Search Results (6)

Bacillus subtilis (Bs) is a bacterium that benefits plants and is used in the production of bio-fungicides. The cultivation of Bs is a crucial step in bio-control preparation production, as it greatly impacts the quality and price of the final product. In a series of shake flask experiments, we investigated the economically feasible broth composition for spore production of Bacillus subtilis MSCL 897, a Latvian soil isolate. Our study investigated the impact of utilizing legume-based flours (such as broad bean, grey pea, and soybean) as the primary nitrogen source, along with sugar-beet molasses, sucrose, or glucose as the carbon source, and yeast extract, peptone, and corn-steep liquor as growth factor additives. Additionally, we examined the effect of using (NH₄)₂HPO₄ or urea as supplementary nitrogen sources, as well as previously established media formulations, on spore yield. Our results showed that a culture medium composed of broad bean flour (10 g/L) and molasses (10 g/L) led to spore productivity of 1.35 ± 0.47 × 10⁸ CFU/mL at 48 h. By enriching the culture medium base constituents with a minor (0.5–1.0 g/L) yeast extract or corn-steep liquor additive, a notable increase in spore productivity was observed, with values of 2.00 ± 0.28 × 10⁸ and 2.34 ± 0.18 × 10⁸ CFU/mL at 48 h, respectively, and sporulation efficiency > 80–90%. As a result, we achieved a high spore yield of the Bacillus subtilis MSCL 897 strain, demonstrating the competitiveness of our approach, which relied on a low-cost medium made mainly from locally available and renewable raw materials. Full article

Alliances of microbiota with plants are masked by the inability of in vitro cultivation of their bulk. Pure cultures piled in international centers originated from dissimilar environments/hosts. Reporting that plant root/leaf-based culture media support the organ-specific growth of microbiota, it was of interest to further investigate if a plant-based medium prepared from homologous (maize) supports specific/adapted microbiota compared to another prepared from heterologous plants (sunflower). The culture-independent community of maize phyllosphere was compared to communities cross-cultivated on plant broth-based media: CFU counts and taxa prevalence (PCR-DGGE; Illumina MiSeq amplicon sequencing). Similar to total maize phyllospheric microbiota, culture-dependent communities were overwhelmed by Proteobacteria (>94.3–98.3%); followed by Firmicutes (>1.3–3.7%), Bacteroidetes (>0.01–1.58%) and Actinobacteria (>0.06–0.34%). Differential in vitro growth on homologous versus heterologous plant-media enriched/restricted various taxa. In contrast, homologous cultivation over represented members of Proteobacteria (ca. > 98.0%), mainly Pseudomonadaceae and Moraxellaceae; heterologous cultivation and R2A enriched Firmicutes (ca. > 3.0%). The present strategy simulates/fingerprints the chemical composition of host plants to expand the culturomics of plant microbiota, advance real-time in vitro cultivation and lab-keeping of compatible plant microbiota, and identify preferential pairing of plant-microbe partners toward future synthetic community (SynComs) research and use in agriculture. Full article

Micronutrients, such as zinc (Zn), are essential for the growth and development of a wide range of crops. To overcome Zn deficiency in the soil, Zn-solubilizing bacteria (ZSB) have recently been employed. In the present study, samples from the rice fields in the state of Selangor, Malaysia, were collected to isolate, characterize, and identify the ZSB. A total of 88 strains were isolated, and only 9 strains were able to solubilize the insoluble Zn on zinc oxide (ZnO)-, zinc carbonate (ZnCO₃)-, and zinc phosphate (Zn₃(PO₄)₂)-amended Tris-minimal media agar and broth assays. The highest Zn solubilization (20.99%) was measured for the TM23 isolate when exposed to Zn₃(PO₄)₂-modified media culture, whereas ZnCO₃ showed the lowest (3.35%) Zn solubilization by ZSB. In addition, nine isolated ZSB also exhibited plant-growth-promoting (PGP) traits, including nitrogen fixation ability, siderophore production, indole acetic acid production (35.28–65.48 mL⁻¹), phosphate solubilization (27.69–77.38%), enzyme hydrolysis, and production of organic acids. Most of the isolated strains (88) were Gram-negative, except for TM54, which was Gram-positive. The four potential ZSB isolates based on 16RS rDNA sequence analysis were identified as Serratia sp. and Acinetobacter sp. Hence, this study’s findings suggest that these isolates could be prospective candidates to overcome Zn deficiencies and reduce the consumption of chemical fertilizers in agricultural areas. Full article

