Stenotrophomonas Rhizophila Research Articles

Inhibition effect of non-contact biocontrol bacteria and plant essential oil mixture on the generation of N-nitrosamines in deli meat during storage

To reduce the risk of N-nitrosamines in deli meat products, this study formulated a novel non-contact N-nitrosamines inhibiting preservative IV (NIP-IV) consisting of biocontrol bacteria and plant essential oils (EOs) (Stenotrophomonas rhizophila SR-1 + Paenibacillus provencensis PP-2 + Bacillus subtilis CF-3+ cinnamon EO + grapefruit EO). Luncheon pork, spiced beef, and red sausage were taken as representatives of typical deli meat products and used to validate the effectiveness of NIP-IV in inhibiting N-nitroso dimethylamine (NDMA) production. The results showed that NIP-IV restrain protein degradation and lipid oxidation in deli meat products and effectively control microbial activity. Biogenic amines, such as phenethylamine, spermidine, cadaverine, and tyramine, were reduced. The conversion of nitrite to NDMA in deli meats was effectively inhibited by NIP-IV. Volatile organic compounds were the key to excellent NIP-IV non-contact preservation. Butyric acid, 3-methylbutanoic acid, benzaldehyde, d-limonene, and (E)-cinnamaldehyde were significantly negatively correlated with NDMA in deli meat products.

Biofilms from the Kapova Cave Walls as a Source of Hydrolase Producers

The studies of bacterial communities from extreme econiches are presently aimed mainly at analyzing the biodiversity of microorganisms using molecular biology methods. Cultivated bacteria from karst caves represent a unique group of microorganisms, the biochemical potential of which has been poorly studied. In the present work, bacteria from biofilms on the walls of the Kapova Cave (Shulgan-Tash Nature Reserve, Bashkortostan) were isolated and characterized in order to assess the ability of identified isolates to produce extracellular hydrolytic enzymes. Most of the isolates (89%) were members of the phylum Proteobacteria, with the remaining ones belonging to the phyla Actinobacteria, Firmicutes, and Bacteroidetes, which accounted for 5, 4, and 2% of the isolates, respectively. Strains with high levels of secreted protease, RNase, and amylase activity were identified as Stenotrophomonas rhizophila, Lysinibacillus fusiformis, and Pseudomonas stutzeri, respectively.

Ecofriendly biosynthesis of copper nanoparticles from novel marine S. rhizophila species for enhanced antibiofilm, antimicrobial and antioxidant potential

Marine microorganisms offer a promising avenue for the eco-friendly synthesis of nanoparticles due to their unique biochemical capabilities and adaptability to various environments. This study focuses on exploring the potential of a marine bacterial species, Stenotrophomonas rhizophila BGNAK1, for the synthesis of biocompatible copper nanoparticles and their application for hindering biofilms formed by monomicrobial species. The study begins with the isolation of the novel marine S. rhizophila species from marine soil samples collected from the West coast region of Kerala, India. The isolated strain is identified through 16S rRNA gene sequencing and confirmed to be S. rhizophila species. Biosynthesis of copper nanoparticles using S. rhizophila results in the formation of nanoparticles with size of range 10–50 nm. The nanoparticles exhibit a face-centered cubic crystal structure of copper, as confirmed by X-Ray Diffraction analysis. Furthermore, the synthesized nanoparticles display significant antimicrobial activity against various pathogenic bacteria and yeast. The highest inhibitory activity was against Staphylococcus aureus with a zone of 27 ± 1.00 mm and the least activity was against Pseudomonas aeruginosa with a zone of 22 ± 0.50 mm. The zone of inhibition against Candida albicans was 16 ± 0.60 mm. The antibiofilm activity against biofilm-forming clinical pathogens was evidenced by the antibiofilm assay and SEM images. Additionally, the copper nanoparticles exhibit antioxidant activity, as evidenced by their scavenging ability against DPPH, hydroxyl, nitric oxide, and superoxide radicals, as well as their reducing power in the FRAP assay. The study highlights the potential of the marine bacterium S. rhizophila BGNAK1 for the eco-friendly biosynthesis of copper nanoparticles with diverse applications. Synthesized nanoparticles exhibit promising antibiofilm, antimicrobial, and antioxidant properties, suggesting their potential utility in various fields such as medicine, wastewater treatment, and environmental remediation.

