AiiM,a Novel Class of N-Acylhomoserine Lactonase from the Leaf-Associated Bacterium Microbacterium testaceum

N-Acylhomoserine lactones (AHLs) are used as quorum-sensing signal molecules by many Gram-negative bacteria. We have reported that Microbacterium testaceum StLB037, which was isolated from the leaf surface of potato, has AHL-degrading activity. In this study, we cloned the aiiM gene from the genomic library of StLB037, which has AHL-degrading activity and shows high homology with the α/β hydrolase fold family from Actinobacteria. Purified AiiM as a maltose binding fusion protein showed high degrading activity of AHLs with both short- and long-chain AHLs with or without substitution at carbon 3. High-performance liquid chromatography analysis revealed that AiiM works as an AHL lactonase that catalyzes AHL ring opening by hydrolyzing lactones. In addition, expression of AiiM in the plant pathogen Pectobacterium carotovorum subsp. carotovorum reduced pectinase activity markedly and attenuated soft rot symptoms on potato slices. In conclusion, this study indicated that AiiM might be effective in quenching quorum sensing of P. carotovorum subsp. carotovorum.Quorum sensing is a cell-cell communication mechanism that depends on cell population density in bacteria (3, 7). In many Gram-negative bacteria, several kinds of N-acyl-l-homoserine lactones (AHLs) have been identified as signal compounds involved in this mechanism, and these are termed autoinducers (3, 7). AHL-mediated quorum sensing regulates the expression of many genes, including those responsible for bioluminescence, the production of pigments and antibiotics, and other processes (7). Many Gram-negative plant pathogens produce AHLs and regulate their virulence by AHL-mediated quorum sensing (31). For instance, Pectobacterium carotovorum subsp. carotovorum (formerly Erwinia carotovora), which causes soft rot diseases in many plant species, induces the production of various exoenzymes and plant tissue maceration by AHLs (1). Pantoea stewartii and Pantoea ananatis produce AHLs and regulate exopolysaccharide biosynthesis and the infection of plants (15, 32). In general, AHL-negative mutants show defects in pathogenicity, so it is expected that disrupting or manipulating quorum-sensing signals could inhibit the expression of virulence and infection of host cells.Recently, many AHL-degrading genes have been cloned and characterized from various bacteria. Genes encoding AHL lactonase, which catalyzes AHL ring opening by hydrolyzing lactones, have been cloned from Bacillus sp., Arthrobacter sp., Agrobacterium tumefaciens, and Rhodococcus erythropolis (5, 23, 30, 34). Genes encoding AHL acylase, which hydrolyze the amide bond of AHL, have been cloned from Ralstonia sp., Anabaena sp., Streptomyces sp., Shewanella sp., and Pseudomonas aeruginosa (11, 12, 16, 22, 25). Human and murine paraoxonase degrades AHL by hydrolyzing its lactone ring (21). Novel AHL lactonase genes have been isolated from a metagenomic library which was constructed from environmental soil samples (24, 27). AHL-degrading genes have also been utilized in the biocontrol of plant diseases. Expression of aiiA in transformed P. carotovorum subsp. carotovorum significantly attenuates pathogenicity on some crops (5). Transgenic plants expressing AHL lactonase exhibited significantly enhanced resistance to the infection of P. carotovorum subsp. carotovorum (4).We have reported the isolation of AHL-degrading Microbacterium testaceum StLB037 from the leaf surface of potato (Solanum tuberosum) (17). In coinfections, we found that StLB037 interrupted quorum-sensing-dependent bacterial infection by the plant pathogen P. carotovorum subsp. carotovorum. In this study, we report the cloning and characterization of a novel AHL lactonase gene (aiiM) from the chromosome of StLB037. In addition, we evaluated the potential use of heterologous aiiM gene expression in quenching quorum sensing in the plant pathogen P. carotovorum subsp. carotovorum.     

