Lime pretreatment of sugar beet pulp and evaluation of synergy between ArfA, ManA and XynA from Clostridium cellulovorans on the pretreated substrate

Expression profiling of Clostridium thermocellum B8 during the deconstruction of sugarcane bagasse and straw

The gram-positive bacterium Clostridium thermocellum contains a set of carbohydrate-active enzymes that can potentially be employed to generate high-value-added products from lignocellulose. In this study, the gene expression profiling of C. thermocellum B8 was provided during growth in the presence of sugarcane bagasse and straw as a carbon source in comparison to growth using microcrystalline cellulose. A total of 625 and 509 genes were up-regulated for growth in the presence of bagasse and straw, respectively. These genes were mainly grouped into carbohydrate-active enzymes (CAZymes), cell motility, chemotaxis, quorum sensing pathway and expression control of glycoside hydrolases. These results show that type of carbon source modulates the gene expression profiling of carbohydrate-active enzymes. In addition, highlight the importance of cell motility, attachment to the substrate and communication in deconstructing complex substrates. This present work may contribute to the development of enzymatic cocktails and industrial strains for biorefineries based on sugarcane residues as feedstock.

Enzymatic Characterization of Unused Biomass Degradation Using the Clostridium cellulovorans Cellulosome

The cellulolytic system of Clostridium cellulovorans mainly consisting of a cellulosome that synergistically collaborates with non-complexed enzymes was investigated using cellulosic biomass. The cellulosomes were isolated from the culture supernatants with shredded paper, rice straw and sugarcane bagasse using crystalline cellulose. Enzyme solutions, including the cellulosome fractions, were analyzed by SDS-PAGE and Western blot using an anti-CbpA antibody. As a result, C. cellulovorans was able to completely degrade shredded paper for 9 days and to be continuously cultivated by the addition of new culture medium containing shredded paper, indicating, through TLC analysis, that its degradative products were glucose and cellobiose. Regarding the rice straw and sugarcane bagasse, while the degradative activity of rice straw was most active using the cellulosome in the culture supernatant of rice straw medium, that of sugarcane bagasse was most active using the cellulosome from the supernatant of cellobiose medium. Based on these results, no alcohols were found when C. acetobutylicum was cultivated in the absence of C. cellulovorans as it cannot degrade the cellulose. While 1.5 mM of ethanol was produced with C. cellulovorans cultivation, both n-butanol (1.67 mM) and ethanol (1.89 mM) were detected with the cocultivation of C. cellulovorans and C. acetobutylicum. Regarding the enzymatic activity evaluation against rice straw and sugarcane bagasse, the rice straw cellulosome fraction was the most active when compared against rice straw. Furthermore, since we attempted to choose reaction conditions more efficiently for the degradation of sugarcane bagasse, a wet jet milling device together with L-cysteine as a reducing agent was used. As a result, we found that the degradation activity was almost twice as high with 10 mM L-cysteine compared with without it. These results will provide new insights for biomass utilization.

Combination of Antimicrobial Starters for Feed Fermentation: Influence on Piglet Feces Microbiota and Health and Growth Performance, Including Mycotoxin Biotransformation in vivo

The aim of this study was to apply a combination of the microbial starters Lactobacillus uvarum LUHS245, Lactobacillus casei LUHS210, Pediococcus acidilactici LUHS29, and Pediococcus pentosaceus LUHS183 for feed fermentation and to evaluate the influence of fermentation on feed acidity and microbiological characteristics, as well as on the piglet feces microbiota, health, and growth performance. Additionally, mycotoxin biotransformation was analyzed, including masked mycotoxins, in feed and piglet feces samples. The 36-day experiment was conducted using 25-day-old Large White/Norwegian Landrace (LW/NL) piglets with an initial body weight of 6.9–7.0 kg, which were randomly distributed into two groups (in each 100 piglets): control group, fed with basal diet (based on barley, wheat, potato protein, soybean protein concentrate, and whey powder), and treated group, fed with fermented feed at 500 g kg⁻¹ of total feed. Compared to a commercially available lactic acid bacteria (LAB) combination, the novel LAB mixture effectively reduced feed pH (on average pH 3.65), produced a 2-fold higher content of L(+) lactic acid, increased viable LAB count [on average 8.8 log₁₀ colony-forming units (CFU) g⁻¹], and led to stable feed fermentation during the entire test period (36 days). Fecal microbiota analysis showed an increased number of probiotic bacteria in the treated group, particularly Lactobacillus, when compared with the control group at the end of experiment. This finding indicates that fermented feed can modify microbial profile change in the gut of pigs. In treated piglets' blood (at day 61), the serum high-density lipoprotein (HDL) cholesterol and triglycerides (TG) were significantly higher, but the levels of T4, glucose, K, alkaline phosphatase (AP), and urea were significantly decreased (p ≤ 0.05) compared with the control group. Mycotoxin analysis showed that alternariol monomethyl ether (AME) and altenuene were found in 61-day-old control piglets' feces and in fermented feed samples. However, AME was not found in treated piglets' feces. Feed fermentation with the novel LAB combination is a promising means to modulate piglets' microbiota, which is essential to improve nutrient absorption, growth performance, and health parameters. The new LAB composition suggests a novel dietary strategy to positively manipulate fermented feed chemicals and bio-safety and the piglet gut microbial ecology to reduce antimicrobials use in pig production and increase local feed stock uses and economical effectiveness of the process.

