Microbial Fermentation of Organic Wastes for Production of Biofuels and Biochemicals

A special issue of Fermentation (ISSN 2311-5637). This special issue belongs to the section "Industrial Fermentation".

Deadline for manuscript submissions: closed (30 September 2022) | Viewed by 14871

Special Issue Editor

Department of Resources and Environment, School of Agriculture and Biology, Shanghai Jiao Tong University (SJTU), 800 Dongchuan Road, Minhang District, Shanghai 200240, China
Interests: biomass energy engineering; waste-to-resource technologies; environmental microbial technologies
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The management of organic wastes is currently a critical challenge globally. Of specific interest is food waste, agricultural waste, horticultural waste, animal manure, waste-activated sludge, wastewater, algal residues, and other industrial organic residues. Meanwhile, abundant renewable energy and resources remain unharnessed in such organic wastes. Therefore, to overcome the challenge, a large number of studies on microbial fermentation technologies have been conducted to convert varous organic wastes to biofuels  and biochemicals. For instance, anaerobic digestion of organic wastes can be performed for production of methane-rich biogas. Acidogenic fermentation of organic wastes can be conducted for production of carboxilic acids. Fermentation of oleaginous yeast can be carried out for production of microbial lipids. Additionally, biohydrogen can be obtained through dark fermentation of organic wastes, and polypeptide can be produced from fermentation of certain pure strains. These studies and related field-scale tests have contributed a lot to improving the sustainability of a circular economy.

To further enhance the process efficiency, studies on some enhancing strategies such as feedstock pretreatment, microbial bio-augmentation, and supplementation of additives in fermentaion bioreactors have been conducted with promising findings, but the efficiency requires further confirmation in larger-scale fermentation systems. To make the fermentation systems more practical, lifecycle assessment and cost–benefit analysis have been done to analyze the economic feasibility. The post-treatment of the fermentation liquid also requires more investigation to find the appropriate approaches that can reduce its environmental impacts and treatment cost.

In the global context of circular economy, this Special Issue aims to encourage and advance the research of microbial fermentation technologies for conversion of various organic wastes into biofules and biochemicals.

Dr. Le Zhang
Guest Editor

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Keywords

  • fermentation
  • organic wastes
  • biochemicals
  • biofuels
  • bioenergy
  • biogas
  • biohydrogen
  • anaerobic digestion
  • acidogenic fermentation
  • dark fermentation

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Published Papers (6 papers)

