scholarly journals Sequential Production of ᴅ-xylonate and Ethanol from Non-Detoxified Corncob at Low-pH by Pichia kudriavzevii via a Two-Stage Fermentation Strategy

2021 ◽  
Vol 7 (12) ◽  
pp. 1038
Author(s):  
Hao Ji ◽  
Ke Xu ◽  
Xiameng Dong ◽  
Da Sun ◽  
Libo Jin
Keyword(s):  
Ph Control ◽  
Low Ph ◽  
Economic Viability ◽  
Excellent Performance ◽  
Two Stage ◽  
Pichia Kudriavzevii ◽  
Comprehensive Utilization ◽  
Ph Conditions ◽  
Fermentation Strategy ◽  
Simultaneous Saccharification

Improving the comprehensive utilization of sugars in lignocellulosic biomass is a major challenge for enhancing the economic viability of lignocellulose biorefinement. A robust yeast Pichia kudriavzevii N-X showed excellent performance in ethanol production under high temperature and low pH conditions and was engineered for ᴅ-xylonate production without xylitol generation. The recombinant strain P. kudriavzevii N-X/S1 was employed for sequential production of ᴅ-xylonate and ethanol from ᴅ-xylose, feeding on ᴅ-glucose without pH control in a two-stage strategy of aerobic and shifting micro-aerobic fermentation. Acid-pretreated corncob without detoxification and filtration was used for ᴅ-xylonate production, then simultaneous saccharification and ethanol fermentation was performed with cellulase added at pH 4.0 and at 40 °C. By this strategy, 33.5 g/L ᴅ-xylonate and 20.8 g/L ethanol were produced at yields of 1.10 g/g ᴅ-xylose and 84.3% of theoretical value, respectively. We propose a promising approach for the sequential production of ᴅ-xylonate and ethanol from non-detoxified corncob using a single microorganism.

Transcriptional profiling reveals molecular basis and the role of arginine in response to low-pH stress in Pichia kudriavzevii

2019 ◽  
Author(s):  
Hao Ji ◽  
Xiameng Dong ◽  
Kailun Zhang ◽  
Libo Jin ◽  
Renyi Peng ◽  
...  
Keyword(s):  
Organic Acids ◽  
Molecular Basis ◽  
Transcriptional Profiling ◽  
Cell Aggregation ◽  
Membrane Lipid ◽  
Low Ph ◽  
Pichia Kudriavzevii ◽  
Ph Stress ◽  
Ph Conditions

Abstract BackgroundThe non-conventional yeast Pichia kudriavzevii possesses a unique ability to tolerate various environmental stresses particularly low-pH stress. Thus, it is considered to be a promising biotechnological host for the production of various organic acids under low-pH conditions. However, little is known about the low-pH stress response in P. kudriavzevii, which significantly restricts its future development. ResultsIn this study, P. kudriavzevii JLY1107 showed great tolerance to low-pH stress, but its cell aggregation upon acidic conditions is unfavorable for the development of low-pH fermentation. To explore the molecular basis, we conducted RNA-Seq to compare global gene expression in response to low-pH. Among the 429 differentially expressed genes, the genes associated with regulation of membrane lipid composition, filamentous growth and arginine metabolism were selected for in-depth discussions. The up-regulation of genes associated with arginine uptake and degradation suggests a potential role of arginine in response to low-pH strsss. We therefore present data supporting the hypothesis that P. kudriavzevii maintains intracellular homeostasis by using the ammonia produced by arginine catabolism. Furthermore, external addition of arginine significantly enhances growth and reduces cell aggregation of P. kudriavzevii under low-pH conditions.ConclusionsArginine was demonstrated to be a promising molecule for improving cell growth and preventing cell aggregation under extremely low-pH conditions. Our study is a step towards developing the non-conventional yeast P. kudriavzevii as a platform host for the production of organic acids under low-pH conditions.

The anaerobic treatment of a ligno-cellulosic substrate offering little natural pH buffering capacity

1998 ◽  
Vol 38 (4-5) ◽  
pp. 29-35 ◽  
Author(s):  
C. J. Banks ◽  
P. N. Humphreys
Keyword(s):  
Ph Control ◽  
Anaerobic Treatment ◽  
Buffering Capacity ◽  
Single Stage ◽  
Stable Operation ◽  
Reactor Performance ◽  
Two Stage ◽  
Ph Buffering ◽  
Stage System ◽  
The Stability

The stability and operational performance of single stage digestion with and without liquor recycle and two stage digestion were assessed using a mixture of paper and wood as the digestion substrate. Attempts to maintain stable digestion in both single stage reactors were unsuccessful due to the inherently low natural buffering capacity exhibited; this resulted in a rapid souring of the reactor due to unbuffered volatile fatty acid (VFA) accumulation. The use of lime to control pH was unsatisfactory due to interference with the carbonate/bicarbonate equilibrium resulting in wide oscillations in the control parameter. The two stage system overcame the pH stability problems allowing stable operation for a period of 200 days without any requirement for pH control; this was attributed to the rapid flushing of VFA from the first stage reactor into the second stage, where efficient conversion to methane was established. Reactor performance was judged to be satisfactory with the breakdown of 53% of influent volatile solids. It was concluded that the reactor configuration of the two stage system offers the potential for the treatment of cellulosic wastes with a sub-optimal carbon to nitrogen ratio for conventional digestion.

