Auswahl der wissenschaftlichen Literatur zum Thema „Stenotrophomonas rhizophila“

Activities of Stenotrophomonas rhizophila and Trichoderma sp. in Inhibiting the Growth of Ganoderma boninense ABSTRACTBasal stem rot (BSR) disease in oil palm (Elaeis guineensis Jacq.) due to infection of Ganoderma boninense. Various efforts to overcome BSR disease has been done, such as by utilizing endophytic microbes. The purpose of this research was to determine the activities of Stenotrophomonas rhizophila and Trichoderma sp inhibiting the growth of G. boninense. This research was divided into three stages, namely: stability test of S. rhizophila activity against G. boninense; activity of chitinase and cellulase enzymes produced by S. rhizophila; the effectiveness of S. rhizophila and Trichoderma sp. on G. boninense in a greenhouse. The parameters observed were plant height, leaves number, chlorophyll content, disease incidence and severity. The stability testing of S. rhizophila activity against G. boninense showed 53% of inhibition. Chitinase activity showed negative result. While cellulase index was about 0.46. The effectiveness test showed the significantly different results on plant height, leaves number and chlorophyll content.Keywords: Chitinase, cellulase, Ganoderma boninense, Stenotrophomonas rhizophila, Trichoderma sp. ABSTRAKPenyakit busuk pangkal batang (BPB) pada tanaman kelapa sawit (Elaeis guineensis Jacq.) muncul karena diinfeksi oleh Ganoderma boninense. Berbagai upaya penanggulangan penyakit BPB telah dilakukan, diantaranya dengan memanfaatkan mikroba endofit. Tujuan dari penelitian ini adalah untuk mengetahui aktivitas bakteri Stenotrophomonas rhizophila dan Trichoderma sp. dalam menghambat pertumbuhan G. boninense. Penelitian ini dibagi menjadi tiga tahapan, yaitu: pengujian stabilitas aktivitas S. rhizophila terhadap G. boninense; pengujian aktivitas enzim kitinase dan selulase yang dihasilkan oleh S. rhizophila; pengujian efektivitas S. rhizophila dan Trichoderma sp. terhadap G. boninense di rumah kaca. Parameter yang diamati pada pengujian efektivitas berupa tinggi tanaman, jumlah daun, jumlah klorofil, kejadian dan keparahan penyakit. Uji stabilitas aktivitas S. rhizophila terhadap G. boninense menunjukkan adanya penghambatan rata-rata sebesar 53%. Uji aktivitas enzim kitinase pada bakteri S. rhizophila menunjukkan hasil negatif. Sedangkan indeks enzim selulase pada bakteri S. rhizophila sebesar 0.46. Pada uji efektivitas tampak hasil yang berbeda nyata pada parameter tinggi tanaman, jumlah daun dan kandungan klorofil.Kata Kunci: Kitinase, selulase, Ganoderma boninense, Stenotrophomonas rhizophila, Trichoderma sp.

Although Stenotrophomonas maltophilia strains are efficient biocontrol agents, their field applications have raised concerns due to their possible threat to human health. The non-pathogenic Stenotrophomonas rhizophila species, which is closely related to S. maltophilia, has been proposed as an alternative. However, knowledge regarding the genetics of S. rhizophila is limited. Thus, the aim of the study was to define any genetic differences between the species and to characterise their ability to promote the growth of plant hosts as well as to enhance phytoremediation efficiency. We compared 37 strains that belong to both species using the tools of comparative genomics and identified 96 genetic features that are unique to S. maltophilia (e.g., chitin-binding protein, mechanosensitive channels of small conductance and KGG repeat-containing stress-induced protein) and 59 that are unique to S. rhizophila (e.g., glucosylglycerol-phosphate synthase, cold shock protein with the DUF1294 domain, and pteridine-dependent dioxygenase-like protein). The strains from both species have a high potential for biocontrol, which is mainly related to the production of keratinases (KerSMD and KerSMF), proteinases and chitinases. Plant growth promotion traits are attributed to the biosynthesis of siderophores, spermidine, osmoprotectants such as trehalose and glucosylglycerol, which is unique to S. rhizophila. In eight out of 37 analysed strains, the genes that are required to degrade protocatechuate were present. While our results show genetic differences between the two species, they had a similar growth promotion potential. Considering the information above, S. rhizophila constitutes a promising alternative for S. maltophilia for use in agricultural biotechnology.

