Homepage of Lone Gram

Pls note that this web-page is no longer being up-dated. Refer to http://www.aqua.dtu.dk/english/cv/ff/lone_gram/cv.aspx

Education and employment

Professor in fish microbial ecology since 2000 at the Department of Seafood Research, Danish Institute for Fisheries Research. From 2005, in a collaborative professorhip with Center for Biomedical Microbiology, BioCentrum, at the Technical University of Denmark. Trained as food scientist 1980-1985 with a Ph.D. degree from the Royal Veterinary and Agricultural University (RVAU) in food microbiology in 1989. Visiting research scientist in 1994-1995 and in 1999 at Professor Staffan Kjelleberg's group at University of New South Wales, Sydney, Australia. External associate professor at the RVAU since 1989. Several consultancies for the Food and Agricultural Organization of the United Nations working on projects and courses related to fish technology. Member (since 1998) and secretary (since 2003) of ICMSF; the International Commission on Microbiological Specifications for Foods  (revised March 2007).

Denmark has launched a marine scientific cruise (Galathea3) where a project headed by LG is on board the whole cruise.  The purpose of the project is to collect marine bacteria and filamentous fungi with effects against other microorganisms or mammalian cells.

        I have joined the cruise from Copenhagen to Greenland, around Australia, to the Antarctic and again across the Atlantic. We have cultured bacteria from water (CTD cast; see right) and replica plated onto a marine Vibrio. Several marine organisms with antibacterial activity have been isolated.

 

Lecture notes and transparencies

Power point files of the lectures are found here: 

Course: Medical Microbiology 2007 (DTU 27258)

       Lecture 1 (15th February); file with 2 slides per page or 6 slides per page

Course: "Juni-kursus" 2005 at the Danish Institute for Fisheries Research

        Lecture on control of fish disease 

Course: Food microbiology for food science students at KVL (November 2005): 

        Lecture 1 on spoilage and Lecture 2 on pathogens

Course: Food preservation for food science students at KVL (February 2005):

        Lecture on biofilm

Course: "Januar-kursus" 2005 at the Danish Institute for Fisheries Research

       Lecture on pathogens in lightly preserved fish  and  Biopreservation

Course: "Hygiejnisk design af procesudstyr til fødevareproduktion" 2005 at BioCentrum, DTU

       Lecture on biofilm

Course: "Zoonoses" 2004 at Dept. Vet. Microbiology, Royal Vet. Agric. University

        Lecture on seafood products

Course: Fermented Food (13th February 2003)

        Lecture on fermented fish

 

Literature on fish microbiology can be found in

Gram, L. 2005. Fish and seafood products. In ICMSF 2005. Microorganisms in Foods 6: Microbial Ecology of Food Commodities. 2nd edition. ISBN: 0-306-48675-X. Available from Kluwer Academic  & Plenum Publishers,

Gram, L. and H.H. Huss 2000. Fresh and processed fish and shellfish. In Lund, B.M., A.C. Baird-Parker and G.W. Gould (eds) The Microbiological Safety and Quality of Foods. Aspen Publishing Inc. Maryland, USA. pp. 472-506. 

Huss, H.H. (ed) 1995. Quality and Quality Changes in Fresh Fish. FAO Fish. Techn. Pap. No. 348. 195 pp

Huss, H.H., L. Ababouch, L. Gram 2003. Assessment and management of seafood safety and quality. FAO Techn. Pap. no. 444, p. 229. 

   ftp://ftp.fao.org/docrep/fao/006/y4743e/y4743e00.pdf  (Chapters 1-5)

   ftp://ftp.fao.org/docrep/fao/006/y4743e/y4743e01.pdf  (Chapter 6)

   ftp://ftp.fao.org/docrep/fao/006/y4743e/y4743e02.pdf  (Chapters 7-15)

   ftp://ftp.fao.org/docrep/fao/006/y4743e/y4743e03.pdf  (Index)

 

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Research areas

My group studies the microbial ecology of fish and fish products (Gram 2005, Gram and Huss 2000). This includes studies of bacteria such as Shewanella putrefaciens, fluorescent pseudomonads or Listeria monocytogenes important for spoilage and safety of seafood products, respectively. Also, we are interested in aquacultured fish species; in particular non-antibiotic based disease control methods such as probiotics or blocking of bacteria quorum sensing. Potential fish probiotics include Roseobacter and Pseudomonas species. Methods range from traditional culturing, phenotypic characterization to typing by RAPD and antibody and probe detection. Several of our current research projects deal with various aspects of interactions between bacteria and between bacteria and the eucaryotic host .

