Effect of pH and Carbon Source on Phosphate Solubilization by Bacterial Strains in Pikovskaya Medium

Abstract

Phosphate-solubilizing bacteria (PSB) transform precipitated inorganic phosphorus into soluble orthophosphates. This study evaluated the efficiency of tricalcium and iron phosphate solubilization in Pikovskaya medium using five bacterial strains (A1, A2, A3, A5, and A6) cultured in acidic and alkaline pH levels. The bacterial strain that proved to be more efficient for P solubilization and was tolerant to pH variations was selected for assessing bacterial growth and P solubilization with glucose and sucrose in the culture medium. The bacterial strains were identified through 16S rRNA gene sequencing as Pseudomonas libanensis A1, Pseudomonas libanensis (A2), Bacillus pumilus (A3), Pseudomonas libanensis (A5), and Bacillus siamensis (A6). These five bacterial strains grew, tolerated pH changes, and solubilized inorganic phosphorus. The bacterial strain A3 solubilized FePO4 (4 mg L−1) and Ca3(PO4)2 (50 mg L−1). P solubilization was assayed with glucose and sucrose as carbon sources for A3 (Bacillus pumilus MN100586). After four culture days, Ca3(PO4)2 was solubilized, reaching 246 mg L−1 with sucrose in culture media. Using glucose as a carbon source, FePO4 was solubilized and reached 282 mg L−1 in six culture days. Our findings were: Pseudomonas libanensis, and Bacillus siamensis, as new bacteria, can be reported as P solubilizers with tolerance to acidic or alkaline pH levels. The bacterial strain B. pumilus grew using two sources of inorganic phosphorus and carbon, and it tolerated pH changes. For that reason, it is an ideal candidate for inorganic phosphorus solubilization and future production as a biofertilizer.

Endophytic Bacillus vallismortis and Bacillus tequilensis bacteria isolated from medicinal plants enhance phosphorus acquisition and fortify Brassica napus L. vegetative growth and metabolic content

“…The pH of the culture medium used for phosphate solubilization decreased, which may be a sign of organic acids indirectly present. According to some reports, the PSB produces organic acids that cause the culture medium to become more acidic (Benbrik et al, 2020;Sanchez-Gonzalez et al, 2022), which is the primary microbial mechanism by which inorganic P is solubilized (Prabhu et al, 2019).…”

Managing Soil and Plant Nutrients: Role of Microbial Phosphate Solubilisation

“…Achromobacter xylosoxidans China [26] Acinetobacter calcoaceticus Iran [27] Advenella mimigardefordensis Spain [28] Arthrobacter luteolus Iran [27] Aspergillus awamori Indonesia [29] Aspergillus niger India, China [30,31] Aspergillus terreus Indonesia [29] Bacillus amyloliquefaciens Italy [32] Bacillus aryabhattai IA20 Pakistan [33] Bacillus cereus Spain, Iran [27,28] Bacillus cereus MZUTZ01 India [34] Bacillus firmus Pakistan [35] Bacillus licheniformis Pakistan [35] Bacillus megaterium China, Brazil, Spain, Thailand [28,[36][37][38][39] Bacillus mojavensis Thailand [36] Bacillus pumilus Mexico [37] Bacillus safensis Pakistan [35] Bacillus safensis IALR1035 USA [38] Phosphorus in Soils and Plants…”

“…Bacillus siamensis Mexico [37] Bacillus subtilis India, Indonesia, Brazil [29,34,39] Bacillus subtilis IA6 Pakistan [33] Bacillus subtilis IALR1033 USA [38] Bacillus thuringensis MZUTZ13 India [34] Burkholderia cenocepacia Indonesia [29] Burkholderia cepacia Indonesia [29] Burkholderia cepacia ISOP5 China [40] Burkholderia fungorum Spain [28] Burkholderia gladioli India [34] Burkholderia seminalis Indonesia [29] Burkholderia vietnamiensis Iran [27] Cellulosimicrobium cellulans China [26] Enterobacter bugandensis Morocco [41] Enterobacter cloacae C8 China [42] Enterobacter hormaechei(LMG 27195) China [43] Funneliformis mosseae China [44] Funneliformis mosseae BEG234 Italy [32] Geobacillus stearothermophillus MZUTZ08 India [34] Klebsiella variicola Brazil [45] Nocardiopsis alba Morocco [46,47] Novosphingobium barchaimii(LL02) China [43] Novosphingobium resinovorum China [42] Ochrobactrum haematophilum China [26] Ochrobactrum pseudogrignonense Brazil [45] Ochrobactrum pseudogrignonense(CCUG30717) China [43] Paenibacillus polymyxa IA7 Pakistan [33] Pantoea agglomerans Tunisia, Morocco [41,48] Pantoea agglomerans IALR1325 USA [38] Pantoea agglomerans p v. P 5 Iran [49] Pantoea ananatis Brazil [45] Pantoea roadsii(LMG26273) China [43] Pantoea stewartii subsp. Indologenes Morocco [41] Pantoea vagans IALR611 USA…”

“…Pseudomonas brassicacearum supsp. Neoaurantiaca Morocco [41] Pseudomonas cepaceae Egypt [52] Pseudomonas donghuensis(HYS) China [43] Pseudomonas fluorescens Tunisia [50] Pseudomonas grimontii(CFML97 514) China [43] Pseudomonas lactis Morocco [41] Pseudomonas libanensis Mexico [37] Pseudomonas mallei Egypt [52] Pseudomonas palleroniana India [51] Pseudomonas plecoglossicida C10 China [42] Pseudomonas proteolytica India [51] Pseudomonas psychrotolerans IALR632 USA [38] Pseudomonas putida pv. P13 Iran [49] Ralstonia pickettii C9 China [42] Rhizophagus irregularis BEG72 Italy [32] Rhodopseudomonas palustris ISP-1 China [40] Serratia rubidaea Morocco [41] Staphylococcus pastueri MZUTZ02 India [34] Stenotrophomonas maltophilia Tunisia, China [26,50] Streptomyces alboviridis Morocco [47] Streptomyces fulvissimus Morocco [46] Streptomyces griseorubens Morocco [46,47] Streptomyces microflavus Morocco [46] Streptomyces pratensis Morocco [46] Streptomyces youssoufiensis Morocco [46] Talaromyces minioluteus Iran [27] Talaromyces pinophilus Iran, Indonesia [27,29] Talaromyces stipitatus Iran [27] Trichoderma asperellum LZ1 China [53] Table 1.…”

Phosphate solubilization potential of PSB: An advance approach to enhance phosphorous availability for phytostimulation

“…The phosphate solubilizing index and efficiency of bacterial strains were analyzed using Pikovskaya (PVK) phosphate growth medium following Sanchez-Gonzalez et al (2022). To assess the solubilization of insoluble phosphorus, pure bacterial colonies from each strain were spot-inoculated onto plates and then incubated at 37°C for a period of seven days.…”