Adhesion of Zearalenone to the Surface of Lactic Acid Bacteria Cells

Zearalenone is mycotoxin harmful to the health of humans and animals and is present in food and feed. Therefore, last few decades, great attention is paid to the development of biological detoxification methods with reference to the application of lactic acid bacteria in binding and removal of mycotoxins from food and feed. The aim of this work was to investigate the ability of lactic acid bacteria Lactobacillus rhamnosus GG (ATCC 53103) and Lactobacillus plantarum A1 to bind zearalenone unto the cell surface. The results showed that Lactobacillus rhamnosus GG (ATCC 53103) and Lactobacillus plantarum A1 can bind signifi cant concentration of zearalenone, depending on the bacteria concentration in the medium and the incubation time. However, with longer time of incubation part of bounded mycotoxins were released back into the medium which indicates that the reaction of adhesion of toxin to the bacterial cells is reversible. Determination of zearalenone concentration was performed by competitive ELISA test

Listeria monocytogenes and other contaminants in fresh cheese and cream from Zagreb city area domestic production

Svrha ovog rada bila je odrediti udovoljavaju li svježi sir i vrhnje koji se proizvode na tradicionalan način u kućanstvu i slobodno prodaju na zagrebačkim tržnicama mikrobiološkim standardima za namirnice (NN 46/94, 20/01, 40/01). Posebna pažnja posvećena je istraživanju prisutnosti bakterije Listeria monocytogenes u navedenim namirnicama, zbog njezine izrazite opasnosti po ljudsko zdravlje. Od ukupno 120 istraživanih uzoraka mliječnih proizvoda, većina - 64 (53 %) bila je kontaminirana patogenim mikroorganizmima, od čega 16 % otpada na svježi sir a 37 % na uzorke vrhnja. Čak 39 uzoraka sira i 50 uzoraka vrhnja nije udovoljilo uvjetima propisanim pravilnikom, primarno zbog kontaminacije kvascima i plijesnima. Od 10 uzoraka sira i vrhnja u kojima je dokazana L. monocytogenes klasičnim mikrobiološkim metodama, PCR-metodom u samo jednom uzorku potvrđena je L. monocytogenes, i to uzorku vrhnja.The purpose of this research was to determine whether the cream cheese and cream that are produced in the traditional manner at home and are free to sale on Zagreb markets, meet microbiological requirements for foodstuffs (OG 46/94, 20/01, 40/01). Particular attention is given to research of bacteria Listeria monocytogenes presence in these foods, because of its exceptional hazards to human health. It was found that a majority of 64 (53 %) from a total of 120 studied dairy products samples were contaminated with microbial pathogens, of which 16 % are waste in the cream cheese, and 37 % in cream samples. 39 samples of cheese and 50 samples of cream did not fulfil the conditions prescribed by the Croatian Guidelines, primarily due to the contamination with yeasts and moulds. In 10 cheese and cream samples where L. monocytogenes is proven by classical microbiological methods, PCR method confirmed L. monocytogenes in only one cream sample

Characterization of bacterial strain Lactobacillus plantarum 1K isolated from Slavonian “kulen“, as probiotic functional starter culture