Plant microbiota support the diversity and productivity of plants. Thus, cultivation-dependent approaches are indispensable for in vitro manipulation of hub taxa. Despite recent advances in high-throughput methods, cultivability is lagging behind other environmental microbiomes, notably the human microbiome. As a plant-based culturing strategy, we developed culture media based on a broth of cooked aqueous mixtures of host plants. This improved the in vitro growth of representative isolates of plant microbiota and extended the in situ recovery of plant microbiota. With clover, 16S rRNA gene sequencing of representative isolates confirmed the predominance of Firmicutes, Alphaproteobacteria and Gammaproteobacteria, and less frequently Bacteroidetes and Actinobacteria. Whereas bovine-based culture media (modified R2A) confined the diversity to Firmicutes, the plant broth-based culture media revealed a wider scope of endophytes beyond rhizobia, i.e., multiple genera such as Chryseobacterium, Cronobacter, Kosakonia, Tsukamurella, and a potentially/presumptive novel species. Matrix-assisted laser desorption/ionization time-of-flight (MADI-TOF) analysis clustered isolates according to their plant niches, the endo-phyllosphere/endo-rhizosphere. We recommend the plant broth for simplicity, reproducibility and perdurable storage, supporting future culturomics applications, good laboratory practice (GLP) and good manufacturing practice (GMP). The strategy creates an “in-situ-similis” vegan nutritional matrix to analyze microbial diversity and reveal novel microbial resources pertinent to biotechnological and environmental applications. Full article

Phoxim, a type of organophosphorus pesticide (OP), is widely used in both agriculture and fisheries. The persistence of phoxim has caused serious environmental pollution problems. In this study, Bacillus amyloliquefaciens YP6 (YP6), which is capable of promoting plant growth and degrading broad-spectrum OPs, was used to study phoxim degradation. Different culture media were applied to evaluate the growth and phoxim degradation of YP6. YP6 can grow rapidly and degrade phoxim efficiently in Luria–Bertani broth (LB broth) medium. Furthermore, it can also utilize phoxim as the sole phosphorus source in a mineral salt medium. Response surface methodology was performed to optimize the degradation conditions of phoxim by YP6 in LB broth medium. The optimum biodegradation conditions were 40 °C, pH 7.20, and an inoculum size of 4.17% (v/v). The phoxim metabolites, O,O-diethylthiophosphoric ester, phoxom, and α-cyanobenzylideneaminooxy phosphonic acid, were confirmed by liquid chromatography–mass spectrometry. Meanwhile, transcriptome analysis and qRT-PCR were performed to give insight into the phoxim-stress response at the transcriptome level. The hydrolase-, oxidase-, and NADPH-cytochrome P450 reductase-encoding genes were significantly upregulated for phoxim hydrolysis, sulfoxidation, and o-dealkylation. Furthermore, the phoxim biodegradation pathways by YP6 were proposed, for the first time, based on transcriptomic data and product analysis. Full article

The aim of this work was to develop the composition of a medium for the cultivation of six microbial strains forming a deodorizing consortium: Pseudomonas fluorescens, Enterococcus faecium, Bacillus subtilis, Bacillus megaterium, Leuconostoc mesenteroides and Lactobacillus plantarum. The study focused on the optimization of a highly efficient culture medium composed of readily available components of plant origin to maximize microbial biomass yields, and to create a less expensive alternative to the commercial Tryptic Soy Broth medium (TSB). After preliminary efficiency screening of all tested media components, we selected four substrates for further optimization—soy protein concentrate (SPC), glucose or sucrose, and phosphate salts. The final concentrations of all components were fine-tuned using the Taguchi design for experiments according to an L₉ array. Taguchi optimization led to formulation of a culture medium, which was approximately 5 times cheaper than TSB (depending on the components used). Consequently, microbial biomass yields were improved by up to 15-fold (1564%), depending on the strain. The results obtained in the laboratory experiments were then confirmed in pilot- (42 L) and industrial- (300 L) scale fermentation. Our results show that this method of using a parallel culture microbioreactor with the Taguchi approach can be recommended for optimization of culture media based on substrates of plant origin. Full article