Muniru K. Tsanuo

Isoschaftoside, a C-glycosylflavonoid from Desmodium uncinatum root exudate, is an allelochemical against the development of Striga

In East African small-holder farming of maize, the cattle forage legume, Desmodium uncinatum is used as an intercrop due to its allelopathic inhibition of parasitism by Striga hermonthica, an obligate parasitic weed that can devastate the maize crop. Bioassay-guided fractionation of the root extract of D. uncinatum revealed isoschaftoside to be the main compound in the most potent fraction inhibiting growth of germinated S. hermonthica radicles. Bioassays repeated with isoschaftoside isolated from a different plant source, Passiflora incarnata, proved it to be a biologically active component. Analysis of the root exudates produced by hydroponically grown D. uncinatum showed isoschaftoside to be present in the hydroponic media at biologically active concentrations of 10-100 nM.

Benzoic acid-degrading bacteria from the intestinal tract of Macrotermes michaelseni Sjöstedt

The intestinal tracts of termites host a wide variety of microbial symbionts, which have been implicated in degradative processes. In this study, a fungus‐cultivating termite, Macrotermes michaelseni was found to harbor 2.2 × 106 bacterial cells per ml of gut homogenates capable of degrading benzoic acid. Two benzoic acid degrading bacteria were isolated from the highest dilution of gut homogenates in oxic media with benzoic acid as the sole carbon source. Isolate CBC was related to Stenotrophomonas maltophila LMG 958T, Xanthomonas campestris DSM 3586T and Stenotrophomonas acidaminophila DSM 13117T with a sequence similarity of 98.3%, 94.7% and 94.2%, respectively. Isolate CBW was related to Enterobacter aerogenes JCM 1235T and Raoultella ornithinolytica ATCC 31898T with sequence similarity of 98.4% and 97.8%, respectively. In addition to growing on benzoic acid (up to 9 mM) aerobically, isolate CBW also degraded benzoic acid under anoxic conditions with nitrate as electron acceptor. Isolate CBC did not degrade bezoic acid with nitrate but could degraded resorcinol under oxic conditions. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Rhodococcus opacus strain RW, a resorcinol- degrading bacterium from the gut of Macrotermes michaelseni

The population of resorcinol degrading bacteria in the intestinal tract of fungi-cultivating termite, Macrotermes michaelseni , was estimated to be 6.8 × 10 2 cells/ml. A gram-positive bacterium designated RW, capable of degrading resorcinol, was isolated from the highest positive dilution. Isolate RW could also degrade phenol and benzoic acid aerobically, and anaerobically using nitrate as an electron acceptor. The isolate is a rod-shaped bacterium that exhibited evolutionary relatedness with the genus Rhodococcus, as determined by phenotypic traits and physiological tests, and a 16S rRNA gene sequence similarity value of 99.6% to the closest Rhodococcus opacus strain. On the basis of these results isolate RW is proposed as a new strain in the species R. opacus . The ability of the isolate to degrade resorcinol, phenol and benzoic acid makes it a potential candidate for use in bioremediation of environments contaminated by such or related compounds. African Journal of Biotechnology Vol. 4 (7), pp. 639-645, 2005