Studies on delignification in jute (Corchorus spp L.) fibre with promising lignin degrading bacterial isolates

Aim: To investigate the reduction of lignin content in jute (Corchorus spp. L.) with promising lignin degrading bacterial isolates.Methodology: Promising lignin degrading bacterial isolates were screened on the basis of potency index, MnP (manganese peroxidase) and LiP (lignin peroxidase) activities. Very efficient ligninolytic isolates were used for laboratory scale delignification trial and the resultant fibre was tested for lignin content, fibre strength and fineness. The efficient isolates were identified up to species level with Biolog Inc. based on the metabolic fingerprinting of the isolates. Results: Out of 95 ligninolytic bactetial isolates, twenty isolates having potency index >1.10 on the basis of Azure-B dye degradation test were selected for enzyme assays. Five promising isolates (L3, L9, L10, L26 and L30) were selected for delignification trial on the basis of high MnP (126 – 482 U l-1 min-1), and LiP (558.7 – 615.6 U l-1 min-1) activities. The isolate L9 performed best among the five isolates and could reduce lignin content from 11.33 to 8.84% i.e. a reduction of 21.97% from the control. All the five isolates were identified as Bacillus spp. Interpretation: Delignification of jute by using lignin degrading bacteria without any environmental hazard may be considered as an alternate method of chemical delignification for minimization of environmental pollution

Improvement of Delignification, Desilication and Cellulosic Content Availability in Paddy Straw via Physico-chemical Pretreatments

Aim: Paddy straw consists of cellulose and hemicellulose as their plant materials leading to their potential to produce bioethanol through several processes such as pretreatment, enzymatic hydrolysis and ethanol fermentation. Among these processes, pretreatment of paddy straw is particularly important for enzymatic hydrolysis process as they are being limited by the presence of ash and silica content. This study was set to observe the effect of different pretreatments on cellulose, hemicellulose, lignin and ash content of paddy straw. Place and Duration of Study: This study was conducted in Department of Biology, Faculty of Science, Universiti Putra Malaysia, between October 2015 and June 2016. Methodology: Pretreatments comprises the combination of physical (mechanical) and chemical treatments to modify the lignocellulosic structure while reduce lignin and separate silica content in paddy straw fibre. Paddy straw was prepared into three different sizes (2mm, 5mm and 8 mm) for physical treatment. Autoclave, boiled and four different concentrations (0.5%, 1%, 2% and 5% (v/v) and (w/v) respectively) of nitric acid and sodium hydroxide, respectively for chemical treatment were used on paddy straw. Results: Size five millimeter paddy straw showed the highest cellulose content (35.61%) compared to the other sizes and when the paddy pretreated with 2% (w/v) sodium hydroxide (NaOH), the percentage of cellulose content escalated to 72.47%. Pretreatment of 2% (w/v) NaOH have performed the most efficient delignification and desilication process (1.02% lignin; 5.44 ash content); and the performance was supported with SEM images on surface area of the paddy straw with large distortion caused by the treatment. Conclusion: Therefore, a physico-chemical pretreatment of size 5 mm and 2% (w/v) NaOH was found to be the most suitable condition to break the cellulose-lignin complex and make the paddy straw becomes feasible for biofuel production.

Bio-bleaching of Anthocephalus cadamba Kraft Pulp through Direct Fungal Treatment by FEQP Sequence.

Aims: The study aims at mitigating pulp kappa number before bleaching to minimize pollution load. Study Design: An experimental study. Methodology: The various parameters of direct fungal (Coprinellus disseminatus MLK01) treatment (F-stage) of unbleached kraft pulp of Anthocephalus cadamba were optimized and compared with the results of enzymatically pre-bleaching. Finally, the pulp was bleached by EQP three-stage and XECEHH six stages bleaching sequences. Results: Direct fungal treatment (F-stage) delignified the Anthocephalus cadamba kraft pulp more selectively with Coprinellus disseminatus MLK01 compared to xylanase prebleached pulp from the same fungus and oxygen delignification. F-stage mitigated the unbleached pulp kappa number by 55.0% and improved brightness and viscosity by 17.3 and 7.63% respectively. Kappa number reduction and brightness improvement were 22.1 and 6.3% more in F-stage compared to XE-stage. The kappa number and pulp brightness of oxygen delignified were 0.9 and 5.2% less compared to F-stage. The viscosity of oxygen delignified pulp reduced drastically due to alkaline peeling reactions compared to XE-stage (‒26.86%) and F-stage (‒27.09%). The brightness and viscosity of XECEHH bleached pulp were 80.1% and 7.4 cps at a chlorine demand of 4.3% while FEQP bleached pulp produced brightness of 79.7% and viscosity 8.2 cps. COD and colour values in effluent generated during FEQP bleaching were 53.29% and 54.36% less compared to CEHH bleaching.