In 2006, we have joined a major scientific marin cruise (Galathea3) where we will determine the distribution of bacteria with antibacterial activity in the marine environment around the globe. Specifically, we will search for organisms belonging to the Roseobacter clade This work can potentially be of interest in drug discovery work. A short Danish description of the project is available.

 

Novel antibacterial compounds

 

We have a constant need for controlling unwanted bacteria - be it infectious or spoiling organisms. We spend a vast amount of our time removing or killing bacteria; washing, cleaning, disinfecting, in food preservation - and for treatment of infectious diseases. We have worked with a multitude of novel antibacterial compounds - bacteriocins, antimicrobial peptides, enzymes and compounds affecting quorum sensing.

 
Hansen, E.H., T. Schæfer, S. Molin and L. Gram 2005. Effect of environmental and physiological factors on the antibacterial activity of Curvularia haloperoxidase system. J. Appl. Microbiol. 98, 581-588 Nilsson, L., M.K. Nielsen, Y. Ng and L. Gram 2002. Role of acetate in production of an autoinducible class IIa bacteriocin in Carnobacterium piscicola A9b. Appl. Environ. Microbiol. 68:2251-2260

 

Fish probiotics and interactions between marine bacteria

 
An ever increasing amount of fish is being produced in aquaculture - today almost 40% of fish used for human consumption are farmed. Although vaccines have been tremendously succesful as disease control measures, antibiotics are still used against several bacterial fish diseases. Due to the concerns raised vis-a-vis development of antibiotic resistance, alternative disease control measures must be sought . Probiotics (live microbial cultures which when supplied to the host confers a beneficial effect) have, in some scenarios, been succesful. We are currently especially interested in the potential of marine Roseobacter as fish larval probiotics. We collaborate with German and US based groups on this organism

 

Bruhn, J.B., J. Haagensen, D. Bagge-Ravn and L. Gram 2006. Culture conditions of Roseobacter strain 27-4 affect its attachment and biofilm formation quantified by real time PCR. Appl. Environ. Microbiol. 72, 3011-3015

 

Bruhn, J.B., K.F. Nielsen, M. Hjelm, M. Hansen, J. Bresciani, S. Schultz and L. Gram 2005. Ecology, inhibitory activity and morphogenesis of a potential marine fish larvae probiotic bacteria, Roseobacter strain 27-4. Appl. Environ. Microbiol. 71, 7263-7270

 

Bruhn, J.B., L. Gram and R. Belas 2007. Production of antibacterial compound and biofilm formation in dinoflagellate associated Roseobacter species are influenced by culture conditions. Appl. Environ. Microbiol. 73: 442-450

 

Gram, L.,  J. Melchiorsen, B. Spanggard, I. Huber and T. F. Nielsen 1999. Inhibition of Vibrio anguillarum by Pseudomonas flourscens strain AH2- a possible probiotic treatment of fish. 1999. Appl. Environ. Microbiol. 65 969-973

 

Hjelm, M., Ø. Bergh, J. Nielsen,  J. Melchiorsen, S. Jensen, H. Duncan, A. Riaza, P. Ahrens, H. Birkbeck and L. Gram  2004. Selection and identification of  autochthonous Selection and identification of  autochthonous potential probiotic bacteria from turbot larvae (Scophtalmus maximus) rearing units. Syst. Appl. Microbiol. 27, 360-371

 

Hjelm, M., A. Riaza, F. Formosa J. Melchiorsen and L. Gram 2004. Seasonal incidence of autochtonous antagonistic  bacteria, Roseobacter spp. and Vibrionaceae, in a turbot larvae (Scophthalmus maximus) rearing system. Appl. Environ. Microbiol. 70, 7288-7298

 

Huber, I., B. Spanggaard, J. Nielsen, K.F. Appel, T.F. Nielsen and L. Gram 2004. Phylogenetic analysis and in situ identification of the intestinal microbial community of rainbow trout (Onchorhynchus mykiss, Walbaum). J. Appl. Microbiol. 96, 117-132

 

Planas, M., M. Pérez-Lorenzo, M. Hjelm, L. Gram, I. Uglenes Fiksdal, Ø. Bergh and J. Pintado 2006. Probiotic effect in vivo of Roseobacter strain 27-4 against Vibrio anguillarum infections in turbot (Scophthalmus maximus L.) larvae. Aquaculture 255, 323-333

 

Spanggaard, B., I. Huber, J. Nielsen, E.B. Sick, C. B. Pipper, T. Martinussen, W.J. Slierendrecht and L. Gram 2001. The probiotic potential against vibriosis of the indigenous microflora of rainbow trout. Env. Microbiol. 3, 755-765

