Insights into Xylan Degradation and Haloalkaline Adaptation through Whole-Genome Analysis of Alkalitalea saponilacus, an Anaerobic Haloalkaliphilic Bacterium Capable of Secreting Novel Halostable Xylanase

Abstract

The obligately anaerobic haloalkaliphilic bacterium Alkalitalea saponilacus can use xylan as the sole carbon source and produce propionate as the main fermentation product. Using mixed carbon sources of 0.4% (w/v) sucrose and 0.1% (w/v) birch xylan, xylanase production from A. saponilacus was 3.2-fold greater than that of individual carbon sources of 0.5% (w/v) sucrose or 0.5% (w/v) birch xylan. The xylanse is halostable and exhibits optimal activity over a broad salt concentration (2–6% NaCl). Its activity increased approximately 1.16-fold by adding 0.2% (v/v) Tween 20. To understand the potential genetic mechanisms of xylan degradation and molecular adaptation to saline-alkali extremes, the complete genome sequence of A. saponilacus was performed with the pacBio single-molecule real-time (SMRT) and Illumina Misseq platforms. The genome contained one chromosome with a total size of 4,775,573 bps, and a G+C genomic content of 39.27%. Ten genes relating to the pathway for complete xylan degradation were systematically identified. Furthermore, various genes were predicted to be involved in isosmotic cytoplasm via the “compatible-solutes strategy” and cytoplasmic pH homeostasis though the “influx of hydrogen ions”. The halostable xylanase from A. saponilacus and its genomic sequence information provide some insight for potential applications in industry under double extreme conditions.

The Effects of Consuming White Button Mushroom Agaricus bisporus on the Brain and Liver Metabolome Using a Targeted Metabolomic Analysis

“…Here, we present additional evidence that feeding WBM-supplemented diets to pigs for six weeks can also affect the brain and liver metabolome associated with changes in the intestinal microbiome. An increased correlation between acyl-alkyl-phosphatidylcholine in the hippocampus and cortex and bacteria within the Cryomorphaceae (Fluviicola), Flammeovirgaceae (Limibacter) [26] and within Marinilabilaceae (Alkalitalea), an anaerobic haloalkaliphilic bacterium responsible for xylan degradation in wheat-straw based compost used for Agaricus bisporus growth [63,64], suggested that this lipid species was significantly increased in the brain by feeding WBM. Interaction network analysis indicated a positive correlation between phosphatidylcholine (PC) in the hippocampus and cortex and bacteria within the Lactobacilaceae, Cryomorphaceae, Ruminococcaceae, Lachnospiraceae, Flammeovirgaceae families induced by feeding six servings of WBM diet.…”

Safety Evaluation and Whole Genome Sequencing of Aspergillus japonicas PJ01 Reveal Its Potential to Degrade Citrus Segments in Juice Processing

“…Endo-1,4-beta-xylanase is the main degradation enzyme of xylanase [36]. The whole genome sequencing showed that A. japonicas PJ01 has four genes related to endo-1,4-beta-xylanase, and its activity is stronger than that of A. saponilacus, which has one gene related to endo-1,4-beta-xylanase [37]. CAZy annotation showed that there are more genes in A. japonicas PJ01 related to carbohydrate activity than Dickeya sp.…”

Insights through Genetics of Halophilic Microorganisms and Their Viruses

“…Halophilic microorganisms are considered a resource for industrial catalysts that function in organic solvent, high salt or other extreme conditions that most organisms cannot tolerate. Liao et al [9] provide insight into an anaerobic haloalkaliphilic bacterium, Alkalitalea saponilacus, that uses xylan as a sole carbon and energy source and produces propionic acid as a major product. Microbes and the enzymes that hydrolze xylan (xylanases) are useful in the biobleaching of wood pulp as well as in the depolymerization of lignocellulosic biomass to generate renewable fuels and chemicals.…”

“…Microbes and the enzymes that hydrolze xylan (xylanases) are useful in the biobleaching of wood pulp as well as in the depolymerization of lignocellulosic biomass to generate renewable fuels and chemicals. In this special issue, the authors [9] find A. saponilacus secretes an extracellular fraction that hydrolyzes xylan in high salt and, through genomic sequencing, identify gene homologs relating to the pathway for complete xylan degradation. One future aim of this work is to develop a method to recover the xylanase for use in biobleaching wood pulp.…”