1
|
Bautista-Cruz A, Aquino-Bolaños T, Hernández-Canseco J, Quiñones-Aguilar EE. Cellulolytic Aerobic Bacteria Isolated from Agricultural and Forest Soils: An Overview. BIOLOGY 2024; 13:102. [PMID: 38392320 PMCID: PMC10886624 DOI: 10.3390/biology13020102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Revised: 01/29/2024] [Accepted: 01/31/2024] [Indexed: 02/24/2024]
Abstract
This review provides insights into cellulolytic bacteria present in global forest and agricultural soils over a period of 11 years. It delves into the study of soil-dwelling cellulolytic bacteria and the enzymes they produce, cellulases, which are crucial in both soil formation and the carbon cycle. Forests and agricultural activities are significant contributors to the production of lignocellulosic biomass. Forest ecosystems, which are key carbon sinks, contain 20-30% cellulose in their leaf litter. Concurrently, the agricultural sector generates approximately 998 million tons of lignocellulosic waste annually. Predominant genera include Bacillus, Pseudomonas, Stenotrophomonas, and Streptomyces in forests and Bacillus, Streptomyces, Pseudomonas, and Arthrobacter in agricultural soils. Selection of cellulolytic bacteria is based on their hydrolysis ability, using artificial cellulose media and dyes like Congo red or iodine for detection. Some studies also measure cellulolytic activity in vitro. Notably, bacterial cellulose hydrolysis capability may not align with their cellulolytic enzyme production. Enzymes such as GH1, GH3, GH5, GH6, GH8, GH9, GH10, GH12, GH26, GH44, GH45, GH48, GH51, GH74, GH124, and GH148 are crucial, particularly GH48 for crystalline cellulose degradation. Conversely, bacteria with GH5 and GH9 often fail to degrade crystalline cellulose. Accurate identification of cellulolytic bacteria necessitates comprehensive genomic analysis, supplemented by additional proteomic and transcriptomic techniques. Cellulases, known for degrading cellulose, are also significant in healthcare, food, textiles, bio-washing, bleaching, paper production, ink removal, and biotechnology, emphasizing the importance of discovering novel cellulolytic strains in soil.
Collapse
Affiliation(s)
- Angélica Bautista-Cruz
- Instituto Politécnico Nacional, CIIDIR-Oaxaca, Hornos 1003, Santa Cruz Xoxocotlán 71230, Oaxaca, Mexico
| | - Teodulfo Aquino-Bolaños
- Instituto Politécnico Nacional, CIIDIR-Oaxaca, Hornos 1003, Santa Cruz Xoxocotlán 71230, Oaxaca, Mexico
| | - Jessie Hernández-Canseco
- Doctoral Programme in Conservation and Use of Natural Resources, Instituto Politécnico Nacional, CIIDIR-Oaxaca, Hornos 1003, Santa Cruz Xoxocotlán 71230, Oaxaca, Mexico
| | - Evangelina Esmeralda Quiñones-Aguilar
- Laboratorio de Fitopatología de Biotecnología Vegetal, Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco, A.C. Camino Arenero 1227, El Bajío del Arenal, Zapopan 45019, Jalisco, Mexico
| |
Collapse
|
2
|
Determining Cellulolytic Activity of Microorganisms. CHEMISTRY-DIDACTICS-ECOLOGY-METROLOGY 2021. [DOI: 10.2478/cdem-2020-0010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Abstract
Decomposition of cellulose to glucose requires complex cooperation of glycoside hydrolase enzymes. As a result of glycoside β-1,4 bonds hydrolysis, shorter chains of cellulose, oligodextrin, cellobiose and glucose are created. A number of bacteria and fungi demonstrate the capacity to degrade cellulose. Their activity can be assessed with the use of qualitative and quantitative methods. Qualitative methods with the use of e.g. Congo red, are used in screening studies, however, they do not provide information about the quantity of the produced enzyme. Spectrophotometric methods are more accurate and they measure the quantities of reducing sugars with the use of appropriate substrates, e.g. carboxymethylcellulose is used to determine endoglucanases, avicel cellulose to determine exoglucanases and Whatman filter paper to determine total cellulolytic activity. Activity of microorganisms depends not only on their species or type but also, among others, on substratum composition, cultivation conditions and the appropriate selection of parameters of the carried out enzymatic reactions.