Plasmid transformation and expression of the firefly luciferase in Microbacterium testaceum type and endophytic colonizing field strains

Microbacterium testaceum is a predominant endophytic bacterial species isolated from corn and sorghum in the midwestern United States. The development of genetic transfer systems for M. testaceum may enable its use for biocontrol and other applications. The type strain (IFO 12675) and field isolates (SE017, SE034, and CE648) were grown to mid-exponential phase, concentrated (1.0 x 1011 CFU x mL(-1)), electroporated (Escherichia coli-Clavibacter shuttle plasmid pDM302), and plated on TSA with 10 microg x mL(-1) chloramphenicol. Transformation efficiencies averaged 140 CFU x microg(-1) of DNA. Restriction endonuclease analysis showed that pDM302 was not altered after extraction from transformants and re-introduction into E. coli. Transformants with pDM302 were also subjected to nonselective growth conditions, with the frequency of loss after one passage being 84% for IFO 12675 and 88% for SE034. We inserted the green fluorescent protein and the firefly luciferase (FFlux) reporter genes into pDM302, confirming the expression of FFlux in IFO 12675 and SE034. The SE034 FFlux strain was recovered from inoculated corn in greenhouse studies and found to fluoresce by luminometry. These results in M. testaceum demonstrate for the first time its transformability, pDM302 replication, FFlux gene expression, and the recovery of the FFlux recombinant strain from inoculated corn.     

Description of a Novel Actinobacterium Microbacterium assamensis sp. nov., Isolated from Water Sample Collected from the River Brahmaputra, Assam, India

A Gram-positive, yellow pigmented actinobacterium, strain S2-48(T) was isolated from water sample collected from the river Brahmaputra, Assam, India and subjected to a polyphasic taxonomic study. Most of the physiological and biochemical properties, major fatty acids (C(15:0) Anteiso, iso C(16:0) and C(17:0) Anteiso), estimated DNA G+C content (70.2 mol%) and 16S rRNA gene sequence analysis showed that strain S2-48(T) belonged to the genus Microbacterium. Strain S2-48(T) exhibited highest 16S rRNA gene sequence similarity with Microbacterium testaceum (97.0%); however, the DNA-DNA relatedness value between strain S2-48(T) and M. testaceum was 9.1%. On the basis of differential phenotypic characteristics and genotypic distinctiveness, strain S2-48(T) should be classified within the genus Microbacterium as a novel species, for which the name Microbacterium assamensis is proposed. The type strain is S2-48(T) (=MTCC 10486(T) = DSM 23998(T)).     

An aberrant hemolysin of Vibrio cholerae non-O1.

An aberrant hemolysin produced by a Vibrio cholerae non-O1 strain N037 (N037-hly) was purified and characterized. N037-Hly was antigenically very similar to El Tor hemolysin but differed in molecular weight (48,000 vs. 60,000), interaction with glucose, and hemolytic activity. Of 100 V. cholerae non-O1 strains other than the N037 strain examined, none produced this aberrant hemolysin. The N-terminal amino acid sequence of N037-hly was highly homologous to that of El Tor hemolysin.     

Trichoderma harzianum SQR-T037 rapidly degrades allelochemicals in rhizospheres of continuously cropped cucumbers

To alleviate the stress of continuous cropping for cucumber continuous cropping (CCC) system, a beneficial fungus Trichoderma harzianum SQR-T037 (SQR-T037) was isolated and applied to soil to degrade allelochemicals exuded from cucumber plants in a Rhizobox experiment. The following phenolic acids (PAs), classified as allelochemicals, were isolated and identified from cucumber rhizospheres: 4-hydroxybenzoic acid, vanillic acid, ferulic acid, benzoic acid, 3-phenylpropionic acid, and cinnamic acid. Mixed PAs added in potato dextrose broth, each with 0.2 gram per liter, were completely degraded by SQR-T037 after 170 h of incubation. In Rhizobox experiments, inoculation of SQR-T037 in the CCC soil also degraded the PAs exuded from cucumber plant roots. This degradation was 88.8% for 4-hydroxybenzoic acid, 90% for vanillic acid, 95% for benzoic acid, and 100% for ferulic acid, 3-phenylpropionic acid, and cinnamic acid at 45 days after plantation. Simultaneously, a significant (p ≥ 0.05) decrease in the disease index of Fusarium wilt and an increase in dry weights of cucumber plants were obtained in pot experiments by application of SQR-T037. This was mostly attributed to degradation of PAs exuded from cucumber roots in CCC soil by SQR-T037 and alleviation of the allelopathic stress. Application of beneficial microorganisms, such as SQR-T037 that biodegrades allelochemicals, is a highly efficient way to resolve the problems associated with continuous cropping system.     

