Category Technology

A group from Agricultural University of Athens, Athens, Greece, etc. has reported that the mixtures of Bacillus (1.SG.7, 5.SG.3) and Pseudomonas (2.SG.20, 2.C.19) strains in wheat rhizosphere enhanced the lateral roots abundance and shoots biomass of wheat, and mitigated salinity stress, comparing with the cases used independently.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8400701/

Sixty-eight arylsulfatase (ARS)-producing bacterias were isolated from the rhizosphere of durum wheat on calcareous soil. Phylogenetic analysis showed that most of the isolates belonged to the Pseudomonas and Bacillus genus. From view points of the following items, IAA production, antifungal activity, biofilm formation, and salinity tolerance, Bacterial Strains were selected from the isolated ARS-producing bacterias. Those were Bacillus (1.SG.7, 5.SG.3), Pseudomonas (2.SG.20, 2.C.19, 3.SG.19, 2.C.23, 4.SG.6, 2.SG.8)

All 8 bacterial strains enhanced the number of lateral roots and shoot biomass. The growth-promoting ability was enhanced by using strain mixtures, above all, mixtures of Bacillus (1.SG.7, 5.SG.3) and Pseudomonas (2.SG.20, 2.C.19) strains, enhanced the lateral roots abundance and shoots biomass, mitigated salinity stress.

Since the rhizosphere is a quite complex system including a number of bacterias and fungi, it must be a good way to focus on representative strains as shown here to understand how more effective rhizospheric consortium is formed as plant growth promoting rhizobacteria (PGPR).

A group from University of Colorado, Aurora, USA, etc. has reported that SARS-CoV-2 Lambda variant has higher infectivity than Delta variant.
https://pubmed.ncbi.nlm.nih.gov/34462744/

The binding affinity of overall antibodies from Pfizer-BioNTech vaccinated individuals droped dramatically (about 3.5 times fold drop for the Delta variant, and about 4.0times fold for the Lambda variant) after six months. These data suggest that the Lambda variant has a better chance than the Delta variant to escape the immunity built by the vaccination.

Although the mutations of L452Q and F490S in RBD of Lambda varient do not bring any enhance of the binding between RBD and ACE2 comparing with Delta variant, both mutations lead to the disruptions of a hydrophobic patch, which is a critical area for the binding of broadly neutralizing antibodies. This could be a reason why Lambda variant has higher infectivity than Delta variant.

A group from Benemérita Universidad Autónoma de Puebla (BUAP), Puebla, Pue., México, etc. has reported on pathogen inhibitory substances extracted rhizospheric bacteria, Pseudomonas protegens EMM-1.
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0240545

Pseudomonas protegens EMM-1 was isolated from the rhizosphere of red maize. It was found that P. protegens EMM-1 can efficiently inhibit the growth of a broad spectrum of bacteria, including Klebsiella sp. and Streptococcus sp.

To evaluate the inhibitory effect of secreted substances, First of all, conventional centrifugation methods for obtaining cell-free culture supernatants (CFSs) were used. However, CFSs from P. protegens EMM-1 did not show inhibitory activity. Instead of that, the inhibitory substances could be isolated from agar by the cold-leaching methodology using ethanol. The inhibitory substances displayed strong inhibitory activity as shown below, which suggests the existence of other inhibitory substances that could be explored in the future.

The molecular size of the inhibitory substances were estimated between 3 to 10 kDa. The inhibitory activity was completely lost at 100°C but remained stable between -4°C and 60°C. The inhibitory activity of the crude extract was stable within the pH range of 6 to 8.　In this paper, the molecular structures of those inhibitory substances were not identified unfortunately.

Anyway, this work demonstrated the significance of evaluating rhizospheric bacteria to discover inhibitory compounds that may potentially be used for the development of new antimicrobial therapies for application in medicine or agriculture.

A group from Monoclonal Antibody Discovery Lab, Fondazione Toscana Life Sciences, Siena, Italy, etc. has reported on SARS-CoV-2 escaped from neutralizing convalescent plasma in 80days by introducing mutations under the selective pressure of immunity.
https://www.pnas.org/content/118/36/e2103154118.long

An important question for vaccine development is whether the authentic virus, under the selective pressure of the polyclonal immune response in convalescent or vaccinated people, can evolve to fully escape immunity and antibody treatment. To address this question, authors co-incubated the authentic SARS-CoV-2 wild-type (WT) virus and a potent neutralizing plasma with Vero E6 cells for more than 14 passages and 90 days.

The plasma used in the co-incubation experiments was selected from 20 plasmas collected from COVID-19 convalescent patients between March and May 2020 where only the original Wuhan virus and D614G variant (SARS-CoV-2 WT and SARS-CoV-2 D614G variant) were circulating. The plasma (named PT188) showed the highest binding to the SARS-CoV-2 S1–S2 subunits and among the highest binding titers against the RBD (1/1,280).

The plasma fully neutralized the virus for seven passages, but, after seven passages and 45 days, the deletion of F140 in the spike N-terminal domain (NTD) N3 loop led to partial breakthrough. At 11 passages and 73 days, an E484K substitution in the receptor-binding domain (RBD) occurred, followed, at 12 passages and 80 days, by an insertion in the NTD N5 loop containing a new glycan, which generated a variant completely resistant to plasma neutralization.