 

Quorum related interactions between bacteria on fish and in fish products

 

Bacteria will through antagonistic and synergistic activity interact and influence the growth and metabolism of one another.   Many pathogenic bacteria and symbiotic bacteria employ acylated homoserine lactones (AHLs) in cell-to-cell communication. This communication enables them to coordinate gene expression, e.g. toxin production, in a population. We have assessed the importance of AHL communication in food spoilage and are currently working on model systems allowing us to evaluate the effect of specific quorum sensing inhibtiors. We also study AHL-signalling in fish pathogenic bacteria and have recently demonstrated that compounds interfereing with AHL-systems (so-called quorum sensing inhibtors) dramatically reduce vibriosis mortality in rainbow trout . Studies on AHL signalling and QSI compounds are carried out in close collaboration with Professor Michael Givskov and Dr. Thomas Ostenfeld at BioCentrum at the Technical University of Denmark. We also collaborate with Dr. Kristian F. Nielsen at Neurosearch A/S.

 

Bruhn, J.B., A.B. Christensen, L.R. Flodgaard, K.F. Nielsen, T.O. Larsen, M. Givskov and L. Gram 2004. Presence of acylated homoserine lactones (AHLs) and AHL producing bacteria in meat and potential role of AHL in spoilage of meat. Appl. Environ. Microbiol. 70:4293-4302

Bruhn, J.B., I. Dalsgaard, K.F. Nielsen, C. Buchholtz,  J.L. Larsen and L. Gram 2005. Demonstration of quorum sensing signal molecules (acylated homoserine lactones) in Gram-negative fish pathogenic bacteria. Dis. Aquat.Org. 65, 43-52.

Buch, C.,  J. Sigh, J. Nielsen, J.L. Larsen, and L. Gram 2003. Production of acylated homoserine lactones by different serotypes of Vibrio anguillarum both in culture and during infection of rainbow trout. Syst. Appl. Microbiol. 26:338-349

Buchholtz, C., K.F. Nielsen, D. Milton, J.L. Larsen and L. Gram 2006. Profiling of acylated homoserine lactones of Vibrio anguillarum in vitro and in vivo: influence of growth conditions and serotype. Syst. Appl. Microbiol. 29:433-445

Flodgaard, L.R., P. Dalgaard,  J.B. Andersen, K.F. Nielsen, M. Givskov and L. Gram 2005. Non-bioluminescent strains of Photobacterium phosphoreum produce the cell-to-cell communication signal 3-hydroxyl-octanoyl homoserine lactone. Appl. Environ. Microbiol. 71:2113-2120

Gram, L., L. Ravn, M. Rasch, J. B. Bruhn, A.B. Christensen and M. Givskov 2002. Food spoilage – interactions between food spoilage bacteria. Int. J. Food Microbiol. 78:79-97

 

Kastbjerg, V.G., K.F. Nielsen, I Dalsgaard, M. Rasch, J.B. Bruhn, M. Givskov and L. Gram 2007. Profiling acylated homoserine lactones in Yersinia ruckeri and influence of exogenous acyl homoserine lactones and known quorum sensing inhibitors on protease prodution. J. Appl. Microbiol. (in press).

Ravn, L., A.B. Christensen, S. Molin, M. Givskov and L. Gram 2001. Methods for identifying and quantifying acylated homoserine lactones produced by Gram-negative bacteria and their application in studies of AHL-production kinetics. J. Microbiol. Methods 44:239-251

Rasch, M., C. Buch, B. Austin, W. Sliehendrecht, J.L. Larsen, M. Givskov and L. Gram. 2003. An inhibitor of bacterial quorum sensing reduces mortalities caused by vibriosis in rainbow trout (Oncorhynchus mykiss, Walbaum). System. Appl. Microbiol. 27:350-359

Rasch, M., J.B. Andersen, K.F. Nielsen, L. R. Flodgaard, H. Christensen, M. Givskov and L. Gram 2005. Involvement of bacterial quorum sensing signals in spoilage of bean sprouts. Appl. Environ. Microbiol. 71, 3321-3330.

Rasch, M., V.G. Kastbjerg, I. Dalsgaard, J.B. Bruhn, M. Givskov and L. Gram 2006. Production of acylated homoserine lactones by Aeromonas salmonicida and inhibitory effect of quorum sensing inhibitors on protease production. Dis. Aquat. Org. (accepted)
   

 

Ecology and detection of Shewanella putrefaciens

 

The spoilage of aerobically stored iced fish is mainly caused by growth and metabolism of S. putrefaciens. We have used the spoilage reactions (e.g. reduction of trimethylamine oxide and production of H2S or antibody technology for specific detection of this organism. S. putrefaciens is able to use many compounds, including Fe3+, as electron acceptors. We have shown that during aerobic respiration, S. putrefaciens uses specific iron chelators, so-called siderophores, for iron uptake  and that fish based substrates are well suited for detection of siderophore production by several bacteria.