The lactic acid bacterium Pediococcus acidilactici suppresses autoimmune encephalomyelitis by inducing IL-10-producing regulatory T cells

Background

Certain intestinal microflora are thought to regulate the systemic immune response. Lactic acid bacteria are one of the most studied bacteria in terms of their beneficial effects on health and autoimmune diseases; one of which is Multiple sclerosis (MS) which affects the central nervous system. We investigated whether the lactic acid bacterium Pediococcus acidilactici, which comprises human commensal bacteria, has beneficial effects on experimental autoimmune encephalomyelitis (EAE), an animal model of MS.

Methodology/Principal Findings

P. acidilactici R037 was orally administered to EAE mice to investigate the effects of R037. R037 treatment suppressed clinical EAE severity as prophylaxis and therapy. The antigen-specific production of inflammatory cytokines was inhibited in R037-treated mice. A significant increase in the number of CD4⁺ Interleukin (IL)-10-producing cells was observed in the mesenteric lymph nodes (MLNs) and spleens isolated from R037-treated naive mice, while no increase was observed in the number of these cells in the lamina propria. Because only a slight increase in the CD4⁺Foxp3⁺ cells was observed in MLNs, R037 may primarily induce Foxp3⁻ IL10-producing T regulatory type 1 (Tr1) cells in MLNs, which contribute to the beneficial effect of R037 on EAE.

Conclusions/Significance

An orally administered single strain of P. acidilactici R037 ameliorates EAE by inducing IL10-producing Tr1 cells. Our findings indicate the therapeutic potential of the oral administration of R037 for treating multiple sclerosis.     

Phylogenetic analysis of the coryneform bacteria by 5S rRNA sequences.

Nucleotide sequences of 5S rRNAs from 11 coryneform bacteria were determined. These were the type strains of Corynebacterium glutamicum, Corynebacterium xerosis, Brevibacterium linens, Arthrobacter globiformis, Cellulomonas biazotea, Aureobacterium testaceum, Curtobacterium citreum, Pimelobacter simplex, and Caseobacter polymorphus and representative strains of "Corynebacterium aquaticum" and Corynebacterium xerosis. A phylogenetic tree constructed from the sequences of these bacteria and published sequences indicated that the coryneform bacteria consist of a distinct eubacterial branch together with Streptomyces and Micrococcus spp. These bacteria could be further divided into four subgroups.     

A novel diacylglycerol-lactone shows marked selectivity in vitro among C1 domains of protein kinase C (PKC) isoforms alpha and delta as well as selectivity for RasGRP compared with PKCalpha

Although multiple natural products are potent ligands for the diacylglycerol binding C1 domain of protein kinase C (PKC), RasGRP, and related targets, the high conservation of C1 domains has impeded the development of selective ligands. We characterized here a diacylglycerol-lactone, 130C037, emerging from a combinatorial chemical synthetic strategy, which showed substantial selectivity. 130C037 gave shallow binding curves for PKC isoforms alpha, beta, gamma, delta, and epsilon, with apparent Ki values ranging from 340 nm for PKCalpha to 29 nm for PKCepsilon. When binding to isolated C1 domains of PKCalpha and -delta, 130C037 showed good affinity (Ki= 1.78 nm) only for deltaC1b, whereas phorbol 12,13-dibutyrate showed affinities within 10-fold for all. In LNCaP cells, 130C037 likewise selectively induced membrane translocation of deltaC1b. 130C037 bound intact RasGRP1 and RasGRP3 with Ki values of 3.5 and 3.8 nm, respectively, reflecting 8- and 90-fold selectivity relative to PKCepsilon and PKCalpha. By Western blot of Chinese hamster ovary cells, 130C037 selectively induced loss from the cytosol of RasGRP3 (ED50 = 286 nm), partial reduction of PKCepsilon (ED50 > 10 microm), and no effect on PKCalpha. As determined by confocal microscopy in LNCaP cells, 130C037 caused rapid translocation of RasGRP3, limited slow translocation of PKCepsilon, and no translocation of PKCalpha. Finally, 130C037 induced Erk phosphorylation in HEK-293 cells ectopically expressing RasGRP3 but not in control cells, whereas phorbol ester induced phosphorylation in both. The properties of 130C037 provide strong proof of principle for the feasibility of developing ligands with selectivity among C1 domain-containing therapeutic targets.     