Pretreatment strategies for delignification of sugarcane bagasse: a review

The valorization of agro-residues by biological routes is a key technology that contributes to the development of sustainable processes and the generation of value-added products. Sugarcane bagasse is an agro-residue generated by the sugar and alcohol industry in Brazil (186 million tons per year), composed essentially of cellulose (32-44%), hemicellulose (27-32%) and lignin (19-24%). The conversion of sugarcane bagasse into fermentable sugars requires essentially two steps: pretreatment and hydrolysis. The aim of the pretreatment is to separate the lignin and break the structure of lignocellulose, and it is one of the most critical steps in the process of converting biomass to fermentable sugars. The aim of this review is to describe different pretreatment strategies to promote the delignification of the sugarcane bagasse by thermo-chemical and biological processes.

Caracterización de actinobacterias raras, degradadoras de lignocelulosa: demostración de actividad lacasa en dos aislados de Tsukamurella sp y Cellulosimicrobium sp / Characterization of lignocellulose-degrading rare actinobacteria: demostration of laccase activity in two isolates of Tsukamurella sp and Cellulosimicrobium sp

Las características fisicoquímicas de la lignina y su compactación con la celulosa han dificultado la explotación biotecnológica de enormes cantidades de biomasa vegetal. Las lacasas constituyen una subfamilia de oxidasas multicobre que intervienen en la despolimerización de la lignina. Si bien han sido ampliamente caracterizadas en los hongos, los estudios de la diversidad y las funcionalidades de las lacasas en los procariotas se han centrado especialmente en isoformas enzimáticas de Streptomyces sp. En este trabajo se aislaron 20 cepas de actinobacterias del suelo. La actividad lacasa de 17 de ellas fue evidenciada en ensayos cualitativos con guayacol y dos cepas seleccionadas fueron caracterizadas en detalle. Las pruebas morfológicas y el análisis de las secuencias del gen 16S rRNA apuntan a que estos dos aislados pertenecen a los géneros Tsukamurella y Cellulosimicrobium. En cultivo sumergido con agitación, AC01 (Tsukamurella sp.) expresó una máxima actividad de oxidación de ABTS (2,2’-azino-bis-(3-etilbenzotiazolin-6-sulfonato) de 108 U/L. Por otra parte, AC18 (Cellulosimicrobium sp.) que había exhibido una actividad oxidativa de guayacol superior a las 16 cepas restantes y demostró ser resistente a niveles tóxicos de cobre, logró un valor máximo de oxidación del ABTS de 0,56 U/L. Estos resultados sugieren que en el aislado AC18 operaría un fenómeno de especificidad de sustrato o de inductor, regulador de la expresión y de la actividad lacasa cuantificable. La caracterización genómica y funcional de las lacasas de nuevas actinobacterias lignocelulósicas ampliará la gama de centros redox con aplicaciones biotecnológicas específicas, además de facilitar el establecimiento de sus relaciones evolutivas con las eucariotas.

The physicochemical characteristics of lignin and its compaction with cellulose have restricted the biotechnological exploitation of enormous amounts of plant biomass. Laccases are a subfamily of multicopper oxidases involved in lignin depolymerization. Although they have been extensively characterized in fungi, studies of the diversity and functions of laccases in prokaryotes are mainly on enzyme isoforms of Streptomyces sp. In this work we isolated 20 strains of soil actinomycetes. The laccase activity of 17 of them was evidenced in qualitative assays with guaiacol, and two selected strains were characterized in detail. The morphological evidence and the analysis of the 16S rRNA gene sequences suggest that these two isolates belong to the genera Tsukamurella and Cellulosimicrobium. In submerged cultures with shaking, AC01 (Tsukamurella sp.) exhibited a maximal oxidation activity of ABTS (2,2 '-azino-bis-(3-ethylbenzthiazoline-6-sulfonate) of 108 U/L. On the other hand, AC18 (Cellulosimicrobium sp.) that exhibited a higher oxidative activity of guaiacol than the other 16 isolated strains and showed resistance to toxic levels of copper, reached a maximum ABTS oxidation rate of 0.56 U/L. These results suggest that in AC18 operates a mechanism of substrate or inducer specificity, regulating the measurable laccase activity and laccase gene expression. Genomic and functional characterization of laccases of new ligninolytic actinomycetes may help to extend the range of redox centers with specific biotechnological applications, as well as establishing their evolutionary relationships with eukaryotes.

An environmentally friendly organosolv (ethanol-water) pulping of poplar wood.

In this study, pulp production from the fast growing plant, poplar, was examined for organosolv pulping with or without catalysts. In order to find the optimum cooking conditions, 18 different cooking experiments were carried out. The effect of ethanol ratio, cooking time as well as catalyst was studied. It was observed that even at lower temperature (90oC), cooking without catalyst was able to cause sufficient defiberization. It was seen that the increasing proportion of catalyst and cooking temperature resulted in an increased delignification. However in the case of using 0.02% acid catalyst pulp yield and viscosity were lowered to an unacceptable level. The most important cooking factors were found to be the proportion of acid catalyst. Furthermore, the delignification performance was found to be depending on the pH of the black liquor. In a result, the optimum pulp properties were obtained by cooking at 180oC for 90 min with 50 % ethanol mixture without catalyst. The pulp yield was noted as 44.49 %, viscosity was 892 cm2 g-1 and the kappa number was 67.