Eksplorasi Bakteri Diazotrof dari Rizosfer Tanaman Bawah Merah (Allium ascalonicum L.) di Brebes, Jawa Tengah

Penelitian ini bertujuan untuk mengeksplorasi bakteri diazotrof yang mampu menambat nitrogen dan menghasilkan hormon IAA dengan cara menyeleksinya dari rizosfer tanaman bawang merah di Brebes, Jawa Tengah. Penelitian dilakukan selama 6 bulan (Januari-Juni 2020). Penelitian ini terdiri dari pengambilan sampel tanah perakaran bawang merah di Brebes, Jawa Tengah, isolasi bakteri tanah pada medium Yeast Mannitol Agar+Congo red, Ashby, dan Caceres, uji produksi IAA metode Salkowski, uji kemampuan penambatan nitrogen metode Kjeldahl, dan identifikasi bakteri. Sebanyak sembilan isolat bakteri diazotrof yang mampu menghasilkan IAA telah berhasil diisolasi. Kesembilan isolat tersebut mampu menghasilkan IAA dengan konstentrasi antara 3,05-3,51 ppm, dengan isolat LAR3 sebagai penghasil IAA tertinggi. Hasil perhitungan kemampuan menambat nitrogen bebas dengan metode Kjeldahl dari 6 isolat terbaik penghasil IAA, mampu menghasilkan konsentrasi berkisar antara 3,15-88,55 ppm, dengan isolat LAR5 sebagai penghasil nitrogen tertinggi. Hasil identifikasi menunjukkan kesembilan isolat bakteri yang didapatkan termasuk dalam 3 kelompok bakteri yang berbeda, yaitu empat isolat termasuk spesies anggota genus Rhizobium (isolat LAR3,LAR5,LBR1,dan LCR3), tiga isolat adalah spesies anggota genus Azospirillum (isolat LAA4,LAA5, dan LCA1), dan dua isolat termasuk spesies anggota genus Azotobacter (isolat LBZ2 dan LBZ3).

Rhizospheric rhizobia identification in maize (Zea mays L.) plants

Rhizobia have been studied for the symbiosis that they establish with the roots of legumes. However, the colonization and promotion of growth in non-leguminous plants has also been demonstrated. The aim of this work was the biochemical and molecular identification of rhizosphere rhizobia present inthe rhizosphere of two commercial maize cultivars. Cultivableisolates were obtained in yeast-mannitol-agar (YMA) mediumfrom rhizospheric soil and the rhizoplane. The cultural (size,color, mucus, etc.), morphological, and staining (cell shape,response to staining and sporulation) characteristics weredetermined as well as isolate responses to eight biochemicaltests (acid-base production, citrate, oxidase, catalase, H2Sproduction, urease, gelatinase and the oxidative-fermentativeassay) that are valuable for rhizobia identification. The genuswas determined by 16S rDNA gene sequencing. We obtained 81total isolates of which 30.86% showed the cultural, morphological and staining characteristics expected for rhizobia and only 20% of these corresponded to the genus Rhizobium.

Assessment of chromium induced alterations on gut bacterial population of E. eugeniae

The aim of the present study was to enumerate the diversity of gut bacterial population of epigeic earthworm species, E. eugeniae exposed to heavy metal. Adult earthworms were treated with three different doses (0.06%, 0.13% and 0.19% w/v) of potassium dichromate (K2Cr2O7) for this purpose. The gut samples were serially diluted and inoculated in seven distinct media viz. Jensen's media, King’smedium B base, Burk’s media, Yeast Mannitol Agar media, Vogel- Johnson agar base media, Luria Bertani Broth Miller and Nutrient agar media. Dose dependent decrease in bacterial population was observed in treated worms when compared with control. Maximum percent change (62.59%) in bacterial population was observed in Burk’s media when exposed to 0.19% chromium. The results revealed that chromium alters the microbial population present in gut of earthworms. Therefore, changes in earthworms’ gut microbial community due to soil management practices can also be used as markers of soil fertility and quality.

Physiological and Molecular Assessment of Sesbania Root Nodules Bacteria from Different Iraqi Areas for Salt Tolerance