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Research

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16 pages, 2877 KiB  
Article
Lychee-Derived, Thermotolerant Yeasts for Second-Generation Bioethanol Production
by Phu Van Nguyen, Khanh Hoang Viet Nguyen, Ngoc Linh Nguyen, Xuan Tuy Thi Ho, Phuc Hung Truong and Kim Cuc Thi Nguyen
Fermentation 2022, 8(10), 515; https://0-doi-org.brum.beds.ac.uk/10.3390/fermentation8100515 - 05 Oct 2022
Cited by 8 | Viewed by 2059
Abstract
Thermotolerant yeasts are widely considered to be alternative strains to traditional yeasts for bioethanol production at high temperatures. In this study, thirty-two yeasts isolated from lychees were screened for thermotolerance, and seven selected isolates were identified as Candida tropicalis (isolates H8, H19, [...] Read more.
Thermotolerant yeasts are widely considered to be alternative strains to traditional yeasts for bioethanol production at high temperatures. In this study, thirty-two yeasts isolated from lychees were screened for thermotolerance, and seven selected isolates were identified as Candida tropicalis (isolates H8, H19, and H23), Meyerozyma guilliermondii (isolates H1 and H12) and Saccharomyces cerevisiae (isolates H10 and H18). They tolerated up to 45 °C, 12% (v/v) ethanol concentration, 10 g/L acetic acid, and 5 g/L furfural, respectively, and produced 47.96 to 70.18 g/L of ethanol from 160 g/L glucose at 40 °C during 48 h of fermentation. Among the evaluated yeasts, M. guilliermondii H1 showed great potential for second-generation bioethanol fermentation with its ability to ferment xylose and arabinose. Under the optimal conditions resulting from a Plackett Burman design and a Box Behnken design, the highest ethanol concentration of 11.12 g/L was produced from 40 g/L substrate-based sugarcane bagasse hydrolysate (non-detoxified hydrolysate) at 40 °C by M. guilliermondii H1. These findings suggested that the newly isolated thermotolerant yeast M. guilliermondii H1 is a good candidate for ethanol production from agricultural wastes. Full article
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14 pages, 312 KiB  
Article
Effects of Sour Yogurt as an Alternative Additive in Second Crop Corn Silage
by Sibel Soycan Önenç, Kadir Erten and Önder Canbolat
Fermentation 2022, 8(10), 494; https://0-doi-org.brum.beds.ac.uk/10.3390/fermentation8100494 - 28 Sep 2022
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Abstract
In this study, we evaluated the influence of sour yogurt as a natural microbial inoculant in second-crop corn silages. For this purpose, two trials with different dilution rates were conducted. In Trial I, the groups 10 g sour yogurt + 5 g distilled [...] Read more.
In this study, we evaluated the influence of sour yogurt as a natural microbial inoculant in second-crop corn silages. For this purpose, two trials with different dilution rates were conducted. In Trial I, the groups 10 g sour yogurt + 5 g distilled water (SY10-2), 20 g sour yogurt + 10 g distilled water (SY20-2), 30 g sour yogurt + 15 g distilled water (SY30-2), 40 g sour yogurt + 20 g distilled water (SY40-2), 50 g sour yogurt + 25 g distilled water (SY50-2) and no additives were added to the control (CON) group. The groups in Trial II, 10 g sour yogurt + 10 g distilled water (SY10-1), 20 g sour yogurt + 20 g distilled water (SY20-1), 30 g sour yogurt + 30 g distilled water (SY30-1), 40 g sour yogurt + 40 g distilled water (SY40-1), 50 g sour yogurt + 50 g distilled water (SY50-1) and 10 g of distilled water were added to the control (WCON) group. For the silages opened on the 90th day of ensiling, the highest lactic acid content was determined in the SY20-2 and SY20-1 groups (p < 0.05). The lowest amount of ammonia nitrogen was in the SY30-2 group (p < 0.05). In the aerobic period, the SY10-2 and SY20-2 groups remained more stable than the others. As a result, the SY20-2, SY30-2, SY20-1, and SY30-1 groups improved the fermentation quality of corn silages, but the effect on aerobic stability was not significant and was similarly found with the homofermentative bacterial inoculants. Full article
20 pages, 4296 KiB  
Article
Bioconversion of Glycerol into Lactic Acid by a New Bacterial Strain from the Brazilian Cerrado Soil
by Raissa G. M. R. Barroso, Jamille R. C. Lima, Léia C. L. Fávaro, Fabricio Machado and Sílvia B. Gonçalves
Fermentation 2022, 8(10), 477; https://0-doi-org.brum.beds.ac.uk/10.3390/fermentation8100477 - 22 Sep 2022
Cited by 2 | Viewed by 1888
Abstract
A lactic-acid-producing strain was isolated from the Brazilian Cerrado soil (Brazilian savanna). Glycerol, a byproduct of the biodiesel industry, can be converted into various chemical intermediates of industrial value by biotechnological routes. Klebsiella pneumoniae can metabolize glycerol in environments with or without oxygen [...] Read more.
A lactic-acid-producing strain was isolated from the Brazilian Cerrado soil (Brazilian savanna). Glycerol, a byproduct of the biodiesel industry, can be converted into various chemical intermediates of industrial value by biotechnological routes. Klebsiella pneumoniae can metabolize glycerol in environments with or without oxygen and bioconvert it into several chemicals with high value-added, such as lactic acid, 3-hydroxypropionic acid and 1,3 propanediol. The wild-type bacterial strain (2GPP) isolated from a soil sample from the Brazilian Cerrado was determined to be a K. pneumoniae complex that was capable of successfully metabolizing glycerol. Fermentations were performed with different temperatures, pH, and inoculum concentrations to evaluate the best lactic acid production. At first, 1,3-propanediol and L-(+)-lactic acid were produced in mini reactors. A lactic acid production of 3.8 g·L−1 and a decrease in 1,3-propanediol output were observed. Thus, by adjusting process variables such as pH and temperature during fermentation, it was possible to maximize the production of lactic acid and decrease the formation of 1,3-propanediol by utilizing experimental design strategies. Full article
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15 pages, 522 KiB  
Article
Effects of Adding Ethanol Extract of Propolis on the Fermentation Quality, Aerobic Stability, Fatty Acid Profile, and In Vitro Digestibility of Alfalfa Silages
by Sibel Soycan Önenç, Banu Yücel and Aslı Turan Uçman
Fermentation 2022, 8(8), 412; https://0-doi-org.brum.beds.ac.uk/10.3390/fermentation8080412 - 21 Aug 2022
Viewed by 1562
Abstract
This study was planned to determine the effects of ethanol extract of propolis on the fermentation quality, fatty acid profile, aerobic stability, and in vitro digestibility of alfalfa silages. The ethanol extract of propolis was added to alfalfa at levels of 1000 mg/kg [...] Read more.
This study was planned to determine the effects of ethanol extract of propolis on the fermentation quality, fatty acid profile, aerobic stability, and in vitro digestibility of alfalfa silages. The ethanol extract of propolis was added to alfalfa at levels of 1000 mg/kg (PROP1), 2000 mg/kg (PROP2), and 3000 mg/kg (PROP3); propolis was not added to the control (CON) group. After the propolis was added, the pH value of the alfalfa silage declined, and the crude protein content was effectively preserved (p < 0.05). Adding propolis to alfalfa silages caused crude fiber, neutral detergent fiber, and acid detergent fiber (p < 0.05) to decrease. The ethanol extract of propolis significantly improved the lactic acid content and reduced the NH3-N content (p < 0.05). Propolis significantly improved the unsaturated fatty acid content (p < 0.05) and reduced the saturated fatty acid content (p < 0.05). In addition, propolis significantly improved the relative feed value, the digestibility of the organic matter, and the in vitro metabolic energy content (p < 0.05). These results show that the ethanol extract of propolis improves the silage quality of last cutting alfalfa silages, and has potential as an antimicrobial silage additive. Full article
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20 pages, 6969 KiB  
Article
The Use of Baikal Psychrophilic Actinobacteria for Synthesis of Biologically Active Natural Products from Sawdust Waste
by Ekaterina V. Pereliaeva, Maria E. Dmitrieva, Maria M. Morgunova, Alexander Y. Belyshenko, Natalia A. Imidoeva, Alexander S. Ostyak and Denis V. Axenov-Gribanov
Fermentation 2022, 8(5), 213; https://0-doi-org.brum.beds.ac.uk/10.3390/fermentation8050213 - 06 May 2022
Cited by 5 | Viewed by 2466
Abstract
One of the relevant areas in microbiology and biotechnology is the study of microorganisms that induce the destruction of different materials, buildings, and machines and lead to negative effects. At the same time, the positive ecological effects of degradation can be explained by [...] Read more.
One of the relevant areas in microbiology and biotechnology is the study of microorganisms that induce the destruction of different materials, buildings, and machines and lead to negative effects. At the same time, the positive ecological effects of degradation can be explained by the detoxication of industrial and agricultural wastes, chemical substances, petroleum products, xenobiotics, pesticides, and other chemical pollutants. Many of these industrial wastes include hard-to-degrade components, such as lignocellulose or plastics. The biosynthesis of natural products based on the transformation of lignocellulosic wastes is of particular interest. One of the world’s unique ecosystems is presented by Lake Baikal. This ecosystem is characterized by the highest level of biodiversity, low temperatures, and a high purity of the water. Here, we studied the ability of several psychrophilic representatives of Baikal Actinobacteria to grow on sawdust wastes and transform them into bioactive natural products. Different strains of both widely spread genus of Actinobacteria and rare genera of Actinobacteria were tested. We used the LC-MS methods to show that Actinobacteria living in sawmill wastes can produce both known and novel natural products with antibiotic activity. We demonstrated that the type of sawmill wastes and their concentration influence the Actinobacteria biosynthetic potential. We have shown for the first time that the use of Baikal psychrophilic microorganisms as a factory for biodegradation is applicable for the transformation of lignocellulosic wastes. Thus, the development of techniques for screening novel natural products leads to an elaboration on the active ingredients for novel drugs. Full article
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Review