Collapse
|
3
|
Hero JS, Pisa JH, Raimondo EE, Martínez MA. Proteomic analysis of secretomes from Bacillus sp. AR03: characterization of enzymatic cocktails active on complex carbohydrates for xylooligosaccharides production. Prep Biochem Biotechnol 2021; 51:871-880. [PMID: 33439095 DOI: 10.1080/10826068.2020.1870136] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Bacillus sp. AR03 have been described as an important producer of carbohydrate-active enzymes (CAZymes) when growing in a peptone-based medium supplemented with simple sugars and/or carboxymethyl cellulose (CMC) as carbon sources. This work aimed to identify the extracellular enzymatic cocktails through shotgun proteomics. The proteomic analysis showed that enzymes involved in cellulose and xylan degradation were among the most abundant proteins. These enzymes included an endo-glucanase GH5_2 and a glucuronoxylanase GH30_8, which were found in all conditions. In addition, several proteins were differentially expressed in the three evaluated culture media, indicating microbial metabolic changes due to the different supplied carbon sources, particularly, in the presence of CMC. Finally, the capability of the crude enzymatic cocktails from culture media to degrade birchwood xylan was assessed, which produced mostly xylooligosaccharides containing among 3-5 xylose units. Consequently, this work shows the potential of the extracellular enzymes from Bacillus sp. AR03 for producing emergent prebiotics.
Collapse
Affiliation(s)
- Johan S Hero
- Planta Piloto de Procesos Industriales Microbiológicos (PROIMI), CONICET, Tucumán, Argentina
| | - José H Pisa
- Planta Piloto de Procesos Industriales Microbiológicos (PROIMI), CONICET, Tucumán, Argentina
| | - Enzo E Raimondo
- Planta Piloto de Procesos Industriales Microbiológicos (PROIMI), CONICET, Tucumán, Argentina.,Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, Tucumán, Argentina
| | - M Alejandra Martínez
- Planta Piloto de Procesos Industriales Microbiológicos (PROIMI), CONICET, Tucumán, Argentina.,Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán, Tucumán, Argentina
| |
Collapse
|
4
|
Mukherjee S, Behera PK, Madhuprakash J. Efficient conversion of crystalline chitin to N-acetylglucosamine and N,N'-diacetylchitobiose by the enzyme cocktail produced by Paenibacillus sp. LS1. Carbohydr Polym 2020; 250:116889. [DOI: 10.1016/j.carbpol.2020.116889] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 07/31/2020] [Accepted: 08/03/2020] [Indexed: 12/20/2022]
|
5
|
Rodrigues IDSV, Barreto JT, Moutinho BL, Oliveira MMG, da Silva RS, Fernandes MF, Fernandes RPM. Production of xylanases by Bacillus sp. TC-DT13 in solid state fermentation using bran wheat. Prep Biochem Biotechnol 2019; 50:91-97. [PMID: 31517567 DOI: 10.1080/10826068.2019.1663536] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Xylanases have gained increasing importance due to their diverse applications in the food, paper, and pharmaceutical industries, however, the production of these enzymes currently uses expensive substrates. It has already been estimated that more than 30% of the enzyme production cost originates from the substrate. The present study aimed to optimize the production of extracellular xylanases by the Bacillus sp. TC-DT 13 using solid-state fermentation with agro-industrial residues, with a view at reducing the production cost of these enzymes. All the agro-industrial residues were tested in submerged fermentation to select the best inductor to produce xylanase. Among these residues, wheat bran was selected as the best inducer of xylanase production with 1500 U/mL. Regarding solid-state fermentation, the use of wheat bran as the only fermentation substrate was used and a ratio of 1:4 moisture over a time of 144 hours induced higher amount of xylanase reaching 2943 U/g. The use of carbon and nitrogen sources did not result in the increase in production of xylanolitic enzymes. The use of agro-industrial residues in the solid-state fermentation, besides increasing the production of xylanase, reduces the cost of production and is an environmentally friendly alternative.