The study was conducted at the Postharvest and Plant Biotechnology Laboratory, Department of Horticulture, Patuakhali Science and Technology University, Patuakhali, Bangladesh during the period from July to December 2018 to study the biocontrol performance of selected antagonistic bacteria Stenotrophomonas rhizophila strain PSTU-Hort-14 on BARI Aam-3. All the treatments were arranged in a completely randomized design (CRD) with five replications and repeated twice. The bacterial strain PSTU-Hort-14 was found highly compatible with 20% lemongrass extract and 2% sodium bicarbonate (SBC) or mixture of both which reduced 96.5% of the disease over control in naturally infected fruits at the end of 14 days of storage at 12±1ºC and 90±5% RH. The combined treatments of Stenotrophomonas rhizophila-lemongrass extract-SBC showed reduced weight loss by more than 25% compared to the control at 12±1ºC and 90±5% RH. The shelf life was thus extended by 15 days compared to control at 12±1ºC and 90±5% RH. Finally, it was clear that the strain Stenotrophomonas rhizophila strain PSTU-Hort-14 was effective when incorporated with 2% SBC and 20% lemongrass extract to control C. gloeosporioides as well as improve the postharvest quality of BARI Aam-3 during cold storage. Bangladesh J. Agri. 2023, 48(2): 13-29

