A group from Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China, etch. has reported that Nguyenibacter sp. L1 is a good phosphate-solubilizing bacteria (PSB) in acid soil.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8637293/
Phosphorus (P) is an essential macronutrient required for plant growth and productivity. Even in P-rich soils, more than 80% of P is immobile and not readily accessible for plant uptake. P exists in soil in different forms, mainly as inorganic and organic P, whose proportions are soil dependent. The forms of inorganic P also vary in soil as the function of soil pH. In alkaline soils, inorganic P exists mainly in the form of calcium phosphate, magnesium phosphate, and octacalcium phosphate, and in acid soils with high level of weathering, iron (Fe) and aluminum (Al) oxides strongly absorb P to form fixed Fe-P and Al-P.
One of the promising ways to improve plant utilization of fixed P in soil will be increasing the bioavailability of insoluble P by improving soil, such as by inoculating or enhancing PSBs in soil.
In this study, a PSB strain with Al-P solubilizing activity, Nguyenibacter sp. L1, from the rhizosphere soil of L. bicolor grown in acid soils was isolated. The solubilization of Al-P by Nguyenibacter sp. L1 is associated with the secretion of gluconic acid in the presence of glucose as a carbon source. Gluconic acid can also alleviate Al toxicity to plants.
A large amount of gluconic acid and a higher available P concentration were observed in culture medium containing glucose as the carbon source and inoculated with Nguyenibacter sp. L1.
Then, to examine whether gluconic acid is able to detoxify Al, we compared the inhibitory effect of Al on the root elongation of rice plants in the presence or absence of gluconic acid. Rice root elongation was markedly inhibited by 50 μM Al with or without 0.05 mM gluconic acid, but this inhibitory effect disappeared in the presence of 0.5, 2.5, or 7.6 mM gluconic acid. This result indicates that the external addition of gluconic acid alleviated Al toxicity to plant roots.