Collapse
Affiliation(s)
| | - Jessyca Teles Barreto
- Departamento de Fisiologia, Laboratório de Enzimologia, Universidade Federal de Sergipe (UFS), Sergipe, Brazil
| | - Brenda Leite Moutinho
- Departamento de Fisiologia, Laboratório de Enzimologia, Universidade Federal de Sergipe (UFS), Sergipe, Brazil
| | | | - Rafael Salomão da Silva
- Departamento de Fisiologia, Laboratório de Enzimologia, Universidade Federal de Sergipe (UFS), Sergipe, Brazil
| | | | | |
Collapse
|
6
|
Neelkant KS, Shankar K, Jayalakshmi SK, Sreeramulu K. Optimization of conditions for the production of lignocellulolytic enzymes by Sphingobacterium sp. ksn-11 utilizing agro-wastes under submerged condition. Prep Biochem Biotechnol 2019; 49:927-934. [PMID: 31318309 DOI: 10.1080/10826068.2019.1643735] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The present work was aimed at studying the production of lignocellulolytic enzymes, namely cellulase, xylanase, pectinase, mannanase, and laccase by a newly isolated bacterium Sphingobacterium sp. ksn-11, utilizing various agro-residues as a substrate under submerged conditions. The production of lignocellulolytic enzymes was found to be maximum at the loading of 10%(w/v) agro-residues. The enzyme secretion was enhanced by two-fold at 2 mM CaCO3, optimum pH 7, and temperature 40°. The Field Emission Gun-Scanning Electron Microscope (FEG-SEM) results have shown the degradative effect of lignocellulases; cellulase, xylanase, mannanase, pectinase, and laccase on corn husk with 3.55 U/ml, 79.22 U/ml, 12.43 U/ml, 64.66 U/ml, and 21.12 U/ml of activity, respectively. The hydrolyzed corn husk found to be good adsorbent for polyphenols released during hydrolysis of corn husk providing suitable conditions for stability of lignocellulases. Sphingobacterium sp. ksn is proved to be a promising candidate for lignocellulolytic enzymes in view of demand for enzymes in the biofuel industry.
Collapse
Affiliation(s)
| | - Kumar Shankar
- Department of Biochemistry, Gulbarga University , Kalaburagi , India
| | - S K Jayalakshmi
- Agricultural college (University of agricultural sciences-Raichur) , Kalaburagi , India
| | - Kuruba Sreeramulu
- Department of Biochemistry, Gulbarga University , Kalaburagi , India
| |
Collapse
|
7
|
Chen L, Gu W, Xu HY, Yang GL, Shan XF, Chen G, Wang CF, Qian AD. Complete genome sequence of Bacillus velezensis 157 isolated from Eucommia ulmoides with pathogenic bacteria inhibiting and lignocellulolytic enzymes production by SSF. 3 Biotech 2018; 8:114. [PMID: 29430375 PMCID: PMC5801104 DOI: 10.1007/s13205-018-1125-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2017] [Accepted: 01/16/2018] [Indexed: 10/18/2022] Open
Abstract
Bacillus velezensis 157 was isolated from the bark of Eucommia ulmoides, and exhibited antagonistic activity against a broad spectrum of pathogenic bacteria and fungi. Moreover, B. velezensis 157 also showed various lignocellulolytic activities including cellulase, xylanase, α-amylase, and pectinase, which had the ability of using the agro-industrial waste (soybean meal, wheat bran, sugarcane bagasse, wheat straw, rice husk, maize flour and maize straw) under solid-state fermentation and obtained several industrially valuable enzymes. Soybean meal appeared to be the most efficient substrate for the single fermentation of B. velezensis 157. Highest yield of pectinase (19.15 ± 2.66 U g-1), cellulase (46.69 ± 1.19 U g-1) and amylase (2097.18 ± 15.28 U g-1) was achieved on untreated soybean meal. Highest yield of xylanase (22.35 ± 2.24 U g-1) was obtained on untreated wheat bran. Here, we report the complete genome sequence of the B. velezensis 157, composed of a circular 4,013,317 bp chromosome with 3789 coding genes and a G + C content of 46.41%, one circular 8439 bp plasmid and a G + C content of 40.32%. The genome contained a total of 8 candidate gene clusters (bacillaene, difficidin, macrolactin, butirosin, bacillibactin, bacilysin, fengycin and surfactin), and dedicates over 15.8% of the whole genome to synthesize secondary metabolite biosynthesis. In addition, the genes encoding enzymes involved in degradation of cellulose, xylan, lignin, starch, mannan, galactoside and arabinan were found in the B. velezensis 157 genome. Thus, the study of B. velezensis 157 broadened that B. velezensis can not only be used as biocontrol agents, but also has potentially a wide range of applications in lignocellulosic biomass conversion.