Recently we have shown that many mesophilic strains formerly identified as S. putrefaciens belong to a different species, Shewanella algae which may cause wound infections and bacteremia in humans. S. algae is a marine bacterium and can be detected in Danish marine waters when the water temperature is above 15°C.

 

Fonnesbech Vogel, B., K. Jørgensen, H. Christensen, J. E. Olsen and L. Gram 1997. Differentiation of Shewanella putrefaciens and Shewanella alga using ribotyping, whole-cell protein profiles, phenotypic characterization and 16S rRNA sequence analysis. Appl. Environ. Microbiol. 63, 2189-2199

 

Fonnesbech Vogel, B., K. Venkateswaran, M. Satomi, and L. Gram 2005. Identification of Shewanella baltica as the most important H2S-producing species during iced storage of Danish marine fish. Appl. Environ. Microbiol. 11, 6689-6697

 

Gram, L. 1992. Evaluation of the bacteriological quality of seafood. Int. J. Food Microbiol. 16, 25-39

 

Gram, L. 1994. Siderophore-mediated iron sequestering by Shewanella putrefaciens. Appl. Environ. Microbiol. 60, 2132-2136

 

Gram, L. 1996. The influence of substrate on siderophore production by fish spoilage bacteria. J. Microbiol. Meth. 25, 199-205

 

Gram, L., B. Fonnesbech Vogel, A. Bundvad, J. Melchiorsen and C. Johansen. Occurrence and survival of Shewanella algae in marine waters depending on water temperature and mode of growth. Appl. Environ. Microbiol. 65, 3896-3900

 

Satomi, M., B.F. Vogel, L. Gram and K. Venkateswaran 2006. Description of two Shewanella species, Shewanella hafniensis sp. nov., and Shewanella morhaue sp. nov., isolated from the marine fish of the Baltic Sea, Denmark. Int. J. System. Evol. Microbiol. 56, 243-249.

 

Hygiene and biofilms

 

In the environment most bacteria will grow adhered to surfaces and not as free living cells. The ability to grow at surfaces as biofilms is also important in food processing environments. We have studied the biofilm formation and the subsequent enzymatic removal of biofilms by several methods . These studies are continued in collaboration with several Danish research institutes and industries in which we study the adherence of Listeria monocytogenes and Shewanella putrefaciens to surfaces used in the food industry. We have, in model systems  evaluated different surface modifications and have determined the effect of surface roughness (of stainless steel) on bacterial adhesion. On an industrial scale, we have compared different types of disinfection processes with respect to effect on hygienic level in general, on on Listeria monocytogenes. We are currently investigating how surface coatings (e.g. fish extracts) can be used to reduce bacterial adhesion withing interfering with growth of the bacterial cell. We collaborate with several Danish and international research groups and participate in the PathogenCombat integrated research project.

 

Bagge, D., C. Johansen, I. Huber, M. Hjelm and L. Gram 2001. Adhesion and biofilm formation of Shewanella putrefaciens on food processing surfaces. Appl. Environ. Microbiol. 67, 2319-2325.

 

Bagge-Ravn, D., K. Gardshodn, L. Gram and B. Fonnesbech Vogel 2003. Comparison of sodium hypochlorite-based foam and peroxyacetic acid-based fog sanitizing procedures in a salmon smokehouse: survival of the general microflora and Listeria monocytogenes. J. Food Prot. 66, 592-598

 

Gram, L., Bagge-Ravn, D., Y. Ng, P. Gymoese, and B. Fonnesbech Vogel 2007. Influence of food soiling matrix on cleaning and disinfection efficiency on surface attached Listeria monocytogenes. Food Control (in press)

 

Hansen, E.H., L. Albertsen, C. Johansen, T. Schæfer, J. Frisvad, S. Molin and L. Gram 2003. Curvularia haloperoxidase: antimicrobial activity and potential application as a  surface disinfection. Appl. Environ. Microbiol.  69, 4611-4617

 

 

Hansen, E.H., M.A. Schembri, P. Klemm, T. Schäfer, S. Molin and L. Gram 2004. Elucidation of the antibacterial mechanism of the Curvularia haloperoxidase system using DNA micro-array profiling. Appl. Environ. Microbiol. 70, 1749-1757

 

