Impact of sterilization and chemical fertilizer on the microbiota of oil palm seedlings.

Soil nutrients and microbiota are known as essential components for healthy plant growth and crop productivity. However, limited studies have been conducted on the importance of soil microbiota in the early growth of oil palm seedlings (Elaeis guineensis Jacq.) under the influence of nitrogen, phosphorus and potassium (NPK) compound fertilizer (nitrogen, phosphorus, and potassium). In this study, we analyzed the root microbial community associated with seedlings grown under normal and sterilized soil conditions to ascertain the microbial strains potentially associated with soil, plant health and chemical fertilizer efficiency. Oil palm seedlings were grown under four treatments: (i) fertilized normal soil (+FN), (ii) unfertilized normal soil (-FN), (iii) fertilized sterilized soil (+FS) and (iv) unfertilized sterilized soil (-FS). Our findings revealed that chemical fertilizer promoted the growth of the copiotrophs Pseudomonadota and Bacteroidota in the control +FN, which are known to degrade complex polysaccharides. After autoclaving, the soil macronutrient content did not change, but soil sterilization reduced microbial diversity in the +FS and -FS treatments and altered the soil microbiota composition. Sterilized soil with a depleted microbial population adversely affected crop growth, which was exacerbated by fertilizer use. In the rhizosphere and rhizoplane compartments, a total of 412 and 868 amplicon sequence variances (ASVs) were found depleted in the +FS and -FS treatments, respectively. Several genera were identified in the ASVs with diminished abundance, including Humibacter, Microbacterium, Mycobacterium, 1921-2, HSB OF53-F07, Mucilaginibacter, Bacillus, Paenibacillus, and several unclassified genera, suggesting their possible roles in promoting the plant growth of oil palm seedlings. Soil sterilization might remove these beneficial microbes from the bulk soil pool, affecting the colonization ability in the rhizocompartments as well as their role in nutrient transformation. Therefore, this study provides useful insights concerning the benefits of a soil microbiome survey before making fertilizer recommendations.

Aspergillus fumigatus AR04 obeys Arrhenius' rule in cultivation temperature shifts from 30 to 40°C.

To set a benchmark in fungal growth rate, a differential analysis of prototrophic Aspergillus fumigatus AR04 with three ascomycetes applied in > 103 t year-1 scale was performed, i.e. Ashbya gosspyii (riboflavin), Aspergillus niger (citric acid) and Aspergillus oryzae (food-processing). While radial colony growth decreased 0.5-fold when A. gossypii was cultivated at 40°C instead of 28°C, A. fumigatus AR04 responded with 1.7-fold faster hyphal growth. A. niger and A. oryzae formed colonies at 40°C, but not at 43°C. Moreover, all A. fumigatus strains tested grew even at 49°C. In chemostat experiments, A. fumigatus AR04 reached steady state at a dilution rate of 0.7 h-1 at 40°C, 120% more than reported for A. gossypii at 28°C. To study mycelial growth rates under unlimited conditions, carbon dioxide increase rates were calculated from concentrations detected online in the exhaust of batch fermentations for 3 h only. All rates calculated suggest that A. fumigatus AR04 approximates Arrhenius' rule when comparing short cultivations at 30°C with those at 40°C. Linearization of the exponential phase and comparison of the slopes revealed an increase to 192% by the 10°C up-shift.

Comparative metabolomics of Phialemonium curvatum as an omnipotent fungus cultivated on crude palm oil versus glucose.

BACKGROUND: Sugars and triglycerides are common carbon sources for microorganisms. Nonetheless, a systematic comparative interpretation of metabolic changes upon vegetable oil or glucose as sole carbon source is still lacking. Selected fungi that can grow in acidic mineral salt media (MSM) with vegetable oil had been identified recently. Hence, this study aimed to investigate the overall metabolite changes of an omnipotent fungus and to reveal changes at central carbon metabolism corresponding to both carbon sources. RESULTS: Targeted and non-targeted metabolomics for both polar and semi-polar metabolites of Phialemonium curvatum AWO2 (DSM 23903) cultivated in MSM with palm oil (MSM-P) or glucose (MSM-G) as carbon sources were obtained. Targeted metabolomics on central carbon metabolism of tricarboxylic acid (TCA) cycle and glyoxylate cycle were analysed using LC-MS/MS-TripleQ and GC-MS, while untargeted metabolite profiling was performed using LC-MS/MS-QTOF followed by multivariate analysis. Targeted metabolomics analysis showed that glyoxylate pathway and TCA cycle were recruited at central carbon metabolism for triglyceride and glucose catabolism, respectively. Significant differences in organic acids concentration of about 4- to 8-fold were observed for citric acid, succinic acid, malic acid, and oxaloacetic acid. Correlation of organic acids concentration and key enzymes involved in the central carbon metabolism was further determined by enzymatic assays. On the other hand, the untargeted profiling revealed seven metabolites undergoing significant changes between MSM-P and MSM-G cultures. CONCLUSIONS: Overall, this study has provided insights on the understanding on the effect of triglycerides and sugar as carbon source in fungi global metabolic pathway, which might become important for future optimization of carbon flux engineering in fungi to improve organic acids production when vegetable oil is applied as the sole carbon source.

Practicing evidence-based psychiatry- 2. Interpreting integrative literature: Systematic reviews and meta-analyses.

The practice of evidence-based medicine (EBM) requires the ability to adequately appraise relevant clinical evidence with the intention of making an evidence-based treatment decision. Broadly, there are three available sources of information available to the practicing clinician: individual studies, reviews of the literature, and practice guidelines. In the first article in the series, we described the threats to validity (T2V) approach in evaluating evidence and specifically discussed the different threats to validity in applying the findings of a single study to an individual patient. In this article, we describe the five steps of a systematic review and evaluate threats to validity at each of these steps. We illustrate the method by evaluating a review relevant to the treatment question presented in a clinical vignette. We discuss results of the meta-analytic review about comparative antipsychotic effectiveness in patients with schizophrenia and consider application of its conclusions to the question of which antipsychotic to select for the particular patient with schizophrenia utilizing the T2V approach.