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Aims: The identification, differentiation and characterization of indigenous Saccharomyces sensu stricto strains isolated from Croatian vineyards and the evaluation of their oenological potential. 
Methods and Results: A total of 47 Saccharomyces sensu stricto strains were isolated from Chardonnay grapes and identified by physiological and molecular genetic methods. By using the standard physiological and biochemical tests, six isolates were identified as Saccharomyces cerevisiae and 41 as Saccharomyces paradoxus. However, PCR–RFLP analyses of the internal transcribed spacer (ITS1) region of the 18S ribosomal DNA identified 12 of the isolates as S.cerevisiae and 35 as S. paradoxus. Fermentation trials in a grape juice medium showed that these isolates ferment vigorously at 18 °C and display tolerance to high levels of ethanol. None of these isolates appeared to produce either hydrogen sulphide or killer toxins. 
Conclusion:Saccharomyces paradoxus, possessing potentially important oenological characteristics, occurs in much higher numbers than S. cerevisiae in the indigenous population of Saccharomyces sensu stricto strains in Croatian vineyards. 
Significance and Impact of the Study: This study forms an essential step towards the preservation and exploitation of the hidden oenological potential of the untapped wealth of yeast biodiversity in the Croatian grape‐growing regions. The results obtained demonstrate the value of using molecular genetic methods, such as PCR–RFLP analyses, in conjunction with the traditional taxonomic methods based on phenotypic characteristics in such ecotaxonomic surveys. The results also shed some light on the ecology and oenological potential of S.paradoxus, which is considered to be the natural parent species of the domesticated species of the Saccharomyces sensu stricto group.

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Inoculation of leguminous seeds with selected rhizobial strains is practised in agriculture to ameliorate the plant yield by enhanced root nodulation and nitrogen uptake of the plant. However, effective symbiosis between legumes and rhizobia does not only depend on the capacity of nitrogen fixation but also on the entire nitrogen turnover in the rhizosphere. We investigated the influence of seed inoculation with two indigenous Sinorhizobium meliloti strains exhibiting different efficiency concerning plant growth promotion on nitrogen turnover processes in the rhizosphere during the growth of alfalfa. Quantification of six target genes (bacterial amoA, nirK, nirS, nosZ, nifH and archaeal amoA) within the nitrogen cycle was performed in rhizosphere samples before nodule formation, at bud development and at the late flowering stage. The results clearly demonstrated that effectiveness of rhizobial inocula is related to abundance of nifH genes in the late flowering phase of alfalfa. Moreover, other genes involved in nitrogen turnover had been affected by the inocula, e.g. higher numbers of amoA copies were observed during flowering when the more effective strain had been inoculated. However, the respective gene abundances differed overall to a greater extent between the three plant development stages than between the inoculation variants.

Seven indigenous yeast strains of Saccharomyces paradoxus previously isolated and identified using molecular and physiological methods were tested for their fermentation abilities. Chemical analyses of produced wines showed differences compared with the Saccharomyces cerevisiae strain used as a control. The examined S. paradoxus strains showed good fermentation vigour, ethanol tolerance and difference in the fermentation rate. Four of seven analysed S. paradoxus strains (RO66, RO54, RO11 and RO134) metabolised sugar up to 1 g L-1. The total amount of higher alcohol was lower compared with S. cerevisiae wines. Strain RO83 was able to degrade up to 40% malic acid and can be used for biological deacidification. Sensory evaluation of dry and semidry wines underlined good enological properties and positive influence of tested wine strains on final wine quality. All these properties of S. paradoxus strains pointed out the possibility of their application in wine industry. © 2006 Institute of Food Science and Technology Trust Fund

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S. SIKORA, S. REDŽ EPOVIĆ , I. PEJIĆ A N D V . K O ZU MP L IK . 1997. RAPD fingerprinting was used for strain identification and the assessment of genetic diversity within a field population of Bradyrhizobium japonicum. Total genomic DNAs from 13 field isolates and two inoculant strains were amplified using six different 10-mer primers. Different and informative band patterns were obtained for all strains analysed. Cluster analysis unexpectedly revealed that none of the field isolates was identical to inoculant strains which were regularly used for soybean inoculation. Among field isolates two highly divergent groups were determined. The results indicate that RAPD is a very discriminative and efficient method for differentiating and studying genetic diversity of B. japonicum strains.