U ovom je radu ispitana adhezija bakterijskoj soja L. plantarum 1K izoliranog iz kulena na tanko i debelo crijevo miša u in vitro i in vivo uvjetima. Budući da je u preliminarnim istraživanjima L. plantarum 1K pokazao značajnu inhibiciju rasta prema patogenim mikroor- ganizmima iz hrane, proizveo značajnu količinu mliječne kiseline (21,96 g/l) te zadovoljio osnovne kriterije za selekciju probiotičkog soja u in vitro uvjetima, provedena su in vivo istraživanja na pokusnim miševima. L. plantarum 1K znatno smanjuje broj bakterijskih stanica Salmonella sp. u miševa inciranih sa bakterijom Salmonella sp., te smanjuje translokaciju Salmonella sp. u jetru miševa. L. plantarum 1K je pokazao osnovne funkcionalne kriterije za izbor probiotičkih sojeva, te se kao takav može upotrijebiti kao funkcio- nalna autohtona starter kultura za fermentirane mesne proizvode.The aim of this work was to investigate adhesion ability of bacterial strain L. plantarum 1K, isolated from Slavonian “kulen”, on small and large intestine of mice in vitro and in vivo conditions. Considering that in preliminary investigation L. plantarum 1K has shown good antimicrobial activity against pathogen microorganisms from food, it has produced signicant amount of lactic acid (21,96 g/l) and satised the basic criteria for selection of probiotic strains in in vitro conditions, in vivo studies in experimental mice were carried out. L. plantarum 1K signicantly reduced the number of bacterial cells of Salmonella sp. in mice infected with bacterium Salmonella sp. and reduced the translocation of bacteria Salmonella sp. in the liver of mice. Considering that L. plantarum 1K has demonstrated the basic functional criteria for the selection of probiotic strains, so as such, it can be used as functional autochthonous starter culture for fermented meat products

Antifungal Effect of the Bacterium Lactobacillus plantarum K1 on Growth of Mold Aspergillus ochraceus ZMPBF 318

Većina namirnica i krmiva osjetljiva je na kontaminaciju plijesnima u različitim fazama proizvodnje, prerade, transporta i uskladištenja. Tako klimatski uvjeti i uvjeti prilikom procesa proizvodnje, transporta i uskladištenja mogu pospješiti porast plijesni, kao i sintezu mikotoksina. Suvremena proizvodnja zahtijeva što manju upotrebu kemijskih spojeva za očuvanje i zaštitu prehrambenih proizvoda i krmiva pa se koriste bakterije mliječne kiseline koje proizvode metabolite koji imaju antifungalni učinak, te sprečavaju kvarenje hrane i krmiva uzrokovano nepoželjnim vrstama plijesni. Stoga je u ovom radu istraživano antifungalno djelovanje izolata bakterije mliječne kiseline Lactobacillus plantarum K1 na rast plijesni Aspergillus ochraceus ZMPBF 318 u tekućoj hranjivoj podlozi (kvaščev ekstrakt) pri 28 °C tijekom 28 dana. Istraživanja rasta ove plijesni su provedena u podlozi uz dodatak supernatanta fermentirane hranjive podloge u kojoj je porasla bakterija Lactobacillus plantarum K1 i u prisutnosti suspenzije stanica ove bakterije. Rezultati su pokazali da suspenzija stanica bakterije Lactobacillus plantarum K1 značajno inhibira rast plijesni tijekom prvih 14 dana inkubacije, dok supernatant pokazuje dobar inhibitorni utjecaj na rast plijesni kroz duži period inkubacije.Most of the food and feed are contamination sensitive to molds in various stages of production, processing, transportation and storage. Thus, climate conditions and conditions during the production process, transport and storage can enhance the growth of molds and mycotoxin synthesis. Reduced utilization of chemical compounds added in order to preserve and protect food and animal feed is required in modern production. So, lactic acid bacteria which produce metabolites with antifungal effect and prevent spoilage of food and feed by undesirable molds have been used. Therefore, in this paper antifungal activity of isolate of lactic acid bacterium Lactobacillus plantarum K1 on the growth of mold Aspergillus ochraceus ZMPBF 318 in broth (yeast extract) at 28 °C for 28 days was investigated. Investigation of the growth of the mold was carried out in the broth with addition of supernatant of fermented broth in which bacterium Lactobacillus plantarum K1 grew and in the presence of the bacterial cell suspension. The results show that during fi rst 14 days of incubation the mold growth was significantly inhibited by cell suspension of bacterium Lactobacillus plantarum K1, while good inhibitory effect of the supernatant on the growth of the mold was obtained with longer incubation time