Interspecies interactions in dairy biofilms drive community structure and response against cleaning and disinfection

Interspecies interactions within a biofilm community influence population dynamics and community structure, which in turn may affect the bacterial stress response to antimicrobials. This study was conducted to assess the impact of interactions between Kocuria salsicia and a three-species biofilm community (comprising Stenotrophomonas rhizophila, Bacillus licheniformis, and Microbacterium lacticum) on biofilm mass, the abundance of individual species, and their survival under a laboratory-scale cleaning and disinfection (C&D) regime. The presence of K. salsicia enhanced the cell numbers of all three species in pairwise interactions. The outcomes derived from summing up pairwise interactions did not accurately predict the bacterial population dynamics within communities of more than two species. In four-species biofilms, we observed the dominance of S. rhizophila and B. licheniformis, alongside a concurrent reduction in the cell counts of K. salsicia and M. lacticum. This pattern suggests that the underlying interactions are not purely non-transitive; instead, a more complex interplay results in the dominance of specific species. We observed that bacterial spatial organization and matrix production in different mixed-species combinations affected survival in response to C&D. Confocal microscopy analysis of spatial organization showed that S. rhizophila localized on the biofilm formed by B. licheniformis and M. lacticum, and S. rhizophila was more susceptible to C&D. Matrix production in B. licheniformis, evidenced by alterations in biofilm mass and by scanning electron microscopy, demonstrated its protective role against C&D, not only for this species itself, but also for neighbouring species. Our findings emphasise that various social interactions within a biofilm community not only affect bacterial population dynamics but also influence the biofilm community's response to C&D stress.

Ef fect of a Marine Bacterium and Vermicompost on Antioxidant Properties and Fruit Quality of Solanum lycopersicum L.

The present study aimed to evaluate caporal hybrid tomatoes’ antioxidant capacity and fruit quality under greenhouse conditions when applying a combination of a marine bacteria (Stenotrophomonas rhizophila) and dif ferent doses of vermicompost. A random block design was used, with 12 treatments: Inorganic fertilized (IF, control treatment), S. rhizophila (Sr), 60, 150, and 300 g of vermicompost (V), and the combination of Sr+V (Sr+V60, Sr+V150, and Sr+V300), with 20 repetitions each. Plant height, stem diameter, number of flowers, number of fruits, colony-forming units (CFU), polar and equatorial diameter of the fruit, fruit firmness, titratable acidity, total soluble solids (TSS), lycopene, vitamin C, fruit weight and yield per plant were evaluated. These were analysed with the Statistical Package and the Tukey mean test with a significance level of 0.05%. The analysis showed significant dif ferences for all the variables evaluated with Sr+V300 as the best treatment. It is concluded that the use of bacterium isolated from marine environments in combination with vermicompost favors the antioxidant contents and fruit yield being an alternative use in this vegetable.

Analysis of diversity and function of epiphytic bacterial communities associated with macrophytes using a metagenomic approach

Epiphytic bacteria constitute a vital component of aquatic ecosystems, pivotal in regulating elemental cycling. Despite their significance, the diversity and functions of epiphytic bacterial communities adhering to various submerged macrophytes remain largely unexplored. In this study, we employed a metagenomic approach to investigate the diversity and function of epiphytic bacterial communities associated with six submerged macrophytes: Ceratophyllum demersum, Hydrilla verticillata, Myriophyllum verticillatum, Potamogeton lucens, Stuckenia pectinata, and Najas marina. The results revealed that the predominant epiphytic bacterial species for each plant type included Pseudomonas spp., Microbacterium spp., and Stenotrophomonas rhizophila. Multiple comparisons and linear discriminant analysis effect size indicated a significant divergence in the community composition of epiphytic bacteria among the six submerged macrophytes, with 0.3–1% of species uniquely identified. Epiphytic bacterial richness associated with S. pectinata significantly differed from that of both C. demersum and H. verticillata, although no significant differences were observed in diversity and evenness. Functionally, notable variations were observed in the relative abundances of genes associated with carbon, nitrogen, and phosphorus cycling within epiphytic bacterial communities on the submerged macrophyte hosts. Among these communities, H. verticillata exhibited enrichment in genes related to the 3-hydroxypropionate bicycle and nitrogen assimilation, translocation, and denitrification. Conversely, M. verticillatum showcased enrichment in genes linked to the reductive citric acid cycle (Arnon-Buchanan cycle), reductive pentose phosphate cycle (Calvin cycle), polyphosphate degradation, and organic nitrogen metabolism. In summary, our findings offer valuable insights into the diversity and function of epiphytic bacteria on submerged macrophyte leaves, shedding light on their roles in lake ecosystems.