In 2002, Wolf described a new species of Stenotrophomonas, Stenotrophomonas rhizophila, which is a non-pathogenic plant inhabitant. The defining characteristics of the new species, in contrast to S. maltophilia, were the following: growth at 4 °C, but its absence at 37 °C; the use of xylose as a carbon source; low osmolytic tolerance. S. rhizophila is isolated exclusively from the rhizosphere or from the internal tissues of plants, in particular from the vascular tissues of the root and stem. In 2014, a number of authors, studying cultivated heterotrophic bacteria and yeasts, which dominate in plant samples collected from various terrestrial biotopes near the Ukrainian Antarctic station on Galindez Island in Marine Antarctica, isolated a number of bacterial isolates. The authors’ phylogenetic analysis using only BLAST analysis made it possible to determine the approximate phylogenetic affiliation of the bacterial isolate to the family Gammaproteobacteria (genus Stenotrophomonas, species S. rhizophila). It is known that many processes that determine the biological features of microorganisms, the nature of their relationships between them, as well as micro- and macroorganisms in biocenoses, are carried out with the participation of the surface structures of the bacterial cell, which are in direct contact with the environment. Among them, of particular interest are lipopolysaccharides (LPS), components of the outer membrane of Gram-negative bacteria. However, to date, we have not found any works devoted to the study of S. rhizophila lipopolysaccharides in the literature available to us. The aim of the work was to clarify the phylogenetic position of the 6p5m bacterial strain isolated from the Antarctic region by constructing dendrograms, to study some of its phenotypic properties, to isolate lipopolysaccharides and study chemical and component composition, serological, and biological properties. Methods. Identification was carried out via ribosomal phylogeny. A fragment of the 16S rRNA gene of bacterial strain 6p5m was amplified by PCR using primers 8F and 1492R. The phylogenetic position of the strains was determined by construction of dendrograms, which show the position of the investigated strains among closely related and typical species and type species (programs ClustalX 2.1, Mega v. 6.00). LPS was obtained from cells by water-phenol extraction, electrophoresis was carried out in polyacrylamide gel, monosaccharide and fatty acid composition was determined by chromato-mass spectrometry, antigenic activity was studied by immunodiffusion in agar. Results. Phylogenetic analysis of the nucleotide sequence of the 16S rRNA gene revealed a high level of homology (99.8%) of the bacterial strain 6p5m with typical strain S. rhizophila DSM 14405T from the GenBank database, which allows us to classify it. Comparing phylogenetic analysis with phenotypic data, we can assert that strain 6p5m belongs to the S. rhizophila species. When studying the biopolymer composition of LPS by specific reactions to each component, it was found that the carbohydrate content was relatively low and amounted to 27.42% and 13.34% for LPS1 and LPS2, respectively. The content of characteristic LPS components: heptose and 2-keto-3-deoxyoctonic (KDO) acid was 1.78% and 0.034%, as well as 5.38% and 0.09%, respectively, for LPS1 and LPS2. Analysis of the monosaccharide composition of LPS preparations showed that fucose (72.57%) is present as a dominant monosaccharide in LPS1 and rhamnose (65.04%) in LPS2. The main monosaccharides of the extracellular component were galactose (39.92%) and rhamnose (24.36%). Analysis of the lipid part of the studied LPS indicates significant differences between them. In the composition of lipid A LPS1 and LPS2 of S. rhizophila 6p5m, anti-iso-pentadecanoic acid (a-i-C15:0) was predominant (25.58% and 39.24%, respectively), and 3-hydroxydodecanoic acid (3-OH-C12:0) in LPS2 (26.21%), hexadecanoic acid (С16:0) (27.06% and 10.51%, respectively) for LPS1 and LPS2. Cyclic acids were present only in LPS1, while i-C15:0 and 9-C16:1 only in LPS2. Electrophoretic analysis showed heterogeneity characteristic of an LPS molecule, manifested by a plurality of bands in the form of a «ladder» when the gel was stained with silver ions, which is associated with the presence in the composition of LPS preparations of O-specific polysaccharide structures with different lengths of oligosaccharide chains, which determine their different molecular weight. On the electropherogram of LPS1 and LPS2, bands were not visualized in the upper part of the electrophoretic track, which indicates the absence of S-forms of LPS with long O-specific chains, but a significant predominance of SR-form molecules in the membrane LPS pool. S. rhizophila 6p5m LPS showed significantly higher pyrogenic activity compared to pyrogenal, a pharmaceutical preparation, an active ingredient of which is Shigella typhi LPS. The extracellular polymer did not exhibit pyrogenic activity. In the double immunodiffusion reaction in agar according to Ouchterlony, it was found that the studied LPSs in the homologous system exhibit antigen activity. The antigens present in both LPS1and LPS2 and the extracellular component are identical: the antigen present in each of the wells binds to all antibodies that can interact with the antigen from the other well. It was shown that pre-sowing treatment of seeds with LPS preparations of S. rhizophila 6p5m stimulates the energy of seed germination. LPS1 (+2.82 cm) showed the greatest impact in comparison with the control. A significant stimulatory effect of LPS1, LPS2, and extracellular polymer was observed when studying their effects on mustard seedlings. Conclusions. The taxonomic position of bacterial strain 6r5m of the ecosystems of the polar region (Antarctica) was determined via the phylogenetic analysis taking into account the phenotypic features of the strain. The bacterial strain is represented in the phylum Proteobacteria, class Gammaproteobacteria, family Xanthomonadaceae, genus Stenotrophomonas, species S. rhizophila. From S. rhizophila cells, LPS preparations were obtained, which differed in monosaccharide and fatty acid composition, but showed high pyrogenicity. S. rhizophila represents a promising alternative to S. maltophilia for applications in agricultural biotechnology and biological control due to its ability to both stimulate plant growth and protect roots from biotic and abiotic stresses.

