Access restricted to students and staff of home institution
master's thesis
Selekcija autohtonih sojeva Sinorhizobium meliloti otpornih na nepovoljne uvjete u okolišu

Anja Komes (2016)
Sveučilište u Zagrebu
Agronomski fakultet
Mikrobiologija
Metadata
TitleSelekcija autohtonih sojeva Sinorhizobium meliloti otpornih na nepovoljne uvjete u okolišu
AuthorAnja Komes
Mentor(s)Sanja Sikora (thesis advisor)
Abstract
Dušik je esencijalni element rasta i reprodukcije biljaka čiji nedostatak u tlu je često limitirajući faktor u biljnoj proizvodnji. Kako bi se nadoknadio nedostatak dušika nastoje se iskoristiti korisne asocijacije između kvržičnih bakterija (rizobija) i leguminoza. Simbiozna fiksacija dušika ima jedinstvenu ulogu u unosu dušika u tlo i predstavlja važnu komponentu u postizanju većih prinosa različitih leguminoznih usjeva. Stoga je važno izvršiti selekciju visoko učinkovitih sojeva kvržičnih bakterija na različite uvjete u tlu. Lucerna ( Medicago sativa L.) je vrlo značajna krmna kultura koja stvara simbiozne odnose sa kvržičnom bakterijom Sinorhizobum meliloti. Kako bi povećali prinose ove krmne kulture, preporučuje se bakterizacija lucerne sa visoko kvalitetnim sojevima kvržičnih bakterija. Cilj ovog istraživanja je izvršiti selekciju autohtonih sojeva S. meliloti s područja Istarske, Zadarske, Koprivničko-križevačke i Brodsko-posavske županije na nepovoljne uvjete vanjske sredine. Rast sojeva istraživan je na različitim koncentracijama NaCl-a, pH vrijednostima, temperaturama i izvorima ugljikohidrata. Istraživana je i osjetljivost sojeva na antibiotike te je formirana krivulja rasta. Korišteni su biokemijski testovi kako bi se odredile biokemijske karakteristike sojeva: katalaza test, ureaza test i laktoza agar test. Istraživanjem je utvrđeno da većina sojeva može rasti na temperaturama višim od optimalnih te da sojevi toleriraju i kiselu i lužnatu sredinu. Utvrđeno je da sojevi rastu na nižim (1%, 2%) koncentracijama NaCl-a, dok ne toleriraju više (3%, 4%) koncentracije NaCl-a. Laktoza agar testom dokazano je da tri soja pripadaju rodu Agrobacterium. Većina sojeva posjeduje enzim ureazu dok samo manji broj njih posjeduje enzim katalazu. Provedenim mjerenjima utvrđeno je da navedeni sojevi spadaju u brzorastuće bakterije. Većina testiranih sojeva pokazala je osjetljivost na primijenjene antibiotike. Prema dobivenim rezultatima možemo zaključiti da istraživani autohtoni sojevi S. meliloti pokazuju veću otpornost na različite nepovoljne uvjete u tlu u odnosu na referentni soj S. meliloti 2011. Visoka tolerancija na nepovoljne uvjete vanjske sredine utvrđena je za autohtone sojeve I1, I5, NG1 i Z3 te se navedeni izolati mogu uključiti u daljnji program selekcije.
Keywordsbiological nitrogen fixation phenotypic characterization alfalfa (Medicago sativa L.) Sinorhizobium meliloti
Committee MembersSanja Sikora (committee chairperson)
Dubravko Maćešić (committee member)
Snježana Bolarić (committee member)
Sanja Kajić (committee member)
GranterSveučilište u Zagrebu
Agronomski fakultet
Lower level organizational unitsMikrobiologija
PlaceZagreb
StateCroatia
Scientific field, discipline, subdisciplineBIOTECHNICAL SCIENCES
Agronomy
Study programme typeuniversity
Study levelgraduate
Study programmeAgroecology
Academic title abbreviationmag. ing. agr.
Genremaster's thesis
Language Croatian
Defense date2016-07-19
Parallel abstract (English)
Nitrogen is an essential element in the growth and reproduction of plants whose deficiency in the soil is often the limiting factor in crop production. To compensate for the lack of nitrogen, very often the advantages of beneficial associations between rhizobia and legumes are utilized. Symbiotic nitrogen fixation has a unique role in the entry of nitrogen into the soil presenting an important component in achieving higher yields of different legume crops. It is important to select highly efficient rhizobial strains adapted to different soil conditions. Alfalfa (Medicago sativa L.) is a very important forage crop, which forms a symbiotic relationship with nodule bacteria Sinorhizobum meliloti. In order to increase the yield of this forage crop, the inoculation of alfalfa with high quality rhizobial strains is recommended. The main aim of this study was to select indigenous S. meliloti strains, isolated from different regions of Croatia, to adverse environmental conditions. The growth of the strains was studied at different pH values, temperatures, carbohydrate sources and different concentrations of NaCl. The sensitivity of strains to different antibiotics was tested and growth curve was formed for each isolate. Biochemical tests were used for determination of the biochemical characteristics of strains: catalase test, urease test and lactose agar test. The results showed that most of the strains can grow at temperatures higher than optimal and that strains tolerate the both acidic and alkaline environment. It was found that the strains grow at lower (1%, 2%) concentrations of NaCl, while they do not tolerate high (3%, 4%) concentration of NaCl. Lactose agar assay indicate that three strains probably belong to the genus Agrobacterium. Most strains possess the enzyme urease while only a small number of them possess the enzyme catalase. The results showed that all indigenous strains belong to the group of fast-growing rhizobia. In most cases, the sensitivity of indigenous strains to applied antibiotics was determined. The overall results suggest that indigenous S. meliloti strains are more tolerant to adverse soil conditions in relation to the reference strain S. meliloti 2011. High tolerance to unfavorable environmental conditions was determined for indigenous strains I1,I5, NG1 and Z3 and therefore, these strains could be included in further selection programs.
Parallel keywords (Croatian)biološka fiksacija dušika fenotipska karakterizacija lucerna (Medicago sativa L.) Sinorhizobium meliloti
Resource typetext
Access conditionAccess restricted to students and staff of home institution
Terms of usehttp://rightsstatements.org/vocab/InC/1.0/
URN:NBNhttps://urn.nsk.hr/urn:nbn:hr:204:433733
CommitterValentina Bezek