Interspecific interactions facilitate keystone species in a multispecies biofilm that promotes plant growth.

Microorganisms colonizing plant roots co-exist in complex, spatially structured multispecies biofilm communities. However, little is known about microbial interactions and the underlying spatial organization within biofilm communities established on plant roots. Here, a well-established four-species biofilm model (Stenotrophomonas rhizophila, Paenibacillus amylolyticus, Microbacterium oxydans, and Xanthomonas retroflexus, termed as SPMX) was applied to Arabidopsis roots to study the impact of multispecies biofilm on plant growth and the community spatial dynamics on the roots. SPMX co-culture notably promoted root development and plant biomass. Co-cultured SPMX increased root colonization and formed multispecies biofilms, structurally different from those formed by monocultures. By combining 16S rRNA gene amplicon sequencing and fluorescence in situ hybridization with confocal laser scanning microscopy, we found that the composition and spatial organization of the four-species biofilm significantly changed over time. Monoculture P. amylolyticus colonized plant roots poorly, but its population and root colonization were highly enhanced when residing in the four-species biofilm. Exclusion of P. amylolyticus from the community reduced overall biofilm production and root colonization of the three species, resulting in the loss of the plant growth-promoting effects. Combined with spatial analysis, this led to identification of P. amylolyticus as a keystone species. Our findings highlight that weak root colonizers may benefit from mutualistic interactions in complex communities and hereby become important keystone species impacting community spatial organization and function. This work expands the knowledge on spatial organization uncovering interspecific interactions in multispecies biofilm communities on plant roots, beneficial for harnessing microbial mutualism promoting plant growth.

Characteristics of Stenotrophomonas rhizophila Lipopolysaccharide, a Representative of Antarctica

Characteristics of Stenotrophomonas rhizophila Lipopolysaccharide, a Representative of Antarctica

A Novel Podophage StenR_269 Suggests a New Family in the Class Caudoviricetes.

Stenotrophomonas rhizophila was first discovered in soil; it is associated with the rhizosphere and capable of both protecting roots and stimulating plant growth. Therefore, it has a great potential to be used in biocontrol. The study of S. rhizophila phages is important for a further evaluation of their effect on the fitness and properties of host bacteria. A novel phage StenR_269 and its bacterial host S. rhizophila were isolated from a soil sample in the remediation area of a coal mine. Electron microscopy revealed a large capsid (~Ø80 nm) connected with a short tail, which corresponds to the podovirus morphotype. The length of the genomic sequence of the StenR_269 was 66,322 bp and it contained 103 putative genes; 40 of them encoded proteins with predicted functions, 3 corresponded to tRNAs, and the remaining 60 were identified as hypothetical ones. Comparative analysis indicated that the StenR_269 phage had a similar genome organization to that of the unclassified Xanthomonas phage DES1, despite their low protein similarity. In addition, the signature proteins of StenR_269 and DES1 had low similarity and these proteins clustered far from the corresponding proteins of classified phages. Thus, the StenR_269 genome is orphan and the analyzed data suggest a new family in the class Caudoviricetes.

