Isolation and Characterization of Urease-Producing Soil Bacteria

Efficacy of High-Altitude Biofilm-Forming Novel Bacillus subtilis Species as Plant Growth-Promoting Rhizobacteria on Zea mays L

With the global population explosion, the need for increasing crop productivity is reaching its peak. The significance of organic means of cultivation including biofertilizers and biopesticides is undeniable in this context. Over the last few decades, the use of rhizobacteria to induce crop productivity has gained particular interest of researchers. Of these, several Bacillus spp. have been known for their potential plant growth-promoting and phyto-pathogenic actions. Keeping this background in mind, this study was formulated with an aim to unravel the PGPR and phyto-pathogenic potency of Bacillus sp. isolated from extreme environmental conditions, viz. high-altitude waters of Ganges at Gangotri (Basin Extent Longitude Latitude-73° 2' to 89° 5' E 21° 6' to 31° 21' N). Based on recent studies showing the impact of biofilm on bacterial PGPR potency, three novel strains of Bacillus subtilis were isolated on basis of their extremely high biofilm-producing abilities (BRAM_G1: Accession Number MW006633; BRAM_G2: Accession Numbers MT998278-MT998280; BRAM_G3: Accession Number MT998617), and were tested for their PGPR properties like nutrient sequestration, growth hormone production (IAA, GA3), stress-responsive enzyme production (ACC deaminase) and lignocellulolytic and agriculturally important enzyme productions. The strains were further tested for the plethora of metabolites (liquid and VOCs) exuded by them. Finally, the strains both in individually and in an association, i.e. consortium was tested on a test crop, viz. Zea mays L., and the data were collected at regular intervals and the results were statistically analysed. In the present study, the role of high-altitude novel Bacillus subtilis strains as potent PGPR has been analysed statistically.

Biodiversity and biological applications of marine actinomycetes-Abu-Qir Bay, Mediterranean Sea, Egypt

BACKGROUND

The ability of actinomycetes to produce bioactive secondary metabolites makes them one of the most important prokaryotes. Marine actinomycetes are one of the most important secondary metabolites producers used for pharmaceuticals and other different industries.

RESULTS

In this study, the promising actinomycetes were isolated from Abu-Qir Bay. Four different media named as starch nitrate, starch casein, glycerol asparagine, and glycerol glycine were used as a preliminary experimental media to study the role of the medium components on the counts of actinomycetes in sediment samples. The results indicated that starch casein medium reported the highest counts (30-63 CFU/g) in all the tested sites. Lower counts were detected on starch nitrate and glycerol asparagine. On the other hand, glycerol glycine medium gave the lowest counts (15-48 CFU/g). Abu-Qir8 harbored the highest average count of actinomycetes (63 CFU/g), followed by Abu-Qir1 (48 CFU/g). The lower counts were detected in Abu-Qir5 and Abu-Qir7 (26 and 29 CFU/g, respectively). A total of 12 pure obtained actinomycetes isolates were subjected to morphological, physiological, and biochemical characterization. The selected actinobacterial isolates were subjected to numerical analysis, and the majority of isolates were grouped into four main clusters (A, B, C, & D), and each of them harbored two isolates; additionally, four isolates did not cluster at this similarity level. Isolate W4 was carefully chosen as the most promising pigment and antimicrobial agent's producer; the produced pigment was extracted and optimized by statistical experiments (PBD & BBD) and was tested for its anti-inflammatory activity. The results showed anti-inflammatory effect and prevented the denaturation of BSA protein at a concentration much higher than the safe dose and increased with increasing the pigment concentration.

CONCLUSION

Marine actinomycetes play a vital role in the production of novel and important economic metabolites that have many industrial and pharmaceuticals applications. Streptomyces genera are the most important actinomycetes that produce important metabolites as previously reported.

Bacillus cereus G2 Facilitates N Cycle in Soil, Further Improves N Uptake and Assimilation, and Accelerates Proline and Glycine Betaine Metabolisms of Glycyrrhiza uralensis Subjected to Salt Stress

Soil salinity is a severe abiotic stress that reduces crop productivity. Recently, there has been growing interest in the application of microbes, mainly plant-growth-promoting bacteria (PGPB), as inoculants for saline land restoration and plant salinity tolerance. Herein, the effects of the plant endophyte G2 on regulating soil N cycle, plant N uptake and assimilate pathways, proline and glycine betaine biosynthesis, and catabolic pathways were investigated in Glycyrrhiza uralensis exposed to salinity. The results indicated that G2 improved the efficiency of N absorption and assimilation of plants by facilitating soil N cycling. Then, G2 promoted the synthesis substrates of proline and glycine betaine and accelerated its synthesis rate, which increased the relative water content and reduced the electrolyte leakage, eventually protecting the membrane system caused by salt stress in G. uralensis. These findings will provide a new idea from soil to plant systems in a salinity environment.

