Division of Basic Science and Humanities, Faculty of Agriculture, Sher-e-Kashmir University of Agricultural Sciences and Technology, Sopore 193201, India.
Division of Agronomy, Faculty of Agriculture, Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir, Sopore 193201, India.
Molecules. 2021 Sep 23;26(19):5758. doi: 10.3390/molecules26195758.
Soil potassium (K) supplement depends intensively on the application of chemical fertilizers, which have substantial harmful environmental effects. However, some bacteria can act as inoculants by converting unavailable and insoluble K forms into plant-accessible forms. Such bacteria are an eco-friendly approach for enhancing plant K absorption and consequently reducing utilization of chemical fertilization. Therefore, the present research was undertaken to isolate, screen, and characterize the K solubilizing bacteria (KSB) from the rhizosphere soils of northern India. Overall, 110 strains were isolated, but only 13 isolates showed significant K solubilizing ability by forming a halo zone on solid media. They were further screened for K solubilizing activity at 0 °C, 1 °C, 3 °C, 5 °C, 7 °C, 15 °C, and 20 °C for 5, 10, and 20 days. All the bacterial isolates showed mineral K solubilization activity at these different temperatures. However, the content of K solubilization increased with the upsurge in temperature and period of incubation. The isolate KSB (Grz) showed the highest K solubilization index of 462.28% after 48 h of incubation at 20 °C. The maximum of 23.38 µg K/mL broth was solubilized by the isolate KSB (Grz) at 20 °C after 20 days of incubation. Based on morphological, biochemical, and molecular characterization (through the 16S rDNA approach), the isolate KSB (Grz) was identified as sp. The majority of the strains produced HCN and ammonia. The maximum indole acetic acid (IAA) (31.54 µM/mL) and cellulase (390 µM/mL) were produced by the isolate KSB (Grz). In contrast, the highest protease (525.12 µM/mL) and chitinase (5.20 µM/mL) activities were shown by standard strain and KSB (Gmr) isolate, respectively.
土壤钾（K）补充主要依赖于化肥的施用，而化肥对环境有很大的危害。然而，一些细菌可以作为接种剂，将不可用和不溶性的 K 形式转化为植物可利用的形式。这种细菌是一种环保的方法，可以增强植物对 K 的吸收，从而减少对化肥的利用。因此，本研究从印度北部根际土壤中分离、筛选和鉴定了溶钾细菌（KSB）。总共分离出 110 株，但只有 13 株在固体培养基上形成晕圈，表现出显著的溶钾能力。进一步筛选在 0°C、1°C、3°C、5°C、7°C、15°C 和 20°C 下培养 5、10 和 20 天的溶钾活性。所有细菌分离株在不同温度下均表现出矿物 K 的溶出活性。然而，溶钾含量随着温度和培养时间的增加而增加。在 20°C 下培养 48 小时后，分离株 KSB（Grz）的溶钾指数最高，为 462.28%。在 20°C 下培养 20 天后，分离株 KSB（Grz）可溶出最大量的 23.38µg K/mL 肉汤。根据形态学、生物化学和分子特征（通过 16S rDNA 方法），分离株 KSB（Grz）被鉴定为 sp. 大多数菌株产生 HCN 和氨。分离株 KSB（Grz）产生的吲哚乙酸（IAA）最大量为 31.54µM/mL，纤维素酶最大量为 390µM/mL。相反，标准菌株 和 KSB（Gmr）分离株分别显示出最高的蛋白酶（525.12µM/mL）和几丁质酶（5.20µM/mL）活性。