Aflatoxin M1 in raw milk and binding of aflatoxin by lactic acid bacteria

Aflatoksin M1 (AFM1) potencijalni je karcinogen za ljude, te njegova prisutnost u mlijeku i mliječnim proizvodima predstavlja opasnost za ljudsko zdravlje. Stoga se u ovom radu određivao stupanj mikrobiološkog onečišćenja plijesnima te potencijalna prisutnost aflatoksina M1 u 60 uzoraka sirovog mlijeka, nasumično uzetih od individualnih proizvođača iz različitih krajeva kontinentalne Hrvatske. Najčešće izolirani rodovi plijesni bili su Geotrichum (78,3 %), Aspergillus (32,4 %) i Penicillium (27,0 %). Od ukupno 60 istraživanih uzoraka mlijeka u 86,66 % utvrđena je prisutnost aflatoksina M1, a u 6,66 % uzoraka količine su bile iznad dozvoljenih granica. Bakterije mliječne kiseline koje se koriste u proizvodnji fermentiranih mliječnih proizvoda kao starter kulture, mogu imati ulogu u smanjenju količine aflatoksina u hrani i krmivu. U ovom je radu istražena i sposobnost bakterija mliječne kiseline Lactobacillus rhamnosus GG (ATCC 53103), Lactobacillus delbrueckii S1 i Lactobacillus plantarum A1 da vežu aflatoksin M1. Standardni soj L. rhamnosus GG (ATCC 53103) i izolat L. delbrueckii S1 mogu značajno (P50%) u usporedbi s izolatom L. plantarum A1 koji ga može vezati između 18,7 do 28,7 %.Aflatoxin M1 (AFM1) is potential human carcinogen. Its presence in milk and dairy products represents risk for human health. Therefore, this study was carried out in order to determine thedegree of microbiological contamination by mold, and the potential presence of aflatoxin M1 in 60 raw milk samples, randomly taken from individual producers from different regions of the continental Croatia. The most common genera isolated fungi were Geotrichum (78.3 %), Aspergillus (32.4 %) and Penicillium (27.0 %). From total of 60 studied milk samples, 86.66 % were positive for the presence of aflatoxin M1, and 6.66 % of samples were above the prescribed limits. Lactic acid bacteria used in fermented dairy products as a starter culture may play a role in reduction of aflatoxin in foods and nutrients. In this paper the ability of lactic acid bacteria: Lactobacillus rhamnosus GG (ATCC 53103), Lactobacillus delbrueckii S1 and Lactobacillus plantarum A1 to bind aflatoxin M1 was investigated. Standard strain L. rhamnosus GG (ATCC 53103) and L. delbrueckii S1 can significantly (P50 %) compared to L. plantarum A1, which binds AFM1 between 18.7 to 28.7 %

Microbial Communities and Biofilms

Sve do godine 1960. mnoga stajališta okolišne mikrobiologije bila su postupci na osnovi promatranja. U novije doba bilo je izvrsnih prosudbi za razumijevanje ekonomski važnih neobičnih pojava, poput simbiotskih odnosa između bakterija iz roda Rhizobium i leguminoznih biljaka, dok je osnova bila temeljno razumijevanje odnosa između mikrobnoga rasta i fizičkih parametara, poput temperature i različitih tipova međudjelovanja između različitih mikroba u danome okolišu. Sveukupno, međutim, velik broj opažanja ostao je slabo objašnjen i po mnoge mikrobiologe činilo se da su različiti primjeri upotrijebljeni radi objašnjenja i interpretacije ponašanja mikroba u prirodnome okolišu bili manjkavi. U protekla tri desetljeća situacija se bitno promijenila i svo vrijeme, na sreću okolišnih mikrobiologa, mnogi slabo razumljivi zaostaci, sada ponovo egzistiraju kao poredak razumljiv koji je iznimno proširio razumijevanje odnosa između mikroba i njihova okoliša. Dva primjera za to jesu razumijevanje tvorbe biofilma i njegova okolišna važnost i strategija preživljavanja mikroba koji ne tvore endospore.Until the 1960s many aspects of environmental microbiology were dealt with on an observational basis. Certainly there was a good measure of understanding of economically important phenomena, such as the symbiotic relationship between Rhizobium and leguminous plants, while there was a basic understanding of the relationship between microbial growth and physical parameters, such as temperature and of the various types of interaction between different microorganisms in the same environment. Overall, however, many observations remained poorly explained and, to many microbiologists, it appeared that the various paradigms used to explain and interpret the behaviour of microorganisms in natural environments were defi cient. Over the past two decades, the situation has changed and while, happily for environmental microbiologists, much remains less than fully understood, there now exists a framework of knowledge which has greatly expanded the understanding of the relationship between microorganisms and their environments. Two examples are an understanding of biofi lm formation and its environmental importance and of the survival strategies of non-endospore forming microorganisms

