A microcosm experiment was conducted to study the effect of the application of rice straw and compost to a soil on the bacterial communities associated with five species of microcrustaceans in the floodwater of paddy fields based on RFLP analysis. PCR products for bacterial 16S rDNA were digested with four restriction endonucleases (Hinf I, Sau3A I, Hae III, EcoR I). The results showed that the RFLP patterns of the bacterial communities were distinctly different among the microcrustaceans, although DNA fragments common to Tanycypris sp., Cypretta sp., and Heterocypris sp. were recognized. Bacterial communities associated with Tanycypris sp. showed the smallest number of fragments among the microcrustaceans studied. Rice straw and compost application exerted a negligible effect on the band patterns from Cypretta sp. and Moina sp., respectively. Cluster analysis and principal component analysis enabled to separate the band patterns into 2 groups with a total of 4 subgroups: I-1. Moina sp., I-2. Mesocyclops sp., II-1. Tanycypris sp. and Cypretta sp., and II-2. Heterocypris sp. The results indicated that the bacterial association with the microcrustaceans was primarily determined by the genus and species of hosts. Effects of rice straw and compost application on the bacterial communities associated with Moina sp. and Cypretta sp. and the duration of flooding on the bacterial communities associated with all the micro crustaceans were also observed, although the effects were not appreciable compared to those of the kind of host microcrustaceans.

Changes in the activities of soil enzymes (acid and alkaline phosphatases, β-glucosidase, and arylsulfatase) associated with continuous cultivation of cassava, sugarcane, and pineapple were studied in middle terrace areas of Lampung Province, South Sumatra, Indonesia. Soil samples were collected from fields continuously cultivated with cassava for the period ranging from 0 to 10 y, with sugarcane from 0 to 20 y, and with pineapple from 0 to 10 y. Continuous cultivation did not show conspicuous effects on soil pH, and contents of total N, organic C, and available P as well as soil enzymatic activities. However, the changes in the activities of the soil enzymes generally showed a significant relationship with the contents of soil organic C and total N.

Aeny TN, Prasetyo J, Suharjo R, Dirmawati SR, Efri, Niswati A. 2018. Isolation and Identification of actinomycetes potential as the antagonist of Dickeya zeae pineapple soft rot in Lampung, Indonesia. Biodiversitas 19: 2052-2058. This study was aimed to collect and identify actinomycetes from the rhizosphere of pineapple with the potency as a biocontrol agent of Dickeya zeae, the pathogen of pineapple soft rot. Soil samples were collected from four different pineapple plantations in Lampung Province, in December 2016. Samples were air-dried, serially diluted, and plated on modified ISP2 medium and several single characterized colonies were sub cultured and purified. The growing colonies were grouped into different colour series based on their aerial-mycelia and substrate-mycelia colors. Antagonistic activity of the actinomycetes isolates were evaluated against Dickeya zeae by agar diffusion method using the same medium agar lawn with the bacterial cultures. Selected antagonistic actinomycete isolates with the biggest clear zone formation were further characterized and identified molecularly based on 16S rDNA sequences. The results showed that as many as 34 actinomycete isolates collected from pineapple rhizosphere produced clear zones. Two isolates, namely GGF2-i5 and GGF4-i18, presented the biggest clear zone were proposed as the potential antagonist strains against D. zeae and identified as Streptomyces parvulus and Streptomyces hygroscopicus subsp. hygroscopicus, respectively. Both of the 16S rRNA gene sequences from those strains were deposited in the GenBank with the accession number MH170279 and MH170280, respectively.