Isolation and Screening of Rhizosphere Bacteria from Grasses in East Kavango Region of Namibia for Plant Growth Promoting Characteristics

Abstract

A diverse group of soil bacteria known as plant growth promoting rhizobacteria (PGPR) is able to inhabit the area close to plant roots and exert beneficial effects on plant growth. Beneficial interactions between rhizospheric bacteria and plants provide prospects for isolating culturable PGPR that can be used as bio-fertilizers for sustainable crop production in communities that cannot easily afford chemical fertilizers. This study was conducted with the aim of isolating rhizospheric bacteria from grasses along the Kavango River and screening the bacterial isolates for plant growth promoting characteristics. The bacteria were isolated from rhizospheres of Phragmites australis, Sporobolus sp., Vetiveria nigritana, Pennisetum glaucum and Sorghum bicolor. The isolates were screened for inorganic phosphate solubilization, siderophore production and indole-3-acetic acid (IAA) production. The nitrogen-fixing capability of the bacteria was determined by screening for the presence of the nifH gene. Up to 21 isolates were obtained from P. australis, Sporobolus sp., S. bicolor, P. glaucum and V. nigritana. The genera Bacillus, Enterobacter, Kocuria, Pseudomonas and Stenotrophomonas, identified via 16S rDNA were represented in the 13 PGPR strains isolated. The isolates exhibited more than one plant growth promoting trait and they were profiled as follows: three phosphate solubilizers, four siderophore producers, eight IAA producing isolates and five nitrogen-fixers. These bacteria can be used to develop bio-fertilizer inoculants for improved soil fertility management and sustainable production of local cereals.

Growth Promotion Function of <em>Bacillus</em> sp. Strains Isolated From Salt-Pan Rhizosphere and Their Biocontrol Potential Against <em>Macrophomina Phaseolina</em>

“…16S rRNA gene was PCR amplified by using chromosomal DNA as a template and oligonucleotides forward 8F (5'-AGTTTGATCCTGGCTCAG-3'; annealing at position +8 ⁄ +28) and reverse 1517R (5'-ACGGCTACCTTGTTACGACT-3' annealing at position +1497 ⁄ +1517). Those two oligonucleotides were designed to amplify a 1500 bp DNA fragment and the reaction was carried out according to Grönemeyer et al [29] in an Esco SwiftTM MaxPro Thermal Cycler. The 1500 bp DNA amplified fragment was sequenced at the Bio-Fab research sequencing facility and analyzed using Basic Local Alignment Search Tool (BLAST).…”

Assessment of plant growth-promoting stress-tolerant endophytes screened from Bougainvillea glabra for the growth of Triticum aestivum L. and Zea mays

“…Previous studies (Perrig et al, 2007;Masciarelli et al, 2014) revealed the use of residing soil bacteria for lique- Table 2. Inorganic phosphate solubilization by microorganisms is of economic importance in crop nourishment, and previous studies (Haiyambo et al, 2015;Carlos et al, 2016) have already reported the application of numerous soil bacteria genera such as Achromobacter, Pseudomonas, Flavobacterium, Enterobacter, Serratia, Bacillus, Mycobacterium, Erwinia, Agrobacterium, and Escherichia as phosphate solubilizers.…”

Associative diazotrophic bacteria from forage grasses in the Brazilian semi-arid region are effective plant growth promoters

“…Inoculation of newly isolated bacteria, and of the reference strain Ab-V5, improved the growth of roots and shoots as well as N accumulation in sorghum plants ( In addition to Firmicutes, members of the g-Proteobacteria genus Stenotrophomonas were isolated from the different plants studied. This genus was also obtained from T. spicata in the Brazilian Caatinga biome (Fernandes-Júnior et al 2015) and from grasses in dry regions of India (Singh and Jha 2017) and Namibia (Haiyambo et al 2015a), as well as from areas with other environmental conditions (Gontijo et al 2018). Four Agrobacterium spp.…”