Expression patterns of two carbonic anhydrase genes, Na+/K+-ATPase and V-type H+-ATPase, in the freshwater crayfish, Cherax quadricarinatus, exposed to low pH and high pH

2017 ◽  
Vol 65 (1) ◽  
pp. 50 ◽  
Author(s):  
Muhammad Yousuf Ali ◽  
Ana Pavasovic ◽  
Peter B. Mather ◽  
Peter J. Prentis
Keyword(s):  
Carbonic Anhydrase ◽  
Expression Patterns ◽  
Maximum Level ◽  
Low Ph ◽  
Freshwater Crayfish ◽  
Α Subunit ◽  
Cherax Quadricarinatus ◽  
High Ph ◽  
Internal Ph ◽  
Ph Conditions

Carbonic anhydrase (CA), Na+/K+-ATPase (NKA) and Vacuolar-type H+-ATPase (HAT) play vital roles in osmoregulation and pH balance in decapod crustaceans. As variable pH levels have a significant impact on the physiology of crustaceans, it is crucial to understand the mechanisms by which an animal maintains its internal pH. We examined expression patterns of cytoplasmic (CAc) and membrane-associated form (CAg) of CA, NKA α subunit and HAT subunit a in gills of freshwater crayfish, Cherax quadricarinatus, at three pH levels – 6.2, 7.2 (control) and 8.2 – over 24 h. Expression levels of CAc were significantly increased at low pH and decreased at high pH conditions 24 h after transfer. Expression increased at low pH after 12 h, and reached its maximum level by 24 h. CAg showed a significant increase in expression at 6 h after transfer at low pH. Expression of NKA significantly increased at 6 h after transfer to pH 6.2 and remained elevated for up to 24 h. Expression for HAT and NKA showed similar patterns, where expression significantly increased 6 h after transfer to low pH and remained significantly elevated throughout the experiment. Overall, CAc, CAg, NKA and HAT gene expression is induced at low pH conditions in freshwater crayfish.

scholarly journals Dynamic response in the larval geoduck clam proteome to elevated pCO2

2019 ◽  
Author(s):  
Emma Timmins-Schiffman ◽  
José M. Guzmán ◽  
Rhonda Elliott ◽  
Brent Vadopalas ◽  
Steven B. Roberts
Keyword(s):  
Ocean Acidification ◽  
Pacific Coast ◽  
Low Ph ◽  
Molecular Physiology ◽  
Proteomics Analysis ◽  
Bivalve Larvae ◽  
Energetic Stress ◽  
The Pacific ◽  
Aquaculture Industry ◽  
Ph Conditions

AbstractPacific geoduck clams (Panopea generosa) are found along the Northeast Pacific coast where they are significant components of coastal and estuarine ecosystems and the basis of a growing and highly profitable aquaculture industry. The Pacific coastline, however, is also the sight of rapidly changing ocean habitat, including significant reductions in pH. The impacts of ocean acidification on invertebrate bivalve larvae have been widely documented and it is well established that many species experience growth and developmental deficiencies when exposed to low pH. As a native of environments that have historically lower pH than the open ocean, it is possible that geoduck larvae are less impacted by these effects than other species. Over two weeks in larval development (days 6-19 post-fertilization) geoduck larvae were reared at pH 7.5 or 7.1 in a commercial shellfish hatchery. Larvae were sampled at six time points throughout the period for a in-depth proteomics analysis of developmental molecular physiology. Larvae reared at low pH were smaller than those reared at ambient pH, especially in the prodissoconch II phase of development. Competency for settlement was also delayed in larvae from the low pH conditions. A comparison of proteomic profiles over the course of development reveal that these differing phenotypic outcomes are likely due to environmental disruptions to the timing of molecular physiological events as suites of proteins showed differing profiles of abundance between the two pH environments. Ocean acidification likely caused an energetic stress on the larvae at pH 7.1, causing a shift in physiological prioritization with resulting loss of fitness.

scholarly journals Variation in brachiopod microstructure and isotope geochemistry under low pH–ocean acidification–conditions

2018 ◽  
Author(s):  
Facheng Ye ◽  
Hana Jurikova ◽  
Lucia Angiolini ◽  
Uwe Brand ◽  
Gaia Crippa ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Ocean Acidification ◽  
Isotope Geochemistry ◽  
Shell Growth ◽  
Low Ph ◽  
Secondary Layer ◽  
Ph Conditions ◽  
One Year ◽  
The Impact ◽  
Δ13c And Δ18o