Aberrant gene for El Tor hemolysin from Vibrio cholerae non-01, N037

Abstract Vibrio cholerae non-O1 strain N037 produced a hemolysin (N037-Hly) which was antigenically similar to El Tor hemolysin (El Tor-Hly) but different in molecular size, hemolytic activity, and glucose binding capacity. In the gene encoding N037-Hly, a 4-bp insertion into the structural gene for El Tor-Hly ( hlyA ) was found. The insertion resulted in a shift of codon frames generating a new stop codon in the downstream region. N037-Hly was a truncated product of El Tor-Hly sharing 90% of the N terminal region. This suggested that the 10% C-terminal region of El Tor-Hly is needed for the maximal hemolytic activity and glucose binding capacity.     

Solid-state fermentation of agro-industrial wastes to produce bioorganic fertilizer for the biocontrol of Fusarium wilt of cucumber in continuously cropped soil

Agro-industrial wastes of cattle dung, vinegar-production residue and rice straw were solid-state fermented by inoculation with Trichoderma harzianum SQR-T037 (SQR-T037) for production of bioorganic fertilizers containing SQR-T037 and 6-pentyl-α-pyrone (6PAP) to control Fusarium wilt of cucumber in a continuously cropped soil. Fermentation days, temperature, inoculum and vinegar-production residue demonstrated significant effects on the SQR-T037 biomass and the yield of 6PAP, based on fractional factorial design. Three optimum conditions for producing the maximum SQR-T037 biomass and 6PAP yield were predicted by central composite design and validated. Bioorganic fertilizer containing 8.46 log₁₀ ITS copies g⁻¹ dry weight of SQR-T037 and 1291.73 mg kg⁻¹ dry weight of 6PAP, and having the highest (p < 0.05) biocontrol efficacy, was achieved at 36.7 fermentation days, 25.9 °C temperature, 7.6% inoculum content, 41.0% vinegar-production residue, 20.0% rice straw and 39.0% cattle dung. This is a way to offer a high value-added use for agro-industrial wastes.     

Combining ability of summer-squash lines with different degrees of parthenocarpy and PRSV-W resistance

The aim was to assess heterosis in a set of 16 summer-squash hybrids, and evaluate the combining capacity of the respective parental lines, which differed as to the degree of parthenocarpy and resistance to PRSV-W (Papaya Ringspot Virus-Watermelon strain). The hybrids were obtained using a partial diallel cross design (4 × 4). The lines of parental group I were 1 = ABX-037G-77-03-05-01-01-bulk, 2 = ABX-037G-77-03-05-03-10-bulk, 3 = ABX-037G-77-03-05-01-04-bulk and 4 = ABX-037G-77-03-05-05-01-bulk, and of group II, 1' = ABX-037G-77-03-05-04-08-bulk, 2' = ABX-037G-77-03-05-02-11-bulk, 3' = Clarice and 4' = Caserta. The 16 hybrids and eight parental lines were evaluated for PRSV-W resistance, parthenocarpic expression and yield in randomized complete-block designs, with three replications. Parthenocarpy and the resistance to PRSV-W were rated by means of a scale from 1 to 5, where 1 = non-parthenocarpic or high resistance to PRSV-W, and 5 = parthenocarpic or high susceptibility to PRSV-W. Both additive and non-additive gene effects were important in the expression of parthenocarpy and resistance to PRSV-W. Whereas estimates of heterosis in parthenocarpy usually tended towards a higher degree, resistance to PRSV-W was towards higher susceptibility. At least one F(1) hybrid was identified with a satisfactory degree of parthenocarpy, resistance to PRSV-W and high fruit-yield.     

禽病原性大肠杆菌iro和tsh基因缺失株的构建

通过SSH和SCOTS研究, 铁系统(Iro)和温度敏感性血凝素(Tsh)在禽病原性大肠杆菌(APEC)的感染中可能发挥重要作用。基因检测发现, 在243个禽源大肠杆菌分离株中, 有205株为iro+菌株, 其中高、中度和低致病株分别为89.8%(184/205)、8.8%(18/205)和1.5%(3/205); 有167株为tsh+菌株, 高、中度、低致病株分别为87.4%(146/167)、12.6%(21/167)和0%(0/167), 结果显示iro+或tsh+株大多数为高致病株。为了确定iro和tsh基因在APEC致病力中的作用, 以APEC E037株为基础, 通过自杀性载体分别构建了iro和tsh基因缺失突变株E037(Δiro)、E037(Δtsh)和E037(ΔiroΔtsh)。动物感染性试验表明, 突变株在鸡体内的繁殖能力和致病性均明显下降, 但两个基因的协同致病作用不显著。进一步证实Iro和Tsh为APEC重要的致病因子。     