A Gram-negative, rod-shaped, non-spore-forming and nitrogen-fixing bacterium, designated ICB 89T, was isolated from stems of a Brazilian sugar cane variety widely used in organic farming. 16S rRNA gene sequence analysis revealed that strain ICB 89T belonged to the genus Stenotrophomonas and was most closely related to Stenotrophomonas maltophilia LMG 958T, Stenotrophomonas rhizophila LMG 22075T, Stenotrophomonas nitritireducens L2T, [Pseudomonas] geniculata ATCC 19374T, [Pseudomonas] hibiscicola ATCC 19867T and [Pseudomonas] beteli ATCC 19861T. DNA–DNA hybridization together with chemotaxonomic data and biochemical characteristics allowed the differentiation of strain ICB 89T from its nearest phylogenetic neighbours. Therefore, strain ICB 89T represents a novel species, for which the name Stenotrophomonas pavanii sp. nov. is proposed. The type strain is ICB 89T ( = CBMAI 564T = LMG 25348T).

In the present study, the following was investigated: (a) The effect of ulvan on in vivo and in vitro biocontrol of Debaryomyces hansenii and Stenotrophomonas rhizophila against Fusarium proliferaum and (b) the effect of ulvan on in vivo and in vitro growth of D. hansenii and S. rhizophila and muskmelon quality parameters. The results showed that the biocontrol activity of D. hansenii and S. rhizophila could be enhanced by ulvan (5 g/L). The combination of ulvan and S. rhizophila resulted in a more effective control of fruit rot in comparison to fungicide benomyl. On in vitro growth of F. proliferatum, individual treatments of D. hansenii and S. rhizophila inhibited spore germination and mycelial growth with no statistical difference with the combined treatments. Ulvan does not have a direct effect on the in vivo and in vitro growth of D. hansenii and S. rhizophila. Furthermore, the combined treatments improve the natural disease incidence and quality parameters like weight, firmness, total soluble solids (TSS), and pH. These results suggest that the use of ulvan may be an effective method to improve the biological activity of D. hansenii and S. rhizophila.

The indiscriminate use of synthetic fungicides has led to negative impact to human health and to the environment. Thus, we investigated the effects of postharvest biocontrol treatment with Debaryomyces hansenii, Stenotrophomonas rhizophila, and a polysaccharide ulvan on fruit rot disease, storability, and antioxidant enzyme activity in muskmelon (Cucumis melo L. var. reticulatus). Each fruit was treated with (1) 1 × 106 cells mL−1 of D. hansenii, (2) 1 × 108 CFU mL−1 of S. rhizophila, (3) 5 g L−1 of ulvan, (4) 1 × 106 cells mL−1 of D. hansenii + 1 × 108 CFU mL−1 of S. rhizophila, (5) 1 × 108 CFU mL−1 of S. rhizophila + 5 g L−1 of ulvan, (6) 1 × 106 cells mL−1 of D. hansenii + 1 × 108 CFU mL−1 of S. rhizophila + 5 g L−1 of ulvan, (7) 1000 ppm of benomyl or sterile water (control). The fruits were air-dried for 2 h, and stored at 27 °C ± 1 °C and 85–90% relative humidity. The fruit rot disease was determined by estimating the disease incidence (%) and lesion diameter (mm), and the adhesion capacity of the biocontrol agents was observed via electron microscopy. Phytopathogen inoculation time before and after adding biocontrol agents were also recorded. Furthermore, the storability quality, weight loss (%), firmness (N), total soluble solids (%), and pH were quantified. The antioxidant enzymes including catalase, peroxidase, superoxide dismutase, and phenylalanine ammonium lyase were determined. In conclusion, the mixed treatment containing D. hansenii, S. rhizophila, and ulvan delayed fruit rot disease, preserved fruit quality, and increased antioxidant activity. The combined treatment is a promising and effective biological control method to promote the shelf life of harvested muskmelon.

