Psychrotolerant Mesorhizobium sp. Isolated from Temperate and Cold Desert Regions Solubilizes Potassium and Produces Multiple Plant Growth Promoting Metabolites

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 Mesorhizobium 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 Bacillus mucilaginosus and KSB (Gmr) isolate, respectively.

Use of probiotics for formation of microflora of gastrointestinal tract of calves

The results of the use of probiotic strains of microorganisms of the Bacillus family for the correction and formation of the microflora of the gastrointestinal tract and the impact on metabolism in calves are presented. The aim of the study. To analyze the effect of probiotics on the microflora of the gastrointestinal tract in calves and biochemical parameters of blood in calves up to one month. Materials and methods. The research was conducted during 2020 in the conditions of Ukrainian farms for cattle breeding. Five experimental groups of five one-week-old calves were formed in each and one control group. Calves were kept separately in the same conditions on the same diet, but with feeding together with colostrum substitute probiotics of five grams per animal: Bacillus amyloliquefaciense, Bacillus mucilaginosus, Bacillus coagulans, Bacillus megaterium, Bacillus pumilus. The strains are deposited and produced by “Kronos Agro” Ukraine. Results. It was found that as a result of studies when feeding calves B. coagulans, B. pumilus and B. mucilaginosus the number of Lactobacillus sp. was 80 % higher than in the control group. The level of opportunistic pathogens in the experimental group with B. coagulans had minimal values. Animals in the group where B. mucilaginosus was given had a higher amount of Candida - up to 300 CFU/g and Enterobacteriaceae – 200 CFU/g; which is 50 % less compared to control groups, but more than in the experiment with B. coagulans. According to the results of biochemical examination of blood serum in calves, the absence of toxic effects of probiotic strains: Bacillus amyloliquefaciense, Bacillus mucilaginosus, Bacillus coagulans, Bacillus megaterium, Bacillus pumilus on the internal organs of animals was established. Conclusions. It was found that the maximum positive effect on the microflora of the gastrointestinal tract of calves up to 30 days of age had B. coagulans (1×109) when fed at a dose of 5 g per animal. The amount of Lactobacillus sp. was the maximum and reached 800 CFU/g, which is 80 % more than in the control group. At the same time, the level of opportunistic pathogens in the experimental group with B. coagulans had minimal indicators and was: Clostridium by 20 %, Escherichia coli – by 70 %, Enterobacteriaceae, Staphylococcus and Candida – 100 % less than the control. In the study of biochemical parameters, it was found that the activity of enzymes, protein and glucose levels in the serum of experimental animals fed with B. coagulans were within the physiological norm, indicating a normal metabolic process and no toxic effects.

Optimization of onion production technology under annual growing in Non-Chernozem zone