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24 pages, 2437 KiB  
Review
The Measurement, Application, and Effect of Oxygen in Microbial Fermentations: Focusing on Methane and Carboxylate Production
by Jose Antonio Magdalena, Largus T. Angenent and Joseph G. Usack
Fermentation 2022, 8(4), 138; https://0-doi-org.brum.beds.ac.uk/10.3390/fermentation8040138 - 22 Mar 2022
Cited by 9 | Viewed by 4548
Abstract
Oxygen is considered detrimental to anaerobic fermentation processes by many practitioners. However, deliberate oxygen sparging has been used successfully for decades to remove H2S in anaerobic digestion (AD) systems. Moreover, microaeration techniques during AD have shown that small doses of oxygen [...] Read more.
Oxygen is considered detrimental to anaerobic fermentation processes by many practitioners. However, deliberate oxygen sparging has been used successfully for decades to remove H2S in anaerobic digestion (AD) systems. Moreover, microaeration techniques during AD have shown that small doses of oxygen may enhance process performance and promote the in situ degradation of recalcitrant compounds. However, existing oxygen dosing techniques are imprecise, which has led to inconsistent results between studies. At the same time, real-time oxygen fluxes cannot be reliably quantified due to the complexity of most bioreactor systems. Thus, there is a pressing need for robust monitoring and process control in applications where oxygen serves as an operating parameter or an experimental variable. This review summarizes and evaluates the available methodologies for oxygen measurement and dosing as they pertain to anaerobic microbiomes. The historical use of (micro-)aeration in anaerobic digestion and its potential role in other anaerobic fermentation processes are critiqued in detail. This critique also provides insights into the effects of oxygen on these microbiomes. Our assessment suggests that oxygen dosing, when implemented in a controlled and quantifiable manner, could serve as an effective tool for bioprocess engineers to further manipulate anaerobic microbiomes for either bioenergy or biochemical production. Full article
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