Isolation and Evaluation of the Antagonistic Activity of Cnidium officinale Rhizosphere Bacteria against Phytopathogenic fungi (Fusarium solani)

Cnidium officinale Makino, a perennial crop in the Umbeliperae family, is one of Korea's representative forest medicinal plants. However, the growing area of C. officinale has been reduced by plant disease and soil sickness caused by fusarium wilt. This study isolated rhizosphere bacteria from C. officinale, and their antagonistic activity was evaluated against Fusarium solani. Particularly, four isolated strains, namely, PT1, ST7, ST8, and SP4, showed a significant antagonistic activity against F. solani. An in planta test showed that the mortality rates of shoots were significantly low in the PT1-inoculated group. The fresh and dry weights of the inoculated plants were also higher than that of the other groups. The 16S rRNA gene sequencing identified the strain PT1 as Leclercia adecarboxylata, and downstream studies confirmed the production of antagonism-related enzymes such as siderophore and N-acetyl-β-glucosaminidase. The phosphorous solubilizing ability and secretion of related enzymes were also analyzed. The results showed that PT1 strain could be utilized as promising plant growth-promoting rhizobacteria (PGPR) and biocontrol agents (BCAs).

The dependent correlation between soil multifunctionality and bacterial community across different farmland soils

Introduction

Microorganisms play a critical role in soil biogeochemical cycles, but it is still debated whether they influence soil biogeochemical processes through community composition and diversity or not. This study aims to investigate variation in bacterial community structure across different soils and its correlation to soil multifunctionality. Soil samples were collected from five typical farmland zones along distinct climatic gradients in China.

Methods

The high-throughput sequencing (Illumina MiSeq) of 16S rRNA genes was employed to analyze bacterial community composition in each soil sample. Multivariate analysis was used to determine the difference in soil properties, microbial community and functioning, and their interactions.

Results

Cluster and discrimination analysis indicated that bacterial community composition was similar in five tested soil samples, but bacterial richness combined with soil enzyme activities and potential nitrification rate (PNR) contributed most to the differentiations of soil samples. Mantel test analysis revealed that bacterial community composition and richness were more significantly shaped by soil nutrient conditions and edaphic variables than bacterial diversity. As for soil multifunctionality, soil microbial community level physiological profiles were little affected by abiotic and biotic factors, while soil enzymes and PNR were also significantly related to bacterial community composition and richness, in addition to soil N and P availability.

Conclusion

Cumulatively, soil enzymes' activities and PNR were greatly dependent on bacterial community composition and richness not diversity, which in turn were greatly modified by soil N and P availability. Therefore, in the future it should be considered for the role of fertilization in the modification of bacterial community and the consequent control of nutrient cycling in soil.

Effects of pharmaceuticals on the nitrogen cycle in water and soil: a review

The effects of pharmaceuticals on the nitrogen cycle in water and soil have recently become an increasingly important issue for environmental research. However, a few studies have investigated the direct effects of pharmaceuticals on the nitrogen cycle in water and soil. Pharmaceuticals can contribute to inhibition and stimulation of nitrogen cycle processes in the environment. Some pharmaceuticals have no observable effect on the nitrogen cycle in water and soil while others appeared to inhibit or stimulate for it. This review reports on the most recent evidence of effects of pharmaceuticals on the nitrogen cycle processes by examination of the potential impact of pharmaceuticals on nitrogen fixation, nitrification, ammonification, denitrification, and anammox. Research studies have identified pharmaceuticals that can either inhibit or stimulate nitrification, ammonification, denitrification, and anammox. Among these, amoxicillin, chlortetracycline, ciprofloxacin, clarithromycin, enrofloxacin, erythromycin, narasin, norfloxacin, and sulfamethazine had the most significant effects on nitrogen cycle processes. This review also clearly demonstrates that some nitrogen transformation processes such as nitrification show much higher sensitivity to the presence of pharmaceuticals than other nitrogen transformations or flows such as mineralization or ammonia volatilization. We conclude by suggesting that future studies take a more comprehensive approach to report on pharmaceuticals' impact on the nitrogen cycle process.