Сегодня лук-репка занимает в стране третье место по площади возделывания среди овощных культур при средней урожайности в 2019 году 27,8 т/га. Потенциал современных сортов и гибридов составляет 100 – 120 т/га. В условиях Нечерноземья проблема поражения лука пероноспорозом наиболее злободневна. Цель исследований – оптимизация элементов технологии производства лука-репки в однолетней культуре (предпосевная обработка семян смесью ризосферных ассоциативных бактерий, нормы и сроки внесения бактерий совместно с минеральными удобрениями, нормы и сроки внесения фунгицидов), обеспечивающих урожайность 70–80 т/га на аллювиальных луговых почвах Нечерноземной зоны. Полевые опыты были проведены на опытном поле ВНИИО согласно стандартных методик. Почва участка аллювиальная луговая среднесуглинистая. Содержание гумуса в слое 0-20 см составляет 3,0–3,2%, pН солевой вытяжки колеблется в значительных пределах 5,0-6,5. Содержание суммы поглощенных оснований 45,0 мг-экв. на 100 г почвы. Содержание Р2О5 – 22,0 мг на 100 г почвы (по Чирикову), калия – 15,2 мг (по Масловой), общего азота — 6,0 мг. В 2018 – 2020 годах было установлено, что: обработка семян лука смесью микробиологических препаратов ризосферных ассоциативных бактерий Экстрасол (штамм Bacillus subtilis Ч-13), Азотовит (штамм Azotobakter chroococcum) и Фосфатовит (штамм Bacillus mucilaginosus) дозами, согласно рекомендаций производителей, не показала достоверного увеличения полевой всхожести испытанных вариантов по отношению к контролю. Внесение смеси ризосферных ассоциативных бактерий препаратов БисолбиСан (штамм Bacillus subtilis Ч-13), Азотовит (штамм Azotobakter chroococcum) и Фосфатовит (штамм Bacillus mucilaginosus) суммарными дозами, л/га: 20,0; 60,0; 70,0;80,0; 90,0; совместно с минеральными подкормками на луке в однолетней культуре обеспечивает значительную (до 20%) прибавку урожайности. Сроки и нормы внесения препаратов требуют дальнейшей оптимизации. Имеет место усиление иммунитета растений против пероноспороза при некорневых обработках фунгицидами Ридомил Голд МЦ и Метаксил совместно с бактериальным препаратом БисолбиСан (штамм Bacillus subtilis Ч-13) в 1% концентрации рабочего раствора. Интервалы обработок 7 – 10 дней фунгицидами Ридомил Голд МЦ и Ревус Топ (на луке не зарегистрирован) следует считать оптимальными против пероноспороза. Currently, the onion-turnip occupies the third place in the country in terms of cultivation area among vegetable crops with an average yield of 27.8 t/ha in 2019 year. The potential of modern sorts and hybrids is 100-120 t/ha. In the conditions of Non-Chernozem zone, the problem of onion disease with peronosporosis is the most urgent. The aim of the research is to optimize the elements of the onion – turnip production technology in an annual crop (pre-sowing seeds treatment with a mixture of rhizospheric associative bacteria, norms and terms of application of bacteria together with mineral fertilizers, norms and terms of application of fungicides), providing a yield of 70-80 t/ha on alluvial meadow soils of the Non-Chernozem zone. Field experiments were conducted at the ARRIVG experimental field according to standard methods. The soil of the site is alluvial meadow medium loamy. The humus content in the 0-20 cm layer is 3.0 — 3.2%, pH of the salt extract varies in the significant range of 5.0-6.5. The content of the sum of absorbed bases is 45.0 mg-eq. per 100 g of soil. The content of P2O5 is 22.0 mg per 100 grams of soil (according to Chirikov), potassium –15.2 mg (according to Maslova), total nitrogen-6.0 mg. In 2018 – 20 years it was found that: Treatment of seeds onion mixture of microbiological preparations associative rhizosphere bacteria Extrasol (strain Bacillus subtilisCH-13), Azotovit (strain Azotobakter chroococcum) and Fosfatovit (strain Bacillus mucilaginosus) doses, according to the manufacturer's recommendations, did not show a significant increase in germination tested options with respect to the control; Introduction of a mixture of rhizospheric associative bacteria preparations BisolbiSan (Bacillus subtilis strain CH-13), Azotovit (Azotobakter chroococcum strain) and Fosfatovit (Bacillus mucilaginosus strain) in total doses, l/ha: 20,0; 60,0; 70,0;80,0; 90,0; together with mineral fertilizing on the onion in an annual crop, it provides a significant (up to 20%) increase in yield. The terms and rates of application of drugs require further optimization. There is an increase in the immunity of plants against peronosporosis during non-root treatments with fungicides Ridomil Gold MC and Metaxil together with the bacterial preparation BisolbiSan (Bacillus subtilis strain CH-13) in 1% concentration of the working solution. Treatment intervals of 7-10 days with the fungicides Ridomil Gold MC and Revus Top (not registered on the onion) should be considered optimal against peronosporosis.

Biomineralization Performance of Bacillus sphaericus under the Action of Bacillus mucilaginosus

Microbial Induced Calcite Precipitation (MICP) is a biochemical process widely found in nature, also known as microbial mineralization. This paper investigates whether this process can help promote the intelligent reinforcement and repair of underground projects such as mines and tunnels. We selected Bacillus sphaericus and Bacillus mucilaginosus as the research objects. The former has an outstanding urease production ability, and the latter can secrete carbonic anhydrase in vitro. Bacillus mucilaginosus was introduced into the culture solution of Bacillus sphaericus in the most suitable culture environment, and the changes of mineralization rate and mineralization yield of Bacillus sphaericus were observed and analyzed. The results revealed that, to maintain the highest growth rate of Bacillus sphaericus, the optimal pH value was between 7 and 8, the optimal urea concentration was 0.5 mol/L, the optimal Ca2+ concentration was 0.6 mol/L, and the optimal Luria-Bertani (LB) culture concentration was 20 g/L. The amount of biomineralized calcium carbonate precipitated in the double bacteria solution can reach 1.89 times the amount of the precipitation in the Bacillus sphaericus solution under the same conditions. It concludes that the introduction of Bacillus mucilaginosus can effectively increase the mineralization yield of Bacillus sphaericus without affecting the mineralized products.