Hilbert, L.R., D. Bagge-Ravn, J. Kold and L. Gram 2003. Influence of surface roughness of stainless steel on microbial adhesion and corrosion. Int. J. Biodet. Biodegr. 52, 175-185

 

Johansen, C., P. Falholt and L. Gram 1997. Enzymatic removal and inactivation of bacterial biofilms. Appl. Environ. Microbiol. 63, 3724-3728

 

Kingshott, P., J. Wei, D. Bagge-Ravn, N. Gadegaard and L. Gram 2003. Covalent attachment of poly(ethylene glycol) to surfaces is critical for preventing bacterial adhesion. Langmuir 19, 6912-6921

 

Wei, J., D. Bagge-Ravn, L. Gram and P. Kingshott 2003. Stainless steel modified with poly(ethylene glycol) can prevent protein adsorption but not bacterial adhesion. Colloids and Surfaces B:Biointeractions 32, 275-291

 

       

Listeria monocytogenes - ecology and virulence

 
Listeria monocytogenes is an important food-borne pathogen that, in high risk population groups, can cause the serious infectious disease, listeriosis. The disease is typically transmitted with ready-to-eat food products in which the organism can grow to high numbers. We study all aspects related to measures than can control the organism. This includes its prevalence in the environment, its persistance in food processing, its biofilm formation, prevention of growth using bioprotection - and recently also its interaction with eucaryotic cells and hosts. We have projects both at the very applied level - working with the fish processing industry - and at a more basic scientific level where we collaborate with several Danish research groups.

 

Alves, V.F., E.C.P. de Martinis, M.T. Destro, B. Fonnesbech Vogel and L. Gram 2005. Antilisterial activity of a Carnobacterium piscicola isolated from Brazilian smoked fish [Surubim (Platystoma sp.)] and its activity against a persistent Listeria monocytogenes isolated from surubim. J. Food Prot. 68, 2068-2077

 

Bruhn, J.B., B. Fonnesbech Vogel and L. Gram 2005. Bias in the enrichment procedure for Listeria monocytogenes: lineage 2 strains outcompete lineage 1 strains in University of Vermont Broth. Appl. Environ. Microbiol. 71, 961-967.

 

Fonnesbech Vogel, B., B. Ojeniyi, P. Ahrens, L. Due Skov, H.H. Huss and L. Gram 2001. Elucidation of Listeria monocytogenes contamination routes in cold-smoked salmon processing plants detected by DNA-based typing methods. Appl. Environ. Microbiol. 67, 2586-2595

 

Hansen, C.H., B.F. Vogel and L. Gram 2006. Prevalence and survival of Listeria monocytogenes in Danish aquaculture and fish processing environments. J. Food Prot. 69, 2113-2122

 

Jensen, A., M.H. Larsen, H. Ingmer, B.F. Vogel and L. Gram 2007. Sodium chloride enhances adherence and aggregation and strain variation influences invasiveness of Listeria monocytogenes strains. J. Food Prot. (in press)

 

Martinez, I., L.-M. Rørvik, M. Seppola, V. Brox, J. Lassen, L. Gram and B.  Fonnesbech Vogel  2003. Genetic variability among isolates of Listeria monocytogenes from food products, clinical samples and processing environments, estimated by RAPD-typing. Int. J. Food Microbiol. 84, 285-297

 

Nilsson, L., T. Beck Hansen, P. Garrido, C. Buchrieser, P. Glaser, S. Knøchel, L. Gram and A. Gravesen 2005. Growth inhibition of Listeria monocytogenes by a nonbacteriocinogenic Carnobacterium piscicola. J. Appl. Microbiol. 98, 172-183.

 

Nilsson, L., Y. Ng, J.N. Christiansen, D. Jacobsen, B.L. Jørgensen and L. Gram 2004. The importance of a plasmid-encoded class IIa bacteriocin for inhibition of Listeria monocytogenes by Carnobacterium piscicola strain A9b. J. Appl. Microbiol. 96, 133-143.

 

Vogel, B.F., Y.Y.Ng, G. Hyldig, M. Mohr, O. Mejlholm and L. Gram 2006. Potassium lactate combined with sodium diacetate can inhibit growth of Listeria monocytogenes in vacuum-packed cold-smoked salmon and has no adverse sensory effects. J. Food Prot. 69:2134-2142

 

Wulff, G., L. Gram, P. Ahrens and B. F. Vogel 2006. Contamination patterns and persistance of Listeria monocytogenes in fish slaughter and smoke houses. Appl. Environ. Microbio. 72, 4313-4322

 
   

Other topics

bulletMy private time is shared with Peter Sestoft who has a nice photo of our summer cottage on his home page.