Seventeen Bradyrhizobium sp. strains and one Azorhizobium strain were compared on the basis of five genetic and phenetic features: (i) partial sequence analyses of the 16S rRNA gene (rDNA), (ii) randomly amplified DNA polymorphisms (RAPD) using three oligonucleotide primers, (iii) total cellular protein profiles, (iv) utilization of 21 aliphatic and 22 aromatic substrates, and (v) intrinsic resistances to seven antibiotics. Partial 16S rDNA analysis revealed the presence of only two rDNA homology (i.e., identity) groups among the 17 Bradyrhizobium strains. The partial 16S rDNA sequences of Bradyrhizobium sp. strains form a tight similarity (>95%) cluster with Rhodopseudomonas palustris, Nitrobacter species, Afipia species, and Blastobacter denitrificans but were less similar to other members of the ␣-Proteobacteria, including other members of the Rhizobiaceae family. Clustering the Bradyrhizobium sp. strains for their RAPD profiles, protein profiles, and substrate utilization data revealed more diversity than rDNA analysis. Intrinsic antibiotic resistance yielded strainspecific patterns that could not be clustered. High rDNA similarity appeared to be a prerequisite, but it did not necessarily lead to high similarity values between RAPD profiles, protein profiles, and substrate utilization. The various relationship structures, coming forth from each of the studied features, had low compatibilities, casting doubt on the usefulness of a polyphasic approach in rhizobial taxonomy.

This paper reports experimental work pertaining to alcoholysis between butanol and ethyl butanoate, catalyzed by an immobilized lipase in a liquid-vapor system where chemical reaction and physical separation are simultaneously carried out. The processing setup was tested for various compositions of the starting feedstock and operated under reduced pressure. Samples were withdrawn both from the boiler and the condenser, and they were chromatographically assayed for butyl butyrate. The integrated configuration tested is quite effective toward improvement of the final yield of the desired product.

Infection of legumes by rhizobia may occur by immediate intercellular penetration of root cells (crack entry) as an alternative mode to the more elaborate infection through infection threads. The intercellular spreading mode of infection is exemplified through a comprehensive description of root infection by Bradyrhizobium and nodule organogenesis in Arachis hypogaea (groundnut). The role of axillary root hairs and the processes of plant penetration and intercellular spreading, of internalization and intracellular multiplication, and of bacteroid differentiation are described. Then flavonoids and phytoalexins, Nod factors, lectins, and surface poly(oligo)saccharides pass in review. The roles of these various (macro)molecules in the chemical communication between the two symbionts are discussed. Attention is given to special features of groundnut nodules; the presence and functions of oleosomes and other bodies, the presence and functions of nodule lectins, and the evidence for the export of amides from the nodules are discussed. Finally, a speculative model for the groundnut infection process is presented.

Effects of soil acidity on groundnut-Bradyrhizobium symbiotic performance were studied in a potted, sandy soil in a glasshouse in Zimbabwe. The soil was limed to soil-pH levels of 5.0 and 6.5. Soil acidity negatively affected plant development, measured as leaf area and plant dry weight, while nodulation was enhanced. This acidity-enhanced nodulation was most evident when nodulation was caused by the indigenous Bradyrhizobium population. Effects of soil acidity differed between groundnut cultivars and Bradyrhizobium spp. strains, the former having greater importance. Two Arachis hypogaea L. Spanish-type cultivars, Falcon and Plover, performed equally well at neutral soil pH, but Falcon was more acid tolerant. Comparison of the symbiotic performance in neutral versus acid soil of two Bradyrhizobium spp.

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