Isolation of Azospirillum from diverse geographic regions

Abstract

We have isolated Azospirillum (Spirullum lipoferum) from roots of grasses of several genera collected from a number of tropical and subtropical-temperate locations. Pure cultures were obtained from a small percentage of samples; no higher percentage was secured from tropical than from other grasses. Acetylene reduction and distinctive growth in N-free soft agar deeps were inadequate to identify this genus, although helpful in initial screening. Fluorescent antibody tests with antiserum against characterized strains were helpful. There is some evidence that this genus of bacteria may be favored in the rhizoplane.

Acetylene reduction and indoleacetic acid production by Azospirillum isolates from Cactaceous plants

“…We obtained a smaller percent of Azospirilla isolation both in the rhizosphere soil and from the inside of the roots from cactaceous plants in comparison with previously reported resuits in grass roots (Drbereiner et al, 1976). However our results are consistent with others reported from roots of grasses (Tyler et al, 1979). Azospirillum populations are reported to be from 104 to l06 cells per g of dry soil or root (Hegazi et al, 1979;Magalhaes et al, 1981;Rennie, 1980).…”

“…For isolation and pure cultures, Congo Red medium (Rodriguez C~iceres, 1982) and potato infusion agar (Baldani and D6be-reiner, 1980) were employed. All Azospirillum strains were maintained in trypticase-soy agar (TSA) (Tyler et al, 1979). Succinate-fructose-salts broth (Jain and Patriquin, 1985) was used to estimate any IAA synthesized by Azospirillum.…”

“…Several reports indicate that bacteria of the genus Azospirillum have been isolated mostly from the rhizosphere (Caballero-Mellado y Vald6s, 1983;D6bereiner and Day, 1976) and roots (Lakshmi et aL, 1976;Wong and Stenberg, 1979) of forage grasses and cereals, from diverse geographic regions (Haahtela et al, 1981;Tyler et al, 1979) with much higher frequencies in tropical than in temperate-climate regions (D6bereiner et al, 1976). Azospirillum has also been isolated from roots of various non-gramineous plants, such as Ipornoea batatas, Manihot esculenta and Pteridium aquilinurn (D6bereiner, 1978), Lotus corniculatus, Hedychium coronarium and others (Kosslak and Bohlool, 1983).…”

Enhancement of Nitrogen-fixing Activity of Enterobacteriaceae Strains Isolated from Sago Palm (Metroxylon sagu) by Microbial Interaction with Non-nitrogen Fixers

“…Many consortium-based studies have suggested stimulated ARA 19,20,23,26,37,48) . The evidence presented here also supports the hypothesis that nitrogen fixation in a naturally occurring bacterium is usually affected by interactions with other microbes 44) . The reduction in the concentration of oxygen in the culture medium by indigenous dominant bacteria could result in anaerobic condition that could be preferred by NFB.…”

“…Haahtela et al 10) reported that anaerobic conditions were required for maximum nitrogenase activity of facultatively anaerobic NFB like K. pnuemoniae and E. agglomerans. It is known that dinitrogen-fixing bacteria grow best in the presence of other heterotrophic bacteria which may stimulate the nitrogen-fixing bacteria and in turn receive required N compounds 44) . Zlotnikov et al 48) showed a binary association of Bacillus firmus E3 (promoter) and Klebsiella terrigena E6 (nitrogen fixer), both of which were isolated from the rhizosphere of Dactylus glomerata: 23.7 (single culture) to 111.2 (dual culture) nmol C 2 H 4 culture −1 h −1 .…”