Isolation and Characterization of Plant Growth-Promotion Diazotrophic Endophytic Bacteria Associated to Sugarcane (Saccharum officinarum L.) Grown in Paraíba, Brazil

Sugarcane is an important Brazilian commodity, being usually cultivated in soils with low natural fertility. This study aimed to isolate diazotrophic endophytes from sugarcane tissues and evaluate the morphological and physiological characteristics of their colonies as well as their plant growth-promoting (PGP) traits in select diazotrophic endophytic bacteria. Fifty-six bacterial isolates were identified in the sugarcane tissues, and these isolates presented distinct morphological and physiological traits. A total of thirty-five bacterial isolates were biochemically evaluated. Overall, Bacillus was the dominant genus. Isolates of Methylobacterium spp. and Brevibacillus agri were present only in leaves, while Herbaspirillum seropedicae occurred only in stems. Except to IPA-CF45A, all isolates were nitrogenase positive. All endophytes exhibit production of indol 3-acetic acid. Over 50% of endophytes solubilize phosphate, release N-acyl homoserine lactones, and present the activity of 1-aminocyclopropane-1-carboxylic acid deaminase, catalase, lipase and protease. The network analysis showed that isolates belonged to Burkholderia, Herbaspirillum, and Methylobacterium interact with Bacillus. Bacterial endophytes exhibited distinct morphological, physiological, and PGP traits that are useful for sustainable agriculture, highlighting the isolates IPA-CC33, IPA-CF65, IPA-CC9 and IPA-CF27. Further studies on the effects of these diazotrophic endophytes and their potential for providing microbial inoculants for improving sugarcane fields will provide valuable information to maintain the sustainability and environment quality.National Council for Scientific and Technological Development 426655/2018-

Inoculation of plant-growth-promoting rhizobacteria in Myracrodruon urundeuva Allemão supports in tolerance to drought stress

This study evaluated the influence of Azospirillum lipoferum on the growth of Myracroduon urundeuva (Anacardiaceae) plants under drought stress, by means of biometric, physical–chemical and biochemical parameters. The association of A. lipoferum with the roots of the plants provided increases of 30% root length, 50% root dry weight, 34% shoot dry weight and 10% soluble protein content. The inoculated plants still maintained 5% higher leaf water potential than those not inoculated and lower membrane damage. Furthermore, the inoculated plants shown less leaf fall and dark green leaves, confirmed by maintenance of the highest levels of chlorophyl a, b and total. On the other hand, superoxide dismutase activity was significantly lower in the inoculated plants, possibly due to the induction of a non-enzymatic protective feature. In this way, the inoculation of PGPR in M. urundeuva can be an alternative for the production of plants that are more tolerant to drought stress

Evolution of nutrient availability in maturation phase of composting using proportions of different residues inoculated with Beijerinckia indica

<div><p>ABSTRACT. Organic matter has low N content; however, organic matter may be enriched by inoculation with selected diazotrophic bacteria. The aim of the paper was to evaluate the effects of biofertilizer produced by mixing different types and proportions of organic matter inoculated with the diazotrophic bacteria Beijerinckia indica. The experiment consisted of plastic trays (6 L) containing 5 kg of three different types of organic matter (filter mud cake, earthworm compost, and crop residue) applied in the following proportions (v:v:v): 1-(5:0:0), 2-(4:1:0), 3-(4:0:1), 4-(3:2:0), 5-(3:1:1), 6-(3:0:2), 7-(2:3:0), 8-(2:2:1), 9-(2:1:2), 10-(2:0:3), 11-(1:4:0), 12-(1:3:1), 13-(1:2:2), 14-(1:1:3), 15-(1:0:4), 16-(0:5:0), 17-(0:4:1), 18-(0:1:4), 19-(0:3:2), 20-(0:2:3), and 21-(0:0:5). Samples were collected following inoculation with B. indica at 0, 10, 20, 30, and 40 days of the maturation phase. The chemical analyses were: pH (H2O), total C and N, available P and K, and exchangeable Na+, Ca+2, Mg+2. The treatments with the best results showed significant effects following the maturation phase. The exceptions were C and N, which presented only individual effects. In general, the organic matter proportions (5:0:0), (3:2:0), and (2:3:0) resulted in a significant increase in the availability of nutrients. Biofertilizers with optimal organic matter proportions may be used to produce organic substrates that are more effective and have the potential to be applied as alternatives to soluble NPK fertilizers.</p></div