Evaluation of microbial biocontrol agents for Ganoderma boninense management in oil palm nurseries

Importance of the workMicroorganisms play a pivotal role in the growth and development of plants, making their interaction a promising avenue for managing plant diseases, including those affecting oil palm cultivation. ObjectivesIn this study, endophytic microbes such as actinomycetes, bacteria, and fungi were isolated from healthy oil palm tissue in susceptible areas to serve as stock isolates. These isolates underwent in vitro evaluation to determine their efficacy in controlling Ganoderma boninense and to identify bioactive metabolites. Additionally, in planta tests were conducted using bioformulations. Materials & MethodsA dual culture assay was utilized to assess the inhibitory effects of three different stock isolates on G. boninense. To detect bioactive metabolites responsible for the inhibition, particularly phenazine and syringic acid, a series of procedures involving fermentation, extraction, and LC-MS analysis were employed. Furthermore, the efficacy of bioformulations employing various carriers and consisting of either microbial consortia was meticulously evaluated in a nursery setting. The main focus of this evaluation was to determine their capacity to effectively curb disease onset and maintain the vegetative growth of oil palm during the progression of G. boninense. ResultsSeveral strains of indigenous bacteria (Pseudomonas aeruginosa strain JQ-41, Serratia marcescens strain S16, Stenotrophomonas rhizophila strain CASMBAUDAL2), an actinobacterium (Streptomyces sp.), and a fungus (Trichoderma sp.) exhibited significant growth inhibition against G. boninense. Based on the results obtained from the LC-MS analysis of the ethyl acetate extract, it was revealed that the extract contains 2 compounds known as antifungal agents, namely phenazine and syringic acid. The most effective approach to mitigate infection involved the preventive application of bioformulations containing mixed bacterial isolates or microbial consortia. After 12 months of observation, these bioformulations demonstrated efficacy comparable to that of Marfu-P, a commercially available biofungicide for oil palm seedlings. Main findingThe study establishes the effectiveness of endophytic bioformulations as a viable strategy to manage the onset of G. boninense disease, highlighting the potential of microorganisms as an alternative solution for controlling basal stem rot in the nursery.

Biological control of tomato early blight in Pakistan using local rhizobacteria.

The biocontrol potential of soil microbes can reduce the extensive use of hazardous synthetic fungicides. This study was designed to find a strain of rhizobacteria indigenous to Pakistan with potential biocontrol against early blight of tomato caused by Alternaria solani and to characterize its biocontrol mechanisms. Among 88 strains tested for antagonism against A. solani on agar media, S27, Dt10 and 423, identified by 16S rRNA sequencing as strains of Bacillus amyloliquefaciens, B. cereus and Stenotrophomonas rhizophila, respectively, were the most inhibitory. When applied to detached tomato leaflets in Petri dish assays, the strains reduced lesion development by over 30% compared to the control. In greenhouse pot trials, the bacterial strains reduced early blight severity by over 50%. In three field trials, all three strains applied to tomato foliage slowed early blight disease progress and reduced disease severity, with B. amyloliquefaciens S27 reducing the area under the disease progress curve by up to 70%. All three strains showed protease, catalase and oxidase activities in vitro, but none produced β-1,3-glucanase and only B. cereus Dt10 showed slight chitinase activity. In a greenhouse experiment in which the bacteria were applied to tomato foliage prior to pathogen inoculation, bacteria-treated leaves had higher β-1,3-glucanase and chitinase levels than leaves inoculated only with the pathogen, indicating priming induction of response. Three rhizobacteria strains have the potential to control early blight of tomato under Pakistan's growing conditions, with B. amyloliquefaciens S27 being the most promising candidate for commercial development. Antagonism and induction of the priming response may be mechanisms of biocontrol by the bacterial strains. © 2023 Society of Chemical Industry.

Dynamic social interactions and keystone species shape the diversity and stability of mixed-species biofilms – an example from dairy isolates