The Effect of Experimental Fungal Emulation on Colonization of Soybeans by Moulds of the Genus Aspergillus and Fusarium and on Aflatoxin B1 Accumulation in Relation to Temperature and Moisture Content in vitro

One strain of Aspergillus flavus ATCC 26949 and one strain of Fusarium graminearum ZMPBF 1244 were used to investigate the effect of growth in mixed culture on aflatoxin B1 (AFB1) accumulation in respect to time and temperature of cultivation in vitro. The experiments were carried out with aflatoxigenous mould A. flavus ATCC 26949 in pure culture and in mixed culture, respectively, the latter with the common mould F. graminearum ZMPBF 1244. F. graminearum does not produce aflatoxins and chromatographycally similar compounds. The amount of biomass was estimated by measuring the chitin content; the aflatoxin accumulation by means of UV light and ELISA method. It was established that the accumulation of AFB1 primarily depend on the temperature of cultivation, rather than on growth of the mycelium. The biomass of the mixed culture of A. flavus and F. graminearum after 35 days of cultivation reduces the amount of AFB1 by 55 to 76% in respect to highest values obtained in experiments with the pure culture of A. flavus. Decrease of this toxin amount is more pronounced in the substrate at the higher water content and at the higher temperature of cultivation. As a general rule, cultures grown in mixed culture under investigate temperature conditions produced less amount of AFB1 than A. flavus grown in pure culture

Dominant microflora of fermented horse meat sausages

Budući da se proizvodi od konjskog mesa, u našoj zemlji, proizvode u malim domaćinstvima na tradicionalan način, a konačan pro- izvod ovisi o prisutnosti i aktivnosti prirodne mikroore, svrha ovog rada bila je odrediti mikrobnu populaciju i kemijske parametre u fermentiranim kobasicama od konjskog mesa, te izolirati i karakterizirati prisutne autohtone starter kulture i istražiti njihovu spo- sobnost inhibicije rasta patogenih bakterija. U uzorku kobasice od konjskog mesa biokemijskim API testovima dokazane su bakterija Serratia odorifera iz obitelji Enterobacteriaceae, Staphylococcus aureus, bakterija Listeria grayi, bakterije iz roda Salmonella i sul- toreducirajuće klostridije nisu utvrđene, a dokazan je i kvasac – Candida zeylanoides. Dominantna mikroflora u uzorku kobasice bio je izolat bakterija mliječne kiseline Lactococcus lactis ssp. lactis 5K1 u broju 8,301 log10cfu g-1. Na MRS podlozi (selektivnoj podlozi za bakterije mliječne kiseline) L. lactis ssp. lactis 5K1 proizveo je 13,83gL-1 mliječne kiseline (HPLC), te zakiselio podlogu na 4,16 pH vrijednost i pokazao znatno antimikrobno djelovanje prema patogenim test mikroorganizmima. U radu su praćeni i kemijski para- metri: udio vode (41,12%), masti (20,93%), proteina (27,29%), natrijevog klorida (3,78%), pH (4,94) i sadržaj nitrita (0,983 mgkg-1).Since the products of horse meat in our country, produced in small households in the traditional way, and the nal product depends on the presence and activity of natural microora, the purpose of this study was to determine the microbial population and chemical parameters in dry fermented sausages of horse meat, and isolate and characterize the presence of autochthonous starter cultures and to investigate their ability to inhibit growth of pathogenic bacteria. In the samples of horse meat sausages were detected bacteria Seratia odorifera from the family Enterobacteriaceae, Staphylococcus aureus, API Listeria test conrmed the bacteria L. grayi, bacteria of the genus Salmonella and Sulphite reducing clostridia not established, and detected yeast - Candida zeylanoides. The dominant microora in the samples of sausages were lactic acid bacteria Lactococcus lactis ssp. lactis 5K1 in the number log10cfu 8.301 g-1. On the MRS medium (selective medium for lactic acid) Lactococcus lactis ssp. lactis 5K1 produced 13,83gL-1 of lactic acid (HPLC) and acidify media at pH value of 4.16 and showed significant antimicrobial activity against pathogenic test microorganisms. In the paper were also observed chemical parameters: water content (41,12%), fat (20,93%), protein (27,29%), sodium chloride (3,78%), pH (4,94) and nitrite content (0,983 mgkg-1)