Effect of two types of biosurfactants on phenanthrene availability to the bacterial bioreporter Burkholderia sartisoli strain RP037

Biosurfactants are tensio-active agents that have often been proposed as a means to enhance the aqueous solubility of hydrophobic organic contaminants, such as polycyclic aromatic hydrocarbons (PAHs). Biosurfactant-producing bacteria such as those belonging to the genus Pseudomonas might therefore enhance PAH availability to PAH-degrading bacteria. We tested the effects of two types of biosurfactants produced by Pseudomonas sp., cyclic lipopeptides and rhamnolipids, on phenanthrene bioavailability. Bioavailability was judged from growth rates on phenanthrene and from specific induction of a phenanthrene-responsive GFP-reporter in Burkholderia sartisoli strain RP037. Co-culturing of strain RP037 with the lipopeptide-producing bacterium Pseudomonas putida strain PCL1445 enhanced GFP expression compared to a single culture, but this effect was not significantly different when strain RP037 was co-cultivated with a non-lipopeptide-producing mutant of P. putida. The addition of partially purified supernatant extracts from the P. putida lipopeptide producer equally did not unequivocally enhance phenanthrene bioavailability to strain RP037 compared to controls. In contrast, a 0.1% rhamnolipid solution strongly augmented RP037 growth rates on phenanthrene and led to a significantly larger proportion of cells in culture with high GFP expression. Our data therefore suggest that biosurfactant effects may be strongly dependent on the strain and type of biosurfactant.     

The potato P locus codes for flavonoid 3′,5′-hydroxylase

The potato P locus is required for the production of blue/purple anthocyanin pigments in any tissue of the potato plant such as tubers, flowers, or stems. We have previously reported, based on RFLP mapping in tomato, that the gene coding for the anthocyanin biosynthetic enzyme flavonoid 3,5-hydroxylase (f35h) maps to the same region of the tomato genome as P maps in potato. To further evaluate this association a Petunia f35h gene was used to screen a potato cDNA library prepared from purple-colored flowers and stems. Six positively hybridizing cDNA clones were sequenced and all appeared to be derived from a single gene that shares 85% sequence identity at the amino acid level with Petunia f35h. The potato gene cosegregated with purple tuber color in a diploid F₁ sub-population of 37 purple and 25 red individuals and was found to be expressed in tuber skin only in the presence of the anthocyanin regulatory locus I. A potato f35h cDNA clone was placed under the control of a doubled CaMV 35S promoter and introduced into the red-skinned cultivar Désirée. Tuber and stem tissues that are colored red in Désirée were purple in nine of 17 independently transformed lines.An erratum to this article can be found at     

<Emphasis Type="Italic">Acinetobacter kyonggiensis</Emphasis> sp. nov., a <Emphasis Type="Italic">β</Emphasis>-glucosidase-producing bacterium,isolated from sewage treatment plant

A Gram-negative, non-motile bacterium, designated KSL5401-037^T, was isolated from a sewage treatment plant in Gwangju in the Republic of Korea and was characterized using a polyphasic taxonomic approach. Comparative 16S rRNA gene sequence analysis showed that strain KSL5401-037^T belonged to the genus Acinetobacter in the family Moraxellaceae of the Gammaproteobacteria (Brisou and Prevot, 1954). According to a 16S rRNA gene sequence analysis, it was closely related to Acinetobacter johnsonii ATCC 17909^T (97.3%), A. bouvetii 4B02^T (97.2%), and A. beijerinckii 58a^T (96.8%). Chemotaxonomic data revealed that strain KSL5401-037^T possesses an ubiquinone system with Q-8 as the predominant compound and C_16:0 (19.2%), C_18:1 ω9c (19.5%), and summed feature 3 (C_16:1 ω6c / C_16:1 ω7c, 34.1%) as the predominant cellular fatty acids. The major polar lipids detected in strain KSL5401-037^T were diphosphatidylglycerol (DPG) and, phosphatidylethanolamine (PE), followed by phosphatidylglycerol (PG) and moderate amounts of phosphatidylcholine and phosphatidylserine. The G+C content of the genomic DNA was 41.2–42.1 mol%. Strain KSL5401-037^T exhibited relatively low levels of DNA-DNA relatedness with respect to A. johnsonii DSM 6963^T (17.7%) and A. bouvetii 4B02^T (9.3%). The DNA-DNA relatedness values, biochemical, and physiological characteristics of strain KSL5401-037^T strongly support its genotypic and phenotypic differentiation from other recognized type strains of the genus Acinetobacter. Based on these data, strain KSL5401-037^T (JCM 17071^T =KEMC 5401-037^T) should be classified in the genus Acinetobacter as a type strain of novel species, for which the name Acinetobacter kyonggiensis sp. nov. is proposed.     