Identifying interspecies interactions in mixed-species biofilms is a key challenge in microbial ecology and is of paramount importance given that interactions govern community functionality and stability. We previously reported a bacterial four-species biofilm model comprising Stenotrophomonas rhizophila, Bacillus licheniformis, Microbacterium lacticum, and Calidifontibacter indicus that were isolated from the surface of a dairy pasteuriser after cleaning and disinfection. These bacteria produced 3.13-fold more biofilm mass compared to the sum of biofilm masses in monoculture. The present study confirms that the observed community synergy results from dynamic social interactions, encompassing commensalism, exploitation, and amensalism. M. lacticum appears to be the keystone species as it increased the growth of all other species that led to the synergy in biofilm mass. Interactions among the other three species (in the absence of M. lacticum) also contributed towards the synergy in biofilm mass. Biofilm inducing effects of bacterial cell-free-supernatants were observed for some combinations, revealing the nature of the observed synergy, and addition of additional species to dual-species combinations confirmed the presence of higher-order interactions within the biofilm community. Our findings provide understanding of bacterial interactions in biofilms which can be used as an interaction–mediated approach for cultivating, engineering, and designing synthetic bacterial communities.

Evaluation of phenotypical and genotypical methods for the identification and typing of Stenotrophomonas maltophilia isolated from a pharmaceutical facility.

Evaluate methods for identification and typing of Stenotrophomonas maltophilia isolated from a pharmaceutical facility. From 270 S. maltophilia strains identified by VITEK®2, 40 were selected and submitted to MALDI TOF-MS, 16S and 23S rRNA gene analysis, ERIC-PCR, and antimicrobial susceptibility profile. 16S rRNA sequencing was able to identify 39 (97.5%) strains as Stenotrophomonas spp. and one (2.5%) as Luteimonas huabeiensis. MALDI TOF-MS identified 37 (92.5%) strains as S. maltophilia, and three (7.5%) were not identified. PCR targeting 23S rRNA yielded a positive result for 39 (97.5%) strains. However, after sequencing, two strains were identified as Stenotrophomonas rhizophila, showing false-positive results. The confirmed S. maltophilia strains (n=37) showed 35 distinct ERIC-PCR profiles and exhibited sensitivity to minocycline and levofloxacin, and six (16.3%) showed intermediate resistance to sulfamethoxazole-trimethoprim. MALDI-TOF MS was a satisfactory methodology for the identification of S. maltophilia, but expansion of the database is necessary for the identification of other species. 16S rDNA sequencing showed low resolution for Stenotrophomonas species differentiation. PCR targeting 23S rRNA could not differentiate S. maltophilia from S. rhizophila. ERIC-PCR was shown to be a useful tool for the microbial source tracking of S. maltophilia.

Stenotrophomonas rhizophila Ep2.2 inhibits growth of Botrytis cinerea through the emission of volatile organic compounds, restricts leaf infection and primes defense genes.

The bacterium Stenotrophomonas rhizophila is known to be beneficial for plants and has been frequently isolated from the rhizosphere of crops. In the present work, we isolated from the phyllosphere of an ornamental plant an epiphytic strain of S. rhizophila that we named Ep2.2 and investigated its possible application in crop protection. Compared to S. maltophilia LMG 958, a well-known plant beneficial species which behaves as opportunistic human pathogen, S. rhizophila Ep2.2 showed distinctive features, such as different motility, a generally reduced capacity to use carbon sources, a greater sensitivity to fusidic acid and potassium tellurite, and the inability to grow at the human body temperature. S. rhizophila Ep2.2 was able to inhibit in vitro growth of the plant pathogenic fungi Alternaria alternata and Botrytis cinerea through the emission of volatile compounds. Simultaneous PTR-MS and GC-MS analyses revealed the emission, by S. rhizophila Ep2.2, of volatile organic compounds (VOCs) with well-documented antifungal activity, such as furans, sulphur-containing compounds and terpenes. When sprayed on tomato leaves and plants, S. rhizophila Ep2.2 was able to restrict B. cinerea infection and to prime the expression of Pti5, GluA and PR1 plant defense genes.