Abstract. Throughout the last few decades and in the near future CO2–induced ocean acidification is potentially a big threat to marine calcite-shelled animals (e.g., brachiopods, bivalves, corals and gastropods). Despite the great number of studies focusing on the effects of acidification on shell growth, metabolism, shell dissolution and shell repair, the consequences on biomineral formation remain poorly understood, and only few studies addressed contemporarily the impact of acidification on shell microstructure and geochemistry. In this study, a detailed microstructure and stable isotope geochemistry investigation was performed on nine adult brachiopod specimens of Magellania venosa (Dixon, 1789), grown in the natural environment as well as in controlled culturing experiments at different pH conditions (ranging 7.35 to 8.15 ± 0.05) over different time intervals (214 to 335 days). Details of shell microstructural features, such as thickness of the primary layer, density and size of endopunctae and morphology of the basic structural unit of the secondary layer were analysed using scanning electron microscopy (SEM). Stable isotope compositions (δ13C and δ18O) were tested from the secondary shell layer along shell ontogenetic increments in both dorsal and ventral valves. Based on our comprehensive dataset, we observed that, under low pH conditions, M. venosa produced a more organic-rich shell with higher density of and larger endopunctae, and smaller secondary layer fibres, when subjected to about one year of culturing. Also, increasingly negative δ13C and δ18O values are recorded by the shell produced during culturing and are related to the CO2–source in the culture setup. Both the microstructural changes and the stable isotope results are similar to observations on brachiopods from the fossil record and strongly support the value of brachiopods as robust archives of proxies for studying ocean acidification events in the geologic past.

scholarly journals ISOLATION, SCREENING, AND CHARACTERIZATION OF PROBIOTICS (LACTIC ACID BACTERIA) ANTAGONISTIC AGAINST Candida albicans

2017 ◽  
Vol 4 (2) ◽  
pp. 263
Author(s):  
Ida Ayu Ketut Ariningsih ◽  
Yan Ramona ◽  
Nyoman Semadi Antara
Keyword(s):  
Candida Albicans ◽  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Reproductive Tract ◽  
Antagonistic Activity ◽  
Low Ph ◽  
Production Test ◽  
Ph Conditions ◽  
High Level

Candidacies in female reproductive tract are mainly caused by Candida albicans. This infection often causes serious problems, particularly on their reproductive tract (genital part). Until recently, control of this infection has relied on the use of antibiotics. However due to numerous bad side effects of antibiotics, lactic acid bacteria have been proposed as an alternative method to control the growth of Candida albicans. Therefore, this research was aimed to isolate, screen, and characterize lactic acid bacterial isolates (LAB) antagonistic against Candida albicans (the causative agent of candidacies infection in reproductive tract of human). LABs were isolated from various fermented foods, such as tape ketan and kimchi. Isolation of LABs was conducted by applying dilution and spread plate method on MRS agar medium supplemented with BCP indicator to distinguish LABs from non acid-producing bacteria. Colonies with indication to produce acid were screened for antagonistic activity against C. albicans on MRS agar and followed by characterization of those isolates (Gram stain, catalase production test, oxydase production, gas production test, resistance test to low pH conditions and to high level of NaDC (sodium deoxicolic), and test for ability to convert colic acid (CA) into deoxicolic acid (DCA)). The results showed that 46 LAB isolates were successfully isolated from samples of tape ketan and kimchi. Among those, 7 isolates showed antagonistic activity against C. albicans in in vitro tests. All these 7 candidates were also found to be resistance to low pH conditions (up to pH 2) and to high level of NaDC (up to 0.6 mM). Four most potential isolates were further testes for ability to convert colic acid into deoxycolic acid and none showed positive result, indicating that they all showed initial potential and safe for future human probiotic development (especially to be used to treat patients infected by C. albicans).

Production of bioethanol and xylitol from non-detoxified corn cob via a two-stage fermentation strategy

2020 ◽  
Vol 310 ◽  
pp. 123427 ◽  
Author(s):  
Cong Du ◽  
Yimin Li ◽  
Han Zong ◽  
Tangguo Yuan ◽  
Wenjie Yuan ◽  
...  
Keyword(s):  
Corn Cob ◽  
Two Stage ◽  
Fermentation Strategy

Two-stage biofiltration of sulfides and VOCs from wastewater treatment plants

2000 ◽  
Vol 42 (5-6) ◽  
pp. 411-418 ◽  
Author(s):  
J.S. Devinny ◽  
D.E. Chitwood
Keyword(s):  
Organic Compounds ◽  
Wastewater Treatment Plants ◽  
Pilot Scale ◽  
Low Ph ◽  
Single Stage ◽  
Two Stage ◽  
Neutral Ph ◽  
Support Medium ◽  
Waste Air ◽  
Air Streams

Hydrogen sulfide and volatile organic compounds are often found together in waste air streams. This combination is difficult to treat by biofiltration because oxidation of the sulfide produces acid, reducing the pH in the biofilter. Rapid declines in pH can inhibit treatment of organic compounds. A two-stage biofilter, with the first stage operated at low pH and an inorganic support medium, and the second operated at neutral pH with an organic support can eliminate the problem. A pilot-scale facility was operated on this principle. Comparisons were made among two-stage treatment, single-stage low pH treatment, and single-stage uncontrolled treatment to determine which of the strategies was most effective. In two-stage treatment the first stage did provide protection for the second, allowing it to operate at neutral pH. Single-stage low pH treatment was effective at removing sulfide and many organic compounds, and may be sufficient for many applications.

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