The Second-Generation Biomethane from Mandarin Orange Peel under Cocultivation with Methanogens and the Armed Clostridium cellulovorans

This study demonstrates that the consortium, which consists of the microbial flora of methane production (MFMP) and Clostridium cellulovorans grown with cellulose, can perform the direct conversion of cellulosic biomass to methane. The MFMP was taken from a commercial methane fermentation tank and was extremely complicated. Therefore, C. cellulovorans grown with cellobiose could not perform high degradation ability on cellulosic biomass due to competition by various microorganisms in MFMP. Focusing on the fact that C. cellulovorans was cultivated with cellulose, which is armed with cellulosome, so that it is now armed C. cellulovorans; the direct conversion was carried out by the consortium which consisted of MFMP and the armed C. cellulovorans. As a result, the consortium of C. cellulovorans grown with cellobiose and MFMP (CCeM) could not degrade the purified cellulose and mandarin orange peel. However, MFMP and the armed C. cellulovorans reduced 78.4% of the total sugar of the purified cellulose such as MN301, and produced 6.89 mL of methane simultaneously. Furthermore, the consortium consisted of MFMP and the armed C. cellulovorans degraded mandarin orange peel without any pretreatments and produced methane that was accounting for 66.2% of the total produced gas.

Biomethane production from sugar beet pulp under cocultivation with Clostridium cellulovorans and methanogens

This study was demonstrated with a coculture fermentation system using sugar beet pulp (SBP) as a carbon source combining the cellulose-degrading bacterium Clostridium cellulovorans with microbial flora of methane production (MFMP) for the direct conversion of cellulosic biomass to methane (CH₄). The MFMP was taken from a commercial methane fermentation plant and extremely complicated. Therefore, the MFMP was analyzed by a next-generation sequencing system and the microbiome was identified and classified based on several computer programs. As a result, Methanosarcina mazei (1.34% of total counts) and the other methanogens were found in the MFMP. Interestingly, the simultaneous utilization of hydrogen (H₂) and carbon dioxide (CO₂) for methanogenesis was observed in the coculture with Consortium of C. cellulovorans with the MFMP (CCeM) including M. mazei. Furthermore, the CCeM degraded 87.3% of SBP without any pretreatment and produced 34.0 L of CH₄ per 1 kg of dry weight of SBP. Thus, a gas metabolic shift in the fermentation pattern of C. cellulovorans was observed in the CCeM coculture. These results indicated that degradation of agricultural wastes was able to be carried out simultaneously with CH₄ production by C. cellulovorans and the MFMP.

A review of lignocellulose bioconversion using enzymatic hydrolysis and synergistic cooperation between enzymes--factors affecting enzymes, conversion and synergy

Lignocellulose is a complex substrate which requires a variety of enzymes, acting in synergy, for its complete hydrolysis. These synergistic interactions between different enzymes have been investigated in order to design optimal combinations and ratios of enzymes for different lignocellulosic substrates that have been subjected to different pretreatments. This review examines the enzymes required to degrade various components of lignocellulose and the impact of pretreatments on the lignocellulose components and the enzymes required for degradation. Many factors affect the enzymes and the optimisation of the hydrolysis process, such as enzyme ratios, substrate loadings, enzyme loadings, inhibitors, adsorption and surfactants. Consideration is also given to the calculation of degrees of synergy and yield. A model is further proposed for the optimisation of enzyme combinations based on a selection of individual or commercial enzyme mixtures. The main area for further study is the effect of and interaction between different hemicellulases on complex substrates.