Evaluation of Rhizobium along with Multifunctional Rhizobacteria for Improving the Growth and Yield of Black Gram [Vigna mungo (L.) Hepper

Background: Indigenous rhizobial populations may be unable to achieve successful symbiosis in the field due to rare population and unfavourable soil environment. Introduced plant growth promoting rhizobacteria (PGPR) are frequently linked to faster growth, development, and yield of plant with synergetic effect on indigenous Rhizobium bacteria. Furthermore, co-inoculating legumes with both Rhizobium and PGPR is proven more effective for improving nodulation as well as growth and development of legumes. Methods: The experiment was conducted at research farm of TCA, Dholi Muzaffarpur a campus of Dr. Rajendra Prasad Central Agriculture University, Pusa, Bihar during kharif season of 2021 to investigate the “Evaluation of Rhizobium along with multifunctional Rhizobacteria for improving the growth and yield of black gram [Vigna mungo (L.) Hepper]”. There were eight number of treatments and replicated thrice in a randomized block design. The treatment comprised as T1- control, T2- Rhizobium (Bradyrhizobium spp.), T3- Rhizobium + PUK-171 (Stenotrophomonas rhizophila), T4- Rhizobium + NE 10 (Bacillus cereus), T5-Rhizobium + Pseudomonas spp., T6-Rhizobium + LMSR 45 (Pantoea agglomerans), T7-Rhizobium + Methylobacterium, T8-N as per RDF. Result: The result revealed that co-inoculation of Rhizobium + PUK-171 (Stenotrophomonas rhizophila) significantly increase the plant height, number of leaves plant-1, number of branches plant‑1, plant dry weight, crop growth rate, and in nodule studies number of nodules plant-1, dry weight of nodules recoded significantly higher result as compare to T1, T2, and T8 and found at par with rest of treatment. In yield attributing character number of pods plant-1 recorded significantly higher result in co-inoculation of Rhizobium + PUK-171 (Stenotrophomonas rhizophila) and rest of character did not produce significant effect, in case of seed yield similar trends was followed, while in case of stover yield co-inoculation of Rhizobium along with Rhizobium + NE 10 (Bacillus cereus) recorded significantly higher result as compare to T1 and T8 and at par with rest of treatments. Harvest index did not produce significant effect.

Bacteria Stenotrophomonas are Promising Agents for the Treatment of Fat-containing Sewage

The results of monitoring the biological properties of indigenous bacterial strains isolated from soils, which for a long time were in contact with highly concentrated wastewater from the slaughterhouse of meat processing units, were presented. The resulting strains are able to grow on slaughterhouse wastewater in the presence of animal fats as a carbon source in concentration exceeding the maximum acceptable level for wastewater intended for biological treatment with activated sludge, it demonstrated combined high growth rates and resistance to chlorides. The stimulating effect of wastewater treated by combined indigenous bacterial strains on the germination of barley and corn seeds was confirmed. These strains were identified as Stenotrophomonas rhizophila.

Quorum sensing improves the plant growth-promoting ability of Stenotrophomonas rhizophila under saline-alkaline stress by enhancing its environmental adaptability.

Quorum sensing (QS) system has an essential function in plant growth-promoting rhizobacteria (PGPR) response to environmental stress and PGPR induction of plant tolerance to saline-alkaline stress. Nevertheless, there is a lack of understanding about how QS influences the growth-promoting effects of PGPR on plants. Stenotrophomonas rhizophila DSM14405T is a PGPR with a QS system, which can secrete diffusible signal factor (DSF), one of the QS signal molecules. In this study, we used the S. rhizophila wild type (WT) and an incompetent DSF production rpfF-knockout mutant strain to explore whether DSF-QS could affect the growth-promoting ability of PGPR in Brassica napus L. By measuring the seed germination rate, plant fresh weight, biomass, the total antioxidant capacity (T-AOC) level, and the content of chlorophyll in leaves, we found that DSF was unable to enhance the growth-promoting capacity of ΔrpfF and did not directly assist the plants in tolerating saline-alkaline stress. However, DSF aided S. rhizophila ΔrpfF in resisting stress during its effective period, and QS represents a continuous and precise regulatory mechanism. Altogether, our results show that DSF is helpful to improve the environmental adaptability and survival rate of S. rhizophila, thus indirectly improving the germination rate of seeds and helping plants grow under saline-alkaline stress. In this study, the mechanism of QS enhancing the environmental adaptability of PGPR was studied, which provided a theoretical basis for improving the application of PGPR to help plants better cope with saline-alkaline stress.