ABSTRACT The rhizobacterium Stenotrophomonas rhizophila accumulates the compatible solutes glucosylglycerol (GG) and trehalose under salt stress conditions. The complete gene for the GG synthesis enzyme was cloned and sequenced. This enzyme from S. rhizophila represented a novel fusion protein composed of a putative C-terminal GG-phosphate synthase domain and an N-terminal putative GG-phosphate phosphatase domain, which was named GgpPS. A similar gene was cloned from Pseudomonas sp. strain OA146. The ggpPS gene was induced after a salt shock in S. rhizophila cells. After the salt-loaded cells reached stationary phase, the ggpPS mRNA content returned to the low level characteristic of the control cells, and GG was released into the medium. The complete ggpPS gene and a truncated version devoid of the phosphatase part were obtained as recombinant proteins. Enzyme activity tests revealed the expected abilities of the full-length protein to synthesize GG and the truncated GgpPS to synthesize GG-phosphate. However, dephosphorylation of GG-phosphate was detected only with the complete GgpPS protein. These enzyme activities were confirmed by complementation experiments using defined GG-defective mutants of the cyanobacterium Synechocystis sp. strain PCC 6803. Genes coding for proteins very similar to the newly identified fusion protein GgpPS for GG synthesis in S. rhizophila were found in genome sequences of related bacteria, where these genes are often linked to a gene coding for a transporter of the Mfs superfamily.

Les graines constituent la source d’inoculum initiale pour le microbiote des plantes. Lors de la germination, le relargage d’exsudats à proximité des graines déclenche une intense compétition microbienne qui joue un rôle moteur dans l’assemblage du microbiote des plantes. Ce travail de thèse vise à explorer le rôle de la compétition d'interférence médiée par le système de sécrétion de type VI (T6SS). Le T6SS d’une souche de Stenotrophomonas rhizophila, une espèce bactérienne transmise efficacement aux plantules, a été utilisé comme modèle d’étude. Ce T6SS est impliqué dans l’inhibition de la croissance de nombreuses espèces bactériennes in vitro, dont la souche phytopathogène Xanthomonas campestris pv. campestris 8004 (Xcc8004). Cette inhibition de croissance bactérienne est corrélée à la proximité phylogénétique et métabolique entre S. rhizophilaet les espèces bactériennes testées. L’activité antimicrobienne du T6SS de S. rhizophila limite la transmission de Xcc8004 de la graine de radis à la plantule en conditions gnotobiotiques. Cette activité module également la dynamique d’assemblage des communautés bactériennes lors de la transition graine-plantule en sol non stérile. La composition du consortium microbien co-inoculé sur graine influence l’avantage compétitif conféré par le T6SS à S. rhizophila. La compétition d’interférence médiée par le T6SS intervient donc bien dans la dynamique d’assemblage du microbiote des plantes et l'inoculation de consortiums bactériens composés de bactéries porteuses de T6SS apparait comme une solution potentielle de réduction de la transmission des agents phytopathogènes aux plantules
Seeds represent the initial inoculum source for plant microbiota. During germination, the release of exudates near the seeds triggers intense microbial competitions, which play a pivotal role in the assembly of the plant microbiota. This thesis work aims to explore the role of interference competition mediated by the Type VI secretion system (T6SS). The T6SS of a strain of Stenotrophomonas rhizophila, a bacterium efficiently transmitted to seedlings, was used as a study model. This T6SS inhibits the growth of many bacterial species in vitro, including the phytopathogenic strain Xanthomonas campestris pv. campestris 8004 (Xcc8004). This inhibition of bacterial growth is correlated with the phylogenetic and metabolic proximity between S. rhizophila and the tested bacterial species. The antimicrobial activity of S. rhizophila T6SS limits the transmission of Xcc8004 from radish seed to seedling under gnotobiotic conditions. Its activity also influences the dynamics of bacterial community assembly during the seed-to-seedling transition in non sterile soil. The composition of the co-inoculated microbial consortium on the seed affects the competitive advantage conferred by the T6SS to S. rhizophila. Therefore, T6SS-mediated interference competition plays a significant role in the assembly dynamics of the plant microbiota, and the inoculation of bacterial consortia composed of T6SS-carrying bacteria appears as a potential solution for reducing the transmission of phytopathogenic agents to seedlings