Collapse
Affiliation(s)
- Long Chen
- College of Animal Science and Technology, Jilin Agricultural University, Changchun, 130118 People’s Republic of China
| | - Wei Gu
- Shandong BaoLai-LeeLai Bioengineering Co. Ltd., Tai’an, 271000 Shandong People’s Republic of China
| | - Hai-yan Xu
- Shandong BaoLai-LeeLai Bioengineering Co. Ltd., Tai’an, 271000 Shandong People’s Republic of China
| | - Gui-Lian Yang
- College of Animal Science and Technology, Jilin Agricultural University, Changchun, 130118 People’s Republic of China
- Jilin Provincial Engineering Research Center of Animal Probiotics, Jilin Agricultural University, Changchun, 130118 People’s Republic of China
- Key Laboratory of Animal Production and Product Quality Safety of Ministry of Education, Jilin Agricultural University, Changchun, 130118 People’s Republic of China
| | - Xiao-Feng Shan
- College of Animal Science and Technology, Jilin Agricultural University, Changchun, 130118 People’s Republic of China
| | - Guang Chen
- College of Life Sciences, Jilin Agricultural University, Changchun, 130118 People’s Republic of China
| | - Chun-Feng Wang
- College of Animal Science and Technology, Jilin Agricultural University, Changchun, 130118 People’s Republic of China
- Jilin Provincial Engineering Research Center of Animal Probiotics, Jilin Agricultural University, Changchun, 130118 People’s Republic of China
- Key Laboratory of Animal Production and Product Quality Safety of Ministry of Education, Jilin Agricultural University, Changchun, 130118 People’s Republic of China
| | - Ai-Dong Qian
- College of Animal Science and Technology, Jilin Agricultural University, Changchun, 130118 People’s Republic of China
- Jilin Provincial Engineering Research Center of Animal Probiotics, Jilin Agricultural University, Changchun, 130118 People’s Republic of China
- Key Laboratory of Animal Production and Product Quality Safety of Ministry of Education, Jilin Agricultural University, Changchun, 130118 People’s Republic of China
| |
Collapse
|
8
|
Pisa JH, Manfredi AP, Perotti NI, Romero HG, Breccia JD, Martínez MA. Agrowastes as Feedstock for the Production of Endo-β-Xylanase from Cohnella sp. Strain AR92. J Mol Microbiol Biotechnol 2017; 27:277-288. [DOI: 10.1159/000480541] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 08/17/2017] [Indexed: 11/19/2022] Open
Abstract
Members of <i>Cohnella </i>sp. isolated from a variety of environments have been shown to be glycoside hydrolase producers. Nevertheless, most evaluations of members of this genus are limited to their taxonomic description. The strain AR92, previously identified as belonging to the genus <i>Cohnella</i>, formed a well-supported cluster with <i>C. thailandensis</i> and <i>C. formosensis</i> (>80% bootstrap confidence). Its growth and xylanase production were approached by using a mineral-based medium containing alkali-pretreated sugarcane bagasse as the main carbon source, which was assayed as a convenient source to produce biocatalysts potentially fitting its degradation. By means of a two-step statistical approach, the production of endoxylanase was moderately improved (20%). However, a far more significant improvement was observed (145%), by increasing the inoculum size and lowering the fermentation temperature to 25°C, which is below the optimal growth temperature of the strain AR92 (37°C). The xylanolytic preparation produced by <i>Cohnella</i> sp. AR92 contained mild temperature-active endoxylanase (identified as redundant GH10 family) for the main activity which resulted in xylobiose and xylo-oligosaccharides as the main products from birchwood xylan.