Promoting Strawberry (Fragaria × ananassa) Stress Resistance, Growth, and Yield Using Native Bacterial Biostimulants

Strawberry production is challenged by several abiotic and biotic stresses, such as drought, soil salinity, and the angular leaf spot (ALS) disease caused by Xanthomonas fragariae. In recent decades, the development of commercial products containing combinations of different Plant-Growth-Promoting (PGP) microorganisms has been one of the main focuses of agricultural research. However, their results are often erratic depending on crop species, environmental conditions, and competition among the different strains or indigenous plant microbiota. The use of beneficial microorganisms selected from the crop-specific microbiota may help overcome this limitation, promoting their utilization for sustainable agriculture. The culturable bacteriota of strawberry plants was screened to identify PGP activities in vitro. Bacterial isolates were tested in vivo on strawberry plants in both optimal and stress (X. fragariae infection or salinity) conditions, allowing the selection of strains of Pseudomonas fluorescens, Stenotrophomonas rhizophila, and Agrobacterium rubi whose application showed a significant increase in plant growth and fruit production (up to seven-fold), even under stress conditions, and the ability to control ALS by over 50%. Potential synergistic effects among PGP isolates were tested by coordinated inoculation. However, plant growth and fruit quality were not promoted, except for fruit weight and size, by coordinate inoculation in comparison to m23 and m27 single-strain treatment.

Characterization of the endophytic bacterial community of Bituminaria bituminosa plant grown in vitro and its interaction with the plant extract.

Bituminaria bituminosa is a medicinal plant recognized for its phytochemicals, such as furanocoumarins, pterocarpans, and flavonoids. Since the secondary metabolism is influenced by the plant-endophyte interactions, the endophytic bacterial community of B. bituminosa was explored and the possible interactions with the plant were described. Different bacterial strains were isolated from different organs of in vitro plants as shoots, roots, and seeds. The bacterial strains were identified and phenotypically characterized for different traits; strains were also exposed to different concentrations of B. bituminosa plant extract showing different susceptibility, probably determined by different secondary metabolites produced by the plant in the different organs (i.e. aerial parts and roots). Bacterial strains showed different phenotypic characteristics; the 6 detected haplotypes were dominated by a single species related to Stenotrophomonas rhizophila. Endophytes isolated from the aerial parts produced a higher indole-3-acetic acid (IAA) amount than those of the roots, while all strains were unable to produce biosurfactants and antagonistic activity toward the other strains. The research opens new perspectives for future analysis addressed to test the susceptibility of the endophytic bacterial community of B. bituminosa toward the pure compounds extracted from the plants, and to investigate the role of these compounds on the distribution of endophytes within the different plant tissues.

POME Processing with Bioremediation Using Indigenous Bacteria (Bacillus toyonensis and Stenotrophomonas rhizophila), Electrocoagulation, and Bioremediation assisted with Electrocoagulation Methods

Palm oil mill effluent (POME) is wastewater containing dissolved materials with concentrations above the threshold. Generally, POME processing in Indonesia uses an open pond system. It is less efficient because it requires large areas and causing greenhouse gas effects. This research aims to improve the POME processing, three methods were studied; bioremediation using enrich indigent lypholitics bacteria (Bacillus toyonensis and Stenotrophomonas rhizophila.), electrocoagulation system, and combination of those methods. The parameters were measured were oil and fat contents, COD, pH, TSS, TDS, Fe and Cu metals. In the electrocoagulation method, the electrodes were used iron electrodes with a variation of electrical voltage 1.5, 3, 4.5 and 6 V. The bioremediation using indigent bacteria results in the removal of oil and fat -74.62%, COD -52.44%, TSS -43.11% and pH 6.38 at the incubation time for 6 days, TDS 21.42%, Fe -5.3% and Cu -64.70%. The electrocoagulation methods results oil and fat removal were -93.27%, COD was -85.71%, TDS -39%, TSS -84%, Cu -46%, Fe +92.35%, and pH 11.39 at a voltage of 6 V for 6 h. The combination of the two methods can reduce oil and fat levels by -87.39%, COD -56.70%, TDS -0.42%, TSS +15.88%, Cu -23.33%, Fe +93.74% and pH 8.82. The three methods were studied can improve the POME processing significantly.