Biorazgradnja otpadne vode iz procesa proizvodnje maslinova ulja s pomoću Trichosporon cutaneum i Geotrichum candidum

Olive oil production generates large volumes of wastewater. These wastewaters are characterised by high chemical oxygen demand (COD), high content of microbial growth-inhibiting compounds such as phenolic compounds and tannins, and dark colour. The aim of this study was to investigate biodegradation of olive mill wastewater (OMW) by yeasts Trichosporon cutaneum and Geotrichum candidum. The yeast Trichosporon cutaneum was used because it has a high potential to biodegrade phenolic compounds and a wide range of toxic compounds. The yeast Geotrichum candidum was used to see how successful it is in biodegrading compounds that give the dark colour to the wastewater. Under aerobic conditions, Trichosporon cutaneum removed 88 % of COD and 64 % of phenolic compounds, while the dark colour remained. Geotrichum candidum grown in static conditions reduced COD and colour further by 77 % and 47 %, respectively. This investigation has shown that Trichosporon cutaneum under aerobic conditions and Geotrichum candidum under facultative anaerobic conditions could be used successfully in a two-step biodegradation process. Further investigation of OMW treatment by selected yeasts should contribute to better understanding of biodegradation and decolourisation and should include ecotoxicological evaluation of the treated OMW.Tijekom proizvodnje maslinova ulja nastaju velike količine otpadne vode. Karakterizira je visoka kemijska potrošnja kisika (KPK), visoka koncentracija sastojaka koji inhibiraju rast mikroorganizama, poput fenolnih spojeva i tanina i tamna boja. Cilj ovog rada je bio istražiti biorazgradnju otpadne vode iz procesa proizvodnje maslinova ulja s pomoću kvasaca Trichosporon cutaneum i Geotrichum candidum. Kvasac Trichosporon cutaneum u ovom je istraživanju uporabljen zbog svog visokog potencijala za biorazgradnju fenolnih i drugih toksičnih spojeva. Kvasac Geotrichum candidum uporabljen je kako bi se istražilo koliko je uspješan u biorazgradnji spojeva koji otpadnoj vodi daju tamnu boju. Pri aerobnim uvjetima Trichosporon cutaneum uklonio je 88 % KPK i 64 % fenolnih spojeva, dok tamna boja otpadne vode preostaje. Geotrichum candidum u statičkim je uvjetima smanjio KPK i boju za 77 %, odnosno 47 %. Ovo je istraživanje pokazalo da Trichosporon cutaneum pri aerobnim uvjetima i Geotrichum candidum pri fakultativno anaerobnim uvjetima mogu biti uspješno uporabljeni u dvostupanjskom procesu biorazgradnje. Daljnje istraživanje obrade otpadne vode iz procesa proizvodnje maslinova ulja s pomoću odabranih kvasaca trebalo bi pridonijeti boljem razumijevanju biorazgradnje i uklanjanju boje i trebalo bi biti provedeno zajedno sa ekotoksikološkim vrednovanjem obrađene otpadne vode