Competitiveness and communication for effective inoculation byRhizobium, Bradyrhizobium and vesicular-arbuscular mycorrhiza fungi

After a short summary on the ecology and rhizosphere biology of symbiotic bacteria and vesicular-arbuscular (VA) mycorrhiza fungi and their application as microbial inocula, results on competitiveness and communication are summarized. Stress factors such as high temperature, low soil pH, aluminium concentrations and phytoalexins produced by the host plants were studied withRhizobium leguminosarum bv.phaseoli andRhizobium tropici onPhaseolus beans. Quantitative data for competitiveness were obtained by usinggus + (glucoronidase) labelled strains, which produce blue-coloured nodules. ForPhaseolus-nodulating rhizobia, a group specific DNA probe was also developed, which did not hybridize with more than 20 other common soil and rhizosphere bacteria. Results from several laboratories contributing to knowledge of signal exchange and communication in theRhizobium/Bradyrhizobium legume system are summarized in a new scheme, including also defense reactions at the early stages of legume nodule initiation. Stimulating effects of flavonoids on germination and growth of VA mycorrhiza fungi were also found. A constitutive antifungal compound in pea roots, -isoxazolinonyl-alanine, was characterized

Isoliquiritigenin, a strong nod gene- and glyceollin resistance-inducing flavonoid from soybean root exudate.

Isoflavonoid signal molecules from soybean (Glycine max (L.) Merr.) seed and root exudate induce the transcription of nodulation (nod) genes in Bradyrhizobium japonicum. In this study, a new compound with symbiotic activity was isolated from soybean root exudate. The isolated 2',4',4-trihydroxychalcone (isoliquiritigenin) is characterized by its strong inducing activity for the nod genes of B. japonicum. These genes are already induced at concentrations 1 order of magnitude below those required of the previously described isoflavonoid inducers genistein and daidzein. Isoliquiritigenin is also a potent inducer of glyceollin resistance in B. japonicum, which renders this bacterium insensitive to potentially bactericidal concentrations of glyceollin, the phytoalexin of G. max. No chemotactic effect of isoliquiritigenin was observed. The highly efficient induction of nod genes and glyceollin resistance by isoliquiritigenin suggests the ecological significance of this compound, although it is not a major flavonoid constituent of the soybean root exudate in quantitative terms

Analisis Mutu Organoleptik Kopi Bubuk Arabika (Coffea Arabica) Bittuang Toraja

Kopi arabika (Coffea arabica) mempunyai mutu cita rasaterbaik dibandingkan jenis kopiyang lain, dengan ciri biji berbentuk putih kehijauan dan daun hijau tua. Secara umum,pengolahan kopi di Indonesia terdiri dari pengolahan secara kering, secara basah, dan luwak.Penelitian ini bertujuan untuk mengetahui mutu kopi arabika secara organoleptik (warna, tekstur,aroma, rasa) melalui proses pengolahan bahan baku (kering, basah, luwak). Berat biji kopiarabika untuk masing-masing perlakuan adalah 1000 gram. Setelah dilakukan prosespengolahan, biji kopi disangrai dan digiling, dilakukan analisis rendemen dan kadar air, kemudiandilakukan penyeduhan dengan air panas 500 mL. Setelah itu dilakukan pengamatan sensori(warna, tekstur, aroma, rasa). Hasil penelitian menunjukkan bahwa rendemen tertinggi padaperlakuan luwak yaitu 95,7% dan kadar air yang tertinggi pada perlakuan kering yaitu 4,86%,dimana kadar air ini sesuai dengan persyaratan Standar Nasional Indonesia (SNI) yaitu maksimal7%. Berdasarkan uji organoleptik, warna terbaik adalah perlakuan basah dengan nilai sebesar4,49; tekstur terbaik adalah perlakuan kering sebesar 3,85; dan aroma serta rasa terbaik adalahperlakuan luwak dengan nilai masing-masing sebesar 5,17 dan 3,83