Collapse
|
9
|
Di Marco E, Soraire PM, Romero CM, Villegas LB, Martínez MA. Raw sugarcane bagasse as carbon source for xylanase production by Paenibacillus species: a potential degrader of agricultural wastes. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2017; 24:19057-19067. [PMID: 28660507 DOI: 10.1007/s11356-017-9494-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 06/07/2017] [Indexed: 06/07/2023]
Abstract
Paenibacillus species isolated from a variety of natural sources have shown to be important glycoside hydrolases producers. These enzymes play a key role in bio-refining applications, as they are central biocatalysts for the processing of different types of polymers from vegetal biomass. Xylanase production by three native isolates belonging to the genus Paenibacillus was approached by utilizing mineral-based medium and agricultural by-products as a convenient source to produce biocatalysts suitable for their degradation. While varieties of alkali pretreated sugarcane bagasse were useful substrates for the strains from Paenibacillus genus evaluated, raw sugarcane bagasse was the most effective substrate for endoxylanase production by Paenibacillus sp. AR247. This strain was then selected to further improvement of its enzyme production by means of a two-step statistical approach. It was determined that the carbon source, provided as an inexpensive agro-waste, as well as phosphate and magnesium were the culture media components that most influenced the enzyme production, which was improved three times compared to the screening results.
Collapse
Affiliation(s)
- Enzo Di Marco
- PROIMI (Planta Piloto de Procesos Industriales Microbiológicos), CONICET, 4000, Tucumán, Argentina
| | - Pablo M Soraire
- PROIMI (Planta Piloto de Procesos Industriales Microbiológicos), CONICET, 4000, Tucumán, Argentina
| | - Cintia M Romero
- PROIMI (Planta Piloto de Procesos Industriales Microbiológicos), CONICET, 4000, Tucumán, Argentina
- Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, 4000, Tucumán, Argentina
| | - Liliana B Villegas
- INQUISAL (Instituto de Química San Luis), CONICET - Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis, 5700, San Luis, Argentina
| | - María Alejandra Martínez
- PROIMI (Planta Piloto de Procesos Industriales Microbiológicos), CONICET, 4000, Tucumán, Argentina.
- Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán, 4000, Tucumán, Argentina.
| |
Collapse
|
10
|
Hero JS, Pisa JH, Perotti NI, Romero CM, Martínez MA. Endoglucanase and xylanase production by Bacillus sp. AR03 in co-culture. Prep Biochem Biotechnol 2017; 47:589-596. [PMID: 28106512 DOI: 10.1080/10826068.2017.1280826] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
The behavior of three isolates retrieved from different cellulolytic consortia, Bacillus sp. AR03, Paenibacillus sp. AR247 and Achromobacter sp. AR476-2, were examined individually and as co-cultures in order to evaluate their ability to produce extracellular cellulases and xylanases. Utilizing a peptone-based medium supplemented with carboxymethyl cellulose (CMC), an increase estimation of 1.30 and 1.50 times was obtained by the co-culture containing the strains AR03 and AR247, with respect to enzyme titles registered by their individual cultivation. On the contrary, the extracellular enzymatic production decreased during the co-cultivation of strain AR03 with the non-cellulolytic Achromobacter sp. AR476-2. The synergistic behavior observed through the combined cultivation of the strains AR03 and AR247 might be a consequence of the consumption by Paenibacillus sp. AR247 of the products of the CMC hydrolysis (i.e., cellobiose and/or cello-oligosaccharides), which were mostly generated by the cellulase producer Bacillus sp. AR03. The effect observed could be driven by the requirement to fulfill the nutritional supply from both strains on the substrate evaluated. These results would contribute to a better description of the degradation of the cellulose fraction of the plant cell walls in nature, expected to an efficient utilization of renewable sources.