Mutations with deletions in or near the NTD loops observed in this in vitro experiments were observed in the real world as recent SARS-CoV-2 variants (α、β、γ variants), and the introduction of a glycan is a well-known immunogenic escape strategy observed in a variety of viruses, such as influenza and HIV. Remarkably, the evolution of the E484K substitution observed in this in vitro experimental setting was also replicated in the real world by the emergence of E484K mutation in β and γ variants.

A group from International Centre for Genetic Engineering and Biotechnology, Trieste, Italy, etc. has reported on effects of Pseudomonas chlororaphis inoculation in Rice rhizosphere.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8309335/

Among the group of Plant Growth-Promoting Rhizobacteria (PGPR), strains belonging to the Pseudomonas chlororaphis species have been found in association with a wide range of plants, both mono- and dicotyledonous, and both wild and cultivated. P. chlororaphis is currently classified into four subspecies, namely chlororaphis, aureofaciens, aurantiaca, and piscium. Several strains of P. chlororaphis have shown potential for application as plant probiotics due to their rhizosphere colonization abilities and plant-associated beneficial phenotypes such as chemotaxis and motility, biofilm formation, P solubilization, aminocyclopropane-1-carboxylic acid (ACC) deaminase, Indole-3-acetic acid (IAA) production and biocontrol.

P. chlororaphis strains produce different antifungal compounds such as Prn (pyrrolnitrin), PCN (phenazine-1-carboxamide), PCA (phenazine-1-carboxylic acid), 2-OH-PHZ (2-hydroxyphenazine), HPR (2-hexyl-5-propyl-alkylresorcinol) and HCN (hydrogen cyanide). These molecules inhibit the growth of various phytopathogens belonging to the Fusarium group and different species of Colletotrichum, Phytophthora, Pythium, Sclerotinia, Magnaporthe oryzae and Rhizoctonia, protecting plants.

In order to determine the effects of P. chlororaphis on plant growth, several phenotypic parameters were assayed. Statistical analyses were carried out on chlorophyll, flavonoid content and nitrogen balance index (NBI) as physiological parameters. In addition, plant height and dry shoot biomass at 90 days post inoculation (dpi) were also established. Results did not show any statistical differences between control and P. chlororaphis inoculated plants, although a tendency on higher NBI and lower flavonoid contents was measured in inoculated plants compared with the control. It was concluded that under the conditions tested, no significant plant beneficial effect was observed upon seed inoculation of P. chlororaphis.

However, there was a possibility that the plant defense system could be primed by P. chlororaphis maintaining a low level of stress.
In P. chlororaphis inoculated plants, it was found that expression of genes associated with defense OsISAP1, encoding for a multiple stress-responsive zinc-finger protein, was up-regulated at 28 dpi, suggesting an activation of the plant defense mechanisms.

A group from University of Medicine “Aldo Moro”, Bari, Italy, etc. has reported on prognostic power of Galectin-3 against severe COVID-19.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8332745/

This is the first study in scientific literature assessing the prognostic role of Galectin-3 in acute respiratory failure secondary to COVID-19 disease. Patients with higher serum levels of Galectin-3 tend to develop a more severe degree of ARDS with a worse prognosis. It is well known that SARS-COV2 infection can lead to the so called “cytokine storm” in some susceptible patients. For instance, our non-survivors group shows increased blood levels of various inflammation markers, which are frequently associated with negative outcomes in COVID-19 disease. Nevertheless, only IL-6, CRP and Galectin-3 remain statistically significant in our multivariate regression model. This finding is not surprising for IL-6 and CRP, which were previously reported as important prognostic markers in COVID-19 disease. On the contrary, this is the first study addressing this role for Galectin-3. Furthermore, among the explored parameters, Galectin-3 shows the best AUC curve in ROC analysis, showing good diagnostic power for severe ARDS (AUC 0.75, p = 0.001) using a cut-off value of 35.3 ng/ml.

In fact, patients with Galectin-3 serum levels above 35.3 ng/ml were not only more prone to develop severe ARDS, but also markedly at higher risk of ICU admission or death. The cohort size of this study was 156 patients.

A group from University of Hertfordshire, Hatfield, UK has reported that Bacillus amyloliquefaciens inoculation singularly increased winter wheat crop biomass and arbuscular mycorrhizal (AM) fungal symbiosis.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8309287/

Microbial associations between plant and soil are highly complex and provide a myriad of interactions with a wide range of plant and soil benefits including increased soil fertility and aggregation, improved plant immunity and defence, increased plant biomass and carbon sequestration. Arbuscular mycorrhizal (AM) fungi are one of the constituent organisms within the rhizosphere of an estimated 80% of terrestrial plants forming mutualistic biotrophic symbiosis with host plants. Mycorrhizal helper bacteria (MHB) stimulate mycorrhizae formation and further enhance plant-fungi symbiosis. The role of MHB and their interaction with AM fungi is poorly understood as is the extent of the tripartite rhizobacteria-AM fungi-host plant relationship. As MHBs, three Gram-positive Bacilli species were used in addition to (Ri) AM fungus R. intraradices in this experiment: (Bs) B. subtilis, (Bp) B. pumilis, and (Ba) B. amyloliquefaciens.

Soil cultivation by conventional tillage (CT) has been shown to directly influence the abundance and diversity of the soil microbiome. The hyphal networks of AM fungi are damaged by CT resulting in decreased root cortical arbuscules. However, the impact of tillage on rhizobacteria is relatively unknown. So, a series of experiments was done under two tillage regimes, CT and zero tillage (ZT).

As a conclusion, it was found that B. amyloliquefaciens (Gram-positive Bacilli) applied singularly increased winter wheat crop biomass and AM fungal symbiosis.