1150.
30. Andrea Stierle, Donald Stierle and Timothy Bugni. Sequoiatones A and B: novel antitumor metabolites of a redwood endophyte. 1999. J.Org.Chem., 64(15): 5479-5484.
31. R.A.Wilkenson, G.Strobel and A Stierle. Sphaeric acid, a new succinic acid derivative from a Sphaeropsis sp. 1998. J.Nat. Prod. 62(2) : 358-360.
32. B.R. Niedens; S.R. Parker; D.B. Stierle and A.A. Stierle. 1999. First Fungal Aromatic L-amino Acid decarboxylase from a Paclitaxel-producing Penicillium raistrickii. Mycologia 91 (4): 619-625.
34. Stephen R. Parker; Andrea A. Stierle; Bret R. Niedens and Donald B. Stierle. 2000. Identification of an Aromatic Amino Acid Decarboxylase from a Yew-Associated Fungus. Intermountain Journal of Sciences, 6(3): 95-107.
35. Kosted, P.J., S.A. Gerhardt, A. Stierle and J.E. Sherwood. 2000. Structural requirements for activity of the mating pheromones of Ustilago hordei. Fung.Genet.Biol. 29:107-17.
36. Andrea A. Stierle and Donald B. Stierle. Bioactive compounds from four endophytic Penicillium sp. isolated from the northwest Pacific yew tree. In: “Bioactive Natural Products”, Atta-Ur-Rahman, Ed.; Elsevier Science Publishers: Amsterdam. Vol. 24. 2000, pp 933-978.
37. A. Stierle, D. Stierle, T. Bugni . 2001. Sequoiatones C-F, constituents of the redwood endophyte, Aspergillus parasiticus. J. Nat. Prod. 64: 1350-1353.
38. D. Stierle, A. Stierle, T. Bugni. 2003. Sequoiamonascins A-D : Novel Anticancer Metabolites Isolated from a Redwood Endophyte. J.Org.Chem. 68: 4966-4967.
39. Andrea A. Stierle, Donald B. Stierle, Keith Parker, Eric Goldstein, Tim Bugni, Chad Baarson, Julie Gress, Danielle Blake. 2003. A Novel 5-HT Receptor Ligand and Related Cytotoxic Compounds from an Acid Mine Waste Extremophile. J.Nat.Prod., 66: 1097-1100.
40. D.Stierle, A. Stierle, J.David Hobbs, Janalee Stokken, and J. Clardy. 2004. Berkeleydione and Berkeleytrione, New Bioactive Metabolites from an Acid Mine Organism. Organic Letters 6(6): 1049-1052.
41. A. Stierle, D. Stierle, and K. Kemp, 2004. Novel Sesquiterpenoid Matrix Metalloproteinase-3 Inhibitors from an Acid Mine Waste Extremophile. in August 2004 D.John Faulkner and Paul Scheurer memorial issue of J.Nat. Prod. 67(8): 1392-1395.
42. Andrea Stierle and Donald Stierle. Bioprospecting in the Berkeley Pit: Bioactive Metabolites from Acid Mine Waste Extremophiles. In: “Bioactive Natural Products”, Volume 32, Atta-Ur-Rahman, Ed.; Elsevier Science Publishers: Amsterdam. 2005.
43. A. Stierle, D. Stierle, and K. Kelley, 2006. Berkelic Acid, A Novel Spiroketal with Highly Specific Anti-tumor Activity from an Acid-Mine Waste Fungal Extremophile. 2006. J. Org. Chem. 71: 5357-5360.
44. Andrea Stierle, 2006. Bioprospecting in the Berkeley Pit: The Search for Valuable Natural Products from a Most Unnatural World. Montana, The Magazine of Western History. 56 (4): 71.
45. Stierle, D. B.; Stierle, A. A.; Patacini, B. 2007. The Berkeleyacetals, Three Meroterpenes from a Deep Water Acid Mine Waste Penicillium. J. Nat. Prod. 70(11); 1820-1823.
46. Andrea A. Stierle, Donald B. Stierle, Briana Patacini, 2008. The Berkeleyamides: Amides From the Acid Lake Fungus Penicillium rubrum. J. Nat. Prod. 71, 856-60.
47. R. N. Kharwar, A. Mishra, S. K. Gond, A.Stierle*, D.Stierle. 2011. Anticancer compounds derived from fungal endophytes: their importance and future challenges. Nat. Prod. Rep., 28 (7), 1208 – 1228.
48. DB. Stierle, AA. Stierle, B. Patacini, K. McIntyre, R. Girtsman, E. Bolstad. 2011. Berkeleyones and Related Meroterpenes From a Deep Water Acid Mine Waste Fungus That Inhibit the Production of Interleukin 1-β from Induced Inflammasomes J. Nat. Prod. 74, 2273–2277.
49 AA. Stierle, DB. Stierle, T. Girtsman. 2012. Caspase-1 Inhibitors from a Deep Water, Acid Mine Waste Extremophilic Fungus with Specific Cytotoxicity Towards Leukemia Cell Lines. J.Nat. Prod. 75, 344–350.
50. DB. Stierle, AA. Stierle, T. Girtsman, K. McIntyre, J. Nichols. 2012. Caspase-1 and Caspase-1 and 3 Inhibiting Drimane Sesquiterpenoids From the Extremophilic Fungus,Penicillium solitum. J. Nat. Prod. 75, 262–266
51. Andrea Stierle and Donald Stierle. April, 2013. Bioprospecting in the Berkeley Pit: the Use of Signal Transduction Enzyme Inhibition Assays to Isolate Bioactive Secondary Metabolites from the Extremophilic Fungi of an Acid Mine Waste Lake. In: “Bioactive Natural Products” Atta-Ur-Rahman, Ed.; Elsevier Science: Amsterdam. Vol. 39, pp 1-47
52. A.A. Stierle, D.B. Stierle, G.G. Mitman, S. Snyder, S, C. Antczak, H. Djaballah. 2014. Phomopsolides and related compounds from the alga-associated fungus, Penicillium clavigerum. Nat Prod Commun. 9 (1), 87-90.
53. A.A. Stierle, D.B. Stierle. 2014. Bioactive Secondary Metabolites of Acid Mine Waste Extremophiles. Nat. Prod. Commun., 9(7), 1037-1044.
54. A Stierle, D Stierle 2014 Bioactive Secondary Metabolites of Acid Mine Waste Extremophiles. Nat Prod Commun, 9(7), 1037-1044.
55. A Stierle, D Stierle, D Decato 2015 Redetermination and absolute configuration of berkeleydione. Acta Crystallographica Section E. Structure Reports Online. E71, o248.
56. A Stierle, D Stierle, D Decato 2015 Determination of the absolute configuration of preaustinoid A1. Acta Crystallographica Section E. Structure Reports Online. E71, o596-597.
57. A Stierle, D Stierle, T Girtsman, T.C. Mou, C Antczak, H Djaballah 2015 Azaphilones from an Acid Mine Waste Extremophilic Isolate of Pleurostomophora sp., manuscript in press, J Nat Prod
58. A Stierle, D Stierle 2015 Bioactive secondary metabolites produced by the fungal endophytes of conifers. Nat Prod Commun, 10(10): 1671-1682
59. A Stierle, D Stierle, D Decato 2015 The berkeleylactones, new antibiotic macrolides from a Berkeley Pit fungal co-culture, manuscript in preparation, J Nat Prod
60. A Stierle, D Stierle 2017 Secondary Metabolites of Acid Mine Waste Fungi. In "Topics in Biodiversity and Conservation", D Hawksworth, RRM Patterson (Eds), Springer, pp 213-244.