Population Distribution of Phosphate-solubilizing Microorganisms in Agricultural Soil

Abstract

Phosphorus (P) is an essential macronutrient for plant growth and is mainly present in agricultural soil in unavailable forms. Phosphate-solubilizing microorganisms (PSMs) increase soil P availability. The objective of the present study was to assess the population and type of PSMs and their relationships with soil characteristics in the agricultural soil of Manokwari. Twenty-one composite soil samples (0–20‍ ‍cm) were collected at the rhizospheres of plants in the Prafi and Masni Districts. A dilution technique and plate count method on Pikovskayas agar medium were used to examine the PSM population, phosphate-solubilizing index (PSI), and various soil properties. The results obtained showed that the total population of phosphate-solubilizing bacteria ranged between 25×10 3 and 550×10 3 CFU g –1 of soil, while that of phosphate-solubilizing fungi was between 2.0×10 3 and 5.0×10 3 CFU g –1 of soil at all locations. The PSI of the isolates ranged between 1.1 to 3.6‍ ‍mm, with the most efficient and highest PSI being obtained for Bacillus sp. (strain 8) and the lowest for Pseudomonas sp. (strain 15). Six isolates found at all locations were identified at the genus level: Chromobacterium sp., Pseudomonas sp., Bacillus sp., Micrococcus sp., Caulobacter sp., and Aspergillus sp. A correlation was observed between the number of PSMs and the level of soil P availability and moisture content, indicating an increase in soil P availability with a greater abundance of PSMs in soil.

Soil type and integrated nitrogen nutrient-rice straw residue management techniques affect soil microbes, enzyme activities and yield of wheat crop

“…The increased P-solubilizers will lead to improved available P content of the soil due to production of organic acids particularly the citric and oxalic acid on decomposition of the incorporated rice straw [ 43 ]. Further, the phosphate solubilizing microbial population exhibited as shift from bacterial to more fungal counts on residue incorporation treatments [ 41 , 44 ]. The actinobacterial populations were also improved in the agri-residue incorporated treatments signifying the improved organic carbon content, mulching effect and alkaline pH of the incorporated soil [ 45 , 46 ].…”

Transcriptome profiling of genes regulated by phosphate-solubilizing bacteria Bacillus megaterium P68 in potato (Solanum tuberosum L.)

“…The trial consisted of six treatments, control group (CK) with diatomaceous soil without bacteria agent and P1, P2, P58, P68, and P69 (isolated from the rhizosphere soil of soybean) with diatomaceous soil containing 10 8 cfu·g −1 of PSB, respectively. Cfu count was determined based on the enzymatic method described by Djuuna et al (2022) : 1 g mixture was transferred using a sterile pipette to 9 ml of sterile distilled water in a test tube and stirred for 10 s to form a 10 −2 dilution. Serial dilutions to 10 −7 were then prepared using the same method.…”

“…Number of cells·g −1 (cfu·g −1 ) = (number of colonies) × (dilution factor) ( Djuuna et al, 2022 ) After 100 days, the yield (commercial tubers were ≥ 75 g) and quality (vitamin C, protein, reducing sugars, starch content, and the accumulation of N, P, and K) of potatoes were measured. Protein content was determined by the Coomassie brilliant blue G-250 colorimetric method with bovine serum albumin as the standard; vitamin C content was measured by the 2, 6-dichloroindophenol titrimetric method ( Sha et al, 2022 ); reducing sugar content was evaluated by Dinitrosalicylic Acid Reagent method ( Khatri and Chhetri, 2020 ); and starch content was determined based on the enzymatic method described by Khabou et al (1996) .…”

Nematophagous Fungi: A Review of Their Phosphorus Solubilization Potential

“…These NF potentially shorten the maturity period of crops, improve fruit quality, increase the availability of soluble P, and improve soil biodiversity [ 102 ]. Thus, there is a positive link between the application of these fungal strains and the P content in soil and plants [ 103 ].…”