The effectiveness of methanotrophic bacteria and Ochrobactrum anthropi to reduce CH4 and N2O emissions and to promote paddy growth in lowland paddy fields

Aims: Paddy field is one of the sources of greenhouse gasses such as methane (CH4) and nitrous oxide (N2O), which causes global warming and other negative effects in agricultural sector. An alternative to optimize paddy productivity and reduce emissions of CH4 and N2O is by using methanotrophic bacteria and Ochrobactrum anthropi BL2. Methodology and results: This study consisted of two parts, i.e. positive control and experimental treatments. Positive control consisted of 250 kg/ha NPK inorganic fertilizer NPK (15:15:15) (100% of the recommended normal dose) without any methanotrophic bacteria. Meanwhile the experimental treatment consisted of 50 kg/ha inorganic fertilizers NPK (20% of the recommended normal dose) with methanotrophic bacteria (Methylocystis rosea BGM 1, M. parvus BGM 3, Methylococcus capculatus BGM 9, Methylobacter sp. SKM 14) and N2O reducing bacteria (Ochrobactrum anthropi BL2). Using weight indicator of 1000 grams, all the bacteria are capable of increasing paddy productivity by 42.07%, compared to conventional method which can only increase the productivity by 2.51% (Cepy and Wangiyana, 2011). The increasing productivity and growth of paddy plants were due to the nitrogen fixation activity of M. rosea BGM 1, M. capculatus BGM 9, and Methylobacter sp. SKM 14. In the experimental treatment using bacteria, the emission of CH4 and N2O was reduced with the highest CH4 and N2O sinks of 24018.8 mol CH4/day/ha and 68.48 mol N2O/day/ha, respectively. However, the positive control treatment with 100% of the recommended fertilizer dose showed the highest CH4 and N2O emissions which were up to 74346.45 mol CH4/day/ha and 26.21 mol N2O/day/ha, respectively. Conclusion, significance and impact study: All the methanotropic bacteria and O. anthropi BL2 are significantly increase paddy production, compared to positive control treatment. The addition of bacteria in paddy fields results in CH4 and N2O sinks.

Identification of phylloplane yeasts from paper mulberry (Broussonetia papyrifera (L.) L'Hér. ex Vent.) in Java, Indonesia

Aims: Broussonetia papyrifera (Saeh plant) has many qualities, the inner bark was the material for ‘dluwang’ papers on which Indonesian historical manuscripts were written, and the leaves have bioactive constituents of medicinal value, and antifungal activities. We investigated the diversity of yeast species associated with leaves from 6 months and 1.5 yearold plants, which is prerequisite to understand the phylloplane yeasts and plant interaction. Methodology and results: The yeasts were isolated from fresh leaves by washing and membrane filtration methods. A total of 16 leaf samples of 6 months and 1.5 year-old plants were collected from four locations in Java, Indonesia, and 2,543 yeast isolates were obtained. Based on similarity of colony morphology, 82 representative yeast isolates were selected and identified based on the sequence analyses of internal transcribed spacer (ITS) regions of rDNA. The identification result showed that they consisted of 17 genera and 32 species. Thirty six of representative yeast isolates belong to 11 genera (18 species) of the phylum Ascomycota and forty six isolates belong to 6 genera (14 species) of the phylum Basidiomycota. Phylogenetic trees showed that the yeast isolates are phylogenetically diverse and distributed in the phyla of Ascomycota (classes Saccharomycetales and Dothideomycetes) and Basidiomycota (classes Microbotryomycetes, Tremellomycetes, and Ustilaginomycetes). Conclusions, significance and impact of study: The phylloplane yeasts of B. papyrifera (Saeh plant) were taxonomically heterogeneous. This is the first report of the isolation and identification of phylloplane yeasts from B. papyrifera. Phylloplane yeasts may possess antagonistic activity to fungal plant pathogens in their natural habitats.