Purification and characterization of thermostable α-amylase produced from Bacillus licheniformis So-B3 and its potential in hydrolyzing raw starch.

AIMS: This work was achieved to obtain the optimum culture conditions of the thermostable alpha-amylase produced by thermophilic Bacillus licheniformis SO-B3. Furthermore, the α-amylase was purified and then characterized, and also its kinetic parameters were determined. MATERIALS AND METHODS: A new thermotolerant bacteria called Bacillus licheniformis SO-B3 employed in this work was isolated from a sample of thermal spring mud in Sirnak (Meyremderesi). Several parameters such as the impact of temperature, time, and pH on enzyme production were examined. Thin-Layer Chromatography (TLC) was employed to analyze the end-products of soluble starch hydrolysis, and the utilization of purified α-amylase in the clarification of unripe apple juices was studied. KEY FINDINGS: The highest enzyme production conditions were determined as 35 °C, 36th hour, and pH 7.0. Thermostable α-amylase was purified by 70% ammonium sulfate precipitation, DEAE-cellulose ion-exchange chromatography, and dialysis, with a 51-purification fold and 30% yield recovery. The Km and Vmax values for this enzyme were 0.004 mM and 3.07 µmol min-1 at 70 °C, respectively. The α-amylase's molecular weight was found as 74 kDa. In addition, α-amylase showed a good degradation rate for raw starch. SIGNIFICANCE: It was hypothesized that Bacillus licheniformis SO-B3 could be used as an α-amylase source. These findings displayed that purified enzyme could be utilized in fruit juice industries for clarification of apple juice and raw starch hydrolyzing.

Ketone Body Signaling Mediates Intestinal Stem Cell Homeostasis and Adaptation to Diet.

Little is known about how metabolites couple tissue-specific stem cell function with physiology. Here we show that, in the mammalian small intestine, the expression of Hmgcs2 (3-hydroxy-3-methylglutaryl-CoA synthetase 2), the gene encoding the rate-limiting enzyme in the production of ketone bodies, including beta-hydroxybutyrate (ßOHB), distinguishes self-renewing Lgr5+ stem cells (ISCs) from differentiated cell types. Hmgcs2 loss depletes ßOHB levels in Lgr5+ ISCs and skews their differentiation toward secretory cell fates, which can be rescued by exogenous ßOHB and class I histone deacetylase (HDAC) inhibitor treatment. Mechanistically, ßOHB acts by inhibiting HDACs to reinforce Notch signaling, instructing ISC self-renewal and lineage decisions. Notably, although a high-fat ketogenic diet elevates ISC function and post-injury regeneration through ßOHB-mediated Notch signaling, a glucose-supplemented diet has the opposite effects. These findings reveal how control of ßOHB-activated signaling in ISCs by diet helps to fine-tune stem cell adaptation in homeostasis and injury.

Olive mill wastewater treatment in single-chamber air-cathode microbial fuel cells.

Olive mill wastewaters create significant environmental issues in olive-processing countries. One of the most hazardous groups of pollutants in these wastewaters is phenolic compounds. Here, olive mill wastewater was used as substrate and treated in single-chamber air-cathode microbial fuel cells. Olive mill wastewater yielded a maximum voltage of 381 mV on an external resistance of 1 kΩ. Notable decreases in the contents of 3,4-dihydroxybenzoic acid, tyrosol, gallic acid and p-coumaric acid were detected. Chemical oxygen demand removal rates were 65 % while removal of total phenolics by the process was lower (49 %). Microbial community analysis during the olive mill wastewater treating MFC has shown that both exoelectrogenic and phenol-degrading microorganisms have been enriched during the operation. Brevundimonas-, Sphingomonas- and Novosphingobium-related phylotypes were enriched on the anode biofilm, while Alphaproteobacteria and Bacteriodetes dominated the cathode biofilm. As one of the novel studies, it has been demonstrated that recalcitrant olive mill wastewaters could be treated and utilized for power generation in microbial fuel cells.