乳酸菌抑制葡聚糖硫酸钠诱导的结肠黏膜氧化应激损伤的研究

目的研究乳酸菌抗氧化活性与缓解葡聚糖硫酸钠(DSS)诱导结肠炎的关系。方法评价5株乳酸菌体外抑制大鼠肝细胞脂质过氧化活性,用DSS诱导小鼠结肠炎模型研究抗氧化性不同的菌株体内抗氧化活性;小鼠分成7组,分别是Control组、DSS组、L.plantarum Fn008+DSS组、L.casei Fn012+DSS组、L.acidophilus Fn022+DSS组、L.sakei Fn034+DSS组和L.acidophilus Fn037+DSS组。结果体外实验表明,Fn022和Fn034的丙二醛(MDA)抑制率高于LGG,但差异无统计学意义,Fn008和Fn037的MDA抑制率显著低于LGG,Fn012的MDA抑制率最低。体内实验表明,DSS可导致小鼠氧化应激,升高结肠内容物的自由基水平,降低结肠抗氧化能力;Fn008和Fn037预处理能显著降低DSS诱导结肠内容物的自由基水平,Fn008能显著降低结肠组织的髓过氧化物酶(MPO)水平,提高结肠抗氧化能力,Fn022和Fn034的干预能力居中,Fn012的干预能力最弱。相关性分析表明乳酸菌体外MDA清除率与体内MPO有负相关趋势(r=-0.862,P=0.06)。结论乳酸菌抗氧化活性与其在肠道抑制炎性细胞激活的作用有关,本实验中Fn008和Fn037具有显著的体内抗氧化作用。     

Solubilisation of Phosphate and Micronutrients by Trichoderma harzianum and Its Relationship with the Promotion of Tomato Plant Growth

Trichoderma harzianum strain SQR-T037 is a biocontrol agent that has been shown to enhance the uptake of nutrients (macro- and microelements) by plants in fields. The objective of this study was to investigate the contribution of SQR-T037 to P and microelement (Fe, Mn, Cu and Zn) nutrition in tomato plants grown in soil and in hydroponic conditions. Inoculation with SQR-T037 significantly improved the biomass and nutrient uptake of tomato seedlings grown in a nutrient-limiting soil. So we investigated the capability of SQR-T037 to solubilise sparingly soluble minerals in vitro via four known mechanisms: acidification by organic acids, chelation by siderophores, redox by ferric reductase and hydrolysis by phytase. SQR-T037 was able to solubilise phytate, Fe₂O₃, CuO, and metallic Zn but not Ca₃(PO₄)₂ or MnO₂. Organic acids, including lactic acid, citric acid, tartaric acid and succinic acid, were detected by HPLC and LC/MS in two Trichoderma cultures. Additionally, we inoculated tomato seedlings with SQR-T037 using a hydroponic system with specific nutrient deficiencies (i.e., nutrient solutions deficient in P, Fe, Cu or Zn and supplemented with their corresponding solid minerals) to better study the effects of Trichoderma inoculation on plant growth and nutrition. Inoculated seedlings grown in Cu-deficient hydroponic conditions exhibited increases in dry plant biomass (92%) and Cu uptake (42%) relative to control plants. However, we did not observe a significant effect on seedling biomass in plants grown in the Fe- and Zn-deficient hydroponic conditions; by contrast, the biomass decreased by 82% in the P-deficient hydroponic condition. Thus, we demonstrated that Trichoderma SQR-T037 competed for P (phytate) and Zn with tomato seedlings by suppressing root development, releasing phytase and/or chelating minerals. The results of this study suggest that the induction of increased or suppressed plant growth occurs through the direct effect of T. harzianum on root development, in combination with indirect mechanisms, such as mineral solubilisation (including solubilisation via acidification, redox, chelation and hydrolysis).