Collapse
Affiliation(s)
- Johan S Hero
- a PROIMI Planta Piloto de Procesos Industriales Microbiológicos , CONICET , Tucumán , Argentina
| | - José H Pisa
- a PROIMI Planta Piloto de Procesos Industriales Microbiológicos , CONICET , Tucumán , Argentina
| | - Nora I Perotti
- a PROIMI Planta Piloto de Procesos Industriales Microbiológicos , CONICET , Tucumán , Argentina.,b Facultad de Ciencias Exactas y Tecnología , Universidad Nacional de Tucumán , Tucumán , Argentina
| | - Cintia M Romero
- a PROIMI Planta Piloto de Procesos Industriales Microbiológicos , CONICET , Tucumán , Argentina.,c Facultad de Bioquímica, Química y Farmacia , Universidad Nacional de Tucumán , Tucumán , Argentina
| | - María A Martínez
- a PROIMI Planta Piloto de Procesos Industriales Microbiológicos , CONICET , Tucumán , Argentina.,b Facultad de Ciencias Exactas y Tecnología , Universidad Nacional de Tucumán , Tucumán , Argentina
| |
Collapse
|
11
|
Aulitto M, Fusco S, Bartolucci S, Franzén CJ, Contursi P. Bacillus coagulans MA-13: a promising thermophilic and cellulolytic strain for the production of lactic acid from lignocellulosic hydrolysate. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:210. [PMID: 28904563 PMCID: PMC5590179 DOI: 10.1186/s13068-017-0896-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 08/28/2017] [Indexed: 05/15/2023]
Abstract
BACKGROUND The transition from a petroleum-based economy towards more sustainable bioprocesses for the production of fuels and chemicals (circular economy) is necessary to alleviate the impact of anthropic activities on the global ecosystem. Lignocellulosic biomass-derived sugars are suitable alternative feedstocks that can be fermented or biochemically converted to value-added products. An example is lactic acid, which is an essential chemical for the production of polylactic acid, a biodegradable bioplastic. However, lactic acid is still mainly produced by Lactobacillus species via fermentation of starch-containing materials, the use of which competes with the supply of food and feed. RESULTS A thermophilic and cellulolytic lactic acid producer was isolated from bean processing waste and was identified as a new strain of Bacillus coagulans, named MA-13. This bacterium fermented lignocellulose-derived sugars to lactic acid at 55 °C and pH 5.5. Moreover, it was found to be a robust strain able to tolerate high concentrations of hydrolysate obtained from wheat straw pre-treated by acid-catalysed (pre-)hydrolysis and steam explosion, especially when cultivated in controlled bioreactor conditions. Indeed, unlike what was observed in microscale cultivations (complete growth inhibition at hydrolysate concentrations above 50%), B. coagulans MA-13 was able to grow and ferment in 95% hydrolysate-containing bioreactor fermentations. This bacterium was also found to secrete soluble thermophilic cellulases, which could be produced at low temperature (37 °C), still retaining an optimal operational activity at 50 °C. CONCLUSIONS The above-mentioned features make B. coagulans MA-13 an appealing starting point for future development of a consolidated bioprocess for production of lactic acid from lignocellulosic biomass, after further strain development by genetic and evolutionary engineering. Its optimal temperature and pH of growth match with the operational conditions of fungal enzymes hitherto employed for the depolymerisation of lignocellulosic biomasses to fermentable sugars. Moreover, the robustness of B. coagulans MA-13 is a desirable trait, given the presence of microbial growth inhibitors in the pre-treated biomass hydrolysate.
Collapse
Affiliation(s)
- Martina Aulitto
- Dipartimento di Biologia, Università degli Studi di Napoli Federico II, Naples, Italy
- Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Salvatore Fusco
- Dipartimento di Biologia, Università degli Studi di Napoli Federico II, Naples, Italy
- Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Simonetta Bartolucci
- Dipartimento di Biologia, Università degli Studi di Napoli Federico II, Naples, Italy
| | - Carl Johan Franzén
- Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Patrizia Contursi
- Dipartimento di Biologia, Università degli Studi di Napoli Federico II, Naples, Italy
| |
Collapse
|