Evaluation of Inorganic Phosphate Solubilizing Efficiency and Multiple Plant Growth Promoting Properties of Endophytic Bacteria Isolated From Root Nodules Erythrina Brucei

Background: The majority of phosphorous in the soil is fixed and unavailable to plant nutrition, hence in scarcity. Phosphate solubilizing bacteria, the ecological engineers, are considered as the best, sustainable and eco-friendly options. The objectives of this study were to screen and evaluate inorganic phosphate solubilizing efficiency and assess multiple plant growth promoting traits of E. brucei root nodule bacterial endophytes.Results: A total of 304 nodule bacterial endophytes were screened for phosphate solubilization potential on solid PA medium among which 119 (39%) were potential tricalcium phosphate solubilizers. None of these isolates were able to form clearly visible halos on aluminum phosphate (AlPO4), Al-P or iron phosphate (FePO4), Fe-P supplemented PA medium. Out of 119 inorganic phosphate solubilizing endophytes, 40.3% were IAA producers. Based on phosphate solubilization index, the potential bacterial endophytes were identified to Gluconobacter cerinus, Acinetobacter soli, Achromobacter xylosoxidans and Bacillus thuringiensis using the 16S rRNA gene sequences analysis. All the selected isolates were potential solubilizers of the three inorganic phosphates (Al-P, Fe-P and tricalcium phosphate, TCP) included in liquid NBRIP medium. The highest values of solubilized TCP were recorded by isolates AU4 and RG6 (A. soli), 108.96 mg L-1 and 107.48 mg L-1, respectively at sampling day3 and 120.36 mg L-1 and 112.82 mg L-1, respectively at day 6. The highest values of solubilized Al-P and Fe-P were recorded by isolate RG6, 102.14 mg L-1 and 96.07 mg L-1, respectively at sampling days 3 and 6, respectively. The highest IAA, 313.61µg mL-1 was recorded by isolate DM17 (B. thuringiensis). These selected potential isolates were also HCN, NH3, and hydrolytic enzymes producers. The isolates were also varied in tolerance to eco-physiological stressors and exhibited versatility to carbon and nitrogen substrate utilization. Conclusions: The genera and species Gluconobacter cerinus, Acinetobacter soli, Achromobacter xylosoxidans and Bacillus thuringiensis are the first reports from E .brucei root nodules and Gluconobacter is also the first report to the science as phosphate solubilizer. Isolates AU4 and RG (A. soli) could be potential bio-inoculant candidates for the growth enhancement of the host plant for better agro-forestry practices in acidic and alkaline soils in Ethiopia.

Draft Genome Sequence and Annotation of Acinetobacter soli AS15, Isolated from an Irish Hospital

We report the draft genome sequence of Acinetobacter soli AS15, which was isolated in 2018 from a rectal screen of a patient at St. Vincent’s University Hospital (Dublin, Ireland). The draft genome sequence is 3,589,002 bp and was assembled into 82 contigs.

Exploitation of siderophore producing bacteria Acinetobacter soli (MTCC-5918) for lipids and reactive oxygen species in Chlorella variabilis (ATCC- PTA 12198) through co-cultivation

Background Increased iron uptake via siderophores triggers a series of physiological processes and generation of reactive oxygen species (ROS) which causes damage to proteins, lipids, carbohydrates, resulting into micro algal cell lysis. Moreover, there are reports mentioning oxidative stress is a mediator for increased lipid accumulation in microalgae. The main aim of this study is co-cultivation of the bacteria Acinetobacter soli (MTCC- 5918) and the microalgae Chlorella variabilis (ATCC-PTA 12198) under iron limiting conditions and the threshold value of iron that trigger oxidizing stress to microalgae. Further, the ROS generation in the microalgae C. variabilis was determined in terms of OH, SO2 and H2O2 concentration in the cells while co-cultivation. Results The co-cultured biomass contains (45.92 ± 0.74%) lipid content which was about 21% higher than that of the axenically grown microalgae. Carbohydrate content also increased to 40% than that of the control culture. Oxidative stress is a mediator for increased lipid accumulation in microalgae. As growth inhibition triggered due to the generation of high ROS toxicity during iron deficiency an increase in concentration of OH and H2O2 content was observed. In iron sufficient medium ash content of co-cultivated microalgae showed 32% and in iron deficient medium showed 14.23% which shows 44% decrease of ash content. Our novel approach significantly outperforms the involvement of different reactive oxygen species (ROS) in induction and in regulation of chelator release from cells at adequate Fe supply, which is also affecting the growth,lipids, carbohydrates, proteins, pigments, etc. Conclusions The findings of the present study highlights that oxidative stress is a mediator for increased lipid accumulation in microalgae that simultaneously becomes an alternative strategy for the improvement of biofuel potential in C. variabilis. The study portraysthe significance of co-cultivation of A. soli and C. variabilis induced oxidative stress (ROS generation) in microalgae caused due to higher uptake of iron via siderophore

Bacterias endófitas de la raíz en líneas de maíces tolerantes y susceptibles a sequía

<p>El maíz (<em>Zea mays</em>) ocupa el segundo lugar como alimento en el mundo y la sequía limita su productividad. Las plantas albergan bacterias endófitas que influyen en la sanidad y tolerancia a la sequía. El objetivo de esta investigación fue estimar la densidad y diversidad de las bacterias endófitas cultivables de la raíz en siete líneas homocigóticas de maíces tolerantes y siete susceptibles a sequía en tres localidades de México durante tres ciclos del cultivo. La densidad y diversidad de las poblaciones bacterianas se evaluó mediante conteo directo en placas y se identificaron por PCR. Los resultados identificaron tres grupos de bacterias endófitas: 1) altamente frecuentes (<em>Bacillus subtilis</em>, <em>Bacillus megaterium</em> y <em>Pseudomonas geniculata)</em>, 2)<em> </em>frecuentes (<em>Bacillus firmus</em>, <em>Pseudomonas hibiscola</em> y <em>Sinorhizobium meliloti)</em> y 3) baja frecuencia (<em>Acinetobacter soli, Stenotrophomonas maltophila </em>y<em> Burkholderia gladioli</em>. El análisis de varianza (ANOVA) mostró diferencias significativas (p?0,05)<strong> </strong>en la densidad (_Log10UFC g^-1 de raíz) de población por localidad, ciclo de cultivo, días después de siembra y líneas de maíz. La densidad de <em>Bacillus subtilis, Pseudomonas hibiscola </em>en la localidad de El<em> </em>Batán<em> y Bacillus megaterium, Sinorhizobium meliloti</em> en Tlaltizapán, fueron significativamente mayores en las líneas de maíz tolerantes que en las susceptibles a sequía. </p>