Thirty two isolates of aerobic gram-negative bacteria associated with Sesbania sesban grown in different saline Iraqi soils was identified according to morphological and physiological characteristics, cultured on yeast-mannitol agar medium (YEMA) supplemented with different NaCl concentrations. It was indicated that 53.12% of isolates were highly tolerant to salinity, tolerated from 4.0 to 5.0 w/v NaCl. All thirty two Rhizobia isolates performed positive strong reaction to Catalase enzyme except for three were negative to this enzyme. Concerning exo-polysaccharide (EPS) production the isolates displayed a significant difference between them and that salt tolerance isolates gave a high amount of EPS production in compare to the sensitive ones. As for antibiotic sensitivity of Sesbania isolates data revealed that 83% of isolates were highly resistant to Ampicilin at 50 µgml-1, the cluster analysis based on all phenotypical and physiological characters divided the isolates into two major groups, the first group included one isolate Ses10, which was salt moderate tolerant. The second group included the rest of isolates which splits into two subgroups with 6% similarity, the first subgroup comprised all sensitive isolates plus one salt moderate tolerant isolate (Ses9).The assumption that district environmental conditions plays a vital role on field survival of bacteria, give rise to the use of PCR methods to identify Rhizobia. In this study the genetic divergence of fast nodulating bacteria connected with Sesbania in Iraq was examined. A selection of Rhizobia isolates were characterized by RAPD –PCR. Amplification of genomic DNA using three random primers (RAPD) gave various bands, the results revealed that most efficient and highest discrimintory power primer was 35.4% and 37% respectively for primer OPA-10. The cluster analysis based on RAPD-PCR amplification results showed two divergent groups with 15% similarity, the first group included two salt sensitive Ses17 and Ses28, and the second major group comprised all salt moderate and tolerant isolates.

Yabani Baklagil Bitkilerinden, Mikrobiyal Gübre Olarak Kullanılan Rhizobium Spp. Bakterilerinin İzolasyonu

In our study used wild leguminous plants (Medicago sativa, M. lupulina and M. varia ) Erzurum belongs to the high altitude (2000 - 2500m ) regions ( Palandöken mountain, Alibaba mountain, Turnagöl mountain, Hasanbaba mountain, Eğerli mountain, Yıldırım mountain, Çubuklu mountain, Deveboynu locality, Kayakyolu locality, Telsizler and Dumlu hill ) were collected during the months of June and July. Nodules were obtained from this plant were sterilized, YMA (Yeast Mannitol Agar) plates were streaked and petri dishes 28+1ºC were incubated for 3-5 days. Colonies appear after incubation typically constitute (white, clear or slightly opaque, mucosity, round, raised) 39 isolates were selected and transferred to tubes and refrigerated YMA were stored at +4ºC. In the next stage, cytological and biochemical analyzes of these isolates were studied to determine. For this purpose isolates; YMA containing bromothymol blue and congo red reproduction, gram stain reaction, movement and subjected to catalase and oxidase tests were evaluated. The cytological and biochemical analysis of results showed that 28 of 39 strains belonged to Rhizobium spp.

Biossorção de metais presentes na DAM utilizando Rhodococcus opacus

O presente trabalho tem como objetivo avaliar a biossorção de metais presentes em uma amostra sintética de drenagem ácida de mina, determinando o tempo de equilíbrio, a quantidade de metal captado e removido e, também, as mudanças ocorridas na biomassa. Para tanto, os ensaios foram realizados mantendo-se constantes a temperatura (25ºC), o pH (2,6), a concentração de biomassa (1g.L-1) e sob agitação de 175rpm. Como biossorvente foi utilizada uma massa fixa de bactérias gram-positivas Rhodococcus opacus no estágio de morte que foi crescida em meio YMA (yeast mannitol agar), durante 24h, a 28ºC e sob agitação de 150rpm. Após o processo biossortivo as amostras foram centrifugadas: o sobrenadante foi analisado através de análise de absorção atômica e a biomassa foi caracterizada através análises de microscopia eletrônica de varredura (MEV). Os resultados mostraram que a captação máxima ocorre em torno de 1 minuto e representa 48,2mg.g-1, o que corresponde a aproximadamente 11,7% de remoção. As mudanças verificadas nas análises de MEV indicam que houve interação entre os íons metálicos e a biomassa.

An Assessment of Different Techniques for Inoculating Phaseolus vulgaris with Rhizobium

SUMMARYA technique to better ensure reliable nodulation of pot-grown, P. vulgaris plants with cultured strains of Rhizobium is described. Nodulation, dinitrogen fixation (acetylene reduction) activity and growth of 28-day-old plants were all stimulated markedly when seeds had been inoculated with cultured Rhizobium phaseoli suspended in alginate gel (Agrigel) rather than in sucrose solution. Nodulation attributes of plants inoculated with R. phaseoli strain RCR 3644 which had been sub-cultured repeatedly on yeast mannitol agar slopes were consistently inferior to those recorded for the same strain but recently cultured from a freeze-dried sample. Some of the potential problems with open pot culture of nodule-dependent legumes are discussed.

An Assessment of Different Techniques for Inoculating Phaseolus vulgaris with Rhizobium

SUMMARYA technique to better ensure reliable nodulation of pot-grown, P. vulgaris plants with cultured strains of Rhizobium is described. Nodulation, dinitrogen fixation (acetylene reduction) activity and growth of 28-day-old plants were all stimulated markedly when seeds had been inoculated with cultured Rhizobium phaseoli suspended in alginate gel (Agrigel) rather than in sucrose solution. Nodulation attributes of plants inoculated with R. phaseoli strain RCR 3644 which had been sub-cultured repeatedly on yeast mannitol agar slopes were consistently inferior to those recorded for the same strain but recently cultured from a freeze-dried sample. Some of the potential problems with open pot culture of nodule-dependent legumes are discussed.