Bioconversion of sugar cane crop residues with white-rot fungiPleurotus sp.

Four mushroom strains ofPleurotus spp. were cultivated on sugar cane crop residues for 30 days at 26°C. Biochemical changes affected the substrate as a result of fungal growth, in terms of nitrogen, lignin, cellulose and hemicellulose contents. All strains showed a strong ligninolytic activity together with variable cellulolytic and xylanolytic action.Pleurotus sajor-caju attacked lignin and cellulose at the same rate, showing a degradation of 47% and 55%, respectively. A better balance was shown by theP. ostreatus-P. pulmonarius hybrid, which exhibited the poorest cellulolytic action (39%) and the highest ligninolytic activity (67%). The average composition of mushroom fruit bodies, in terms of nitrogen, carbohydrates, fats and amino acid profiles, was determined. Crude protein and total carbohydrate varied from 23% to 33% and 36% to 68% of dry matter, respectively. Fat ranged from 3.3% to 4.7% and amino acid content from 12.2% to 22.2%. Slight evidence for a nitrogen fixing capability was encountered in the substrate to fruit body balance.     

Microbiological and Biochemical Investigation of Succession in Lignin-Containing Compost Piles

The investigation of microbiological succession and changes in the enzymatic activity, temperature, pH, and phytotoxicity of lignin during its composting showed that the addition of a starter culture (a specially developed association of microorganisms) affects degradational succession in the compost pile. The process of composting can be monitored either microbiologically or biochemically, by measuring the activity of some enzymes. The compost is ready for use when the activity of oxidoreductases (particularly polyphenol oxidases) falls and the activity of invertase stabilizes at a certain level.     

Plant terpenes and lignin as natural cosubstrates in biodegradation of polyclorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs)

The objective of this minireview is to examine how cometabolic biodegradation of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) might be affected by plant terpenes and lignins as natural substrates abundant in nature. The topics covered, hence, are environmental significance of PCBs and PAHs, nature and distribution of plant terpenes and lignin, structural and metaoblic similarities of the natural compounds to PCBs and PAHs, and possible roles of the natural substrates in inducing the biodegradative pathways of PCBs and PAHs.     

Enzymatic and hydrolytic degradation of benzylaryl ethers related to hardwood lignins

A number of 4-hydroxybenzylphenyl ethers and their acetates were synthesized as models for hardwood lignin and used as substrates in acid hydrolysis and enzymatic oxidation reactions. Under hydrolytic conditions, the acetates underwent ether cleavage at a slower rate than the free phenols. Evidence for carbonium ion intermediates is presented. Cleavage of the ether substrates by peroxidase—peroxide oxidation was much faster than by acid hydrolysis for all substrates except the acetates which did not react. Subsequent oxidation of the component parts of the ether substrates was selective: the syringyl moieties were oxidized in preference to the guaiacyl moieties. Electron spin resonance studies of the oxidation reaction showed that removal of the phenolic hydrogen atom was the first step, followed by quinone—methide formation. A mechanism is proposed to account for the oxidative degradation of the lignin models.     

Identification of structural and chemical traits in Juglans regia associated with host plant preference of Batocera horsfieldi

1. Common walnut Juglans regia L. suffered devastating damage from the white‐striped longhorn beetle Batocera horsfieldi (Hope) in southwest China, which resulted in a dramatic decrease of local walnut production. However, the control of this wood‐boring pest with traditional methods is difficult as a result of its cryptic feeding habit.
2. We proposed that developing host‐plant resistance is a more effective way of controlling this insect with long‐term benefits. One way of improving host‐plant resistance is to identify plant traits related to host‐plant preference of targeted insects.
3. In the present study, we investigated the differences in feeding and oviposition preferences of B. horsfieldi on four J. regia cultivars in the field and tested whether such preferences are associated with structural and chemical traits in plant branches.
4. The results obtained showed that the host‐plant resistance of J. regia cultivars to B. horsfieldi was related to increased wood density, higher amounts of cellulose and lignin, and higher contents of tannins, total flavonoids and total phenolics, whereas the susceptible cultivars were characterized by thicker bark, higher contents of water, sugar and soluble protein.
5. The identified traits involved in host‐plant preference can subsequently contribute to the selection and breeding of resistant J. regia cultivars to B. horsfieldi.

     

On the occurrence of lignin or polyphenols in some mosses and liverworts

Six species of mosses (Musci) and two species of liverworts (Hepaticae) have been investigated for the presence of lignin by oxidative degradation. The results clearly demonstrate that these species are devoid of ligrin, but contain other types of phenolic cell wall material.     

Lignocellulose biodegradation: Fundamentals and applications

Lignocelluloses are the building blocks of allplants and are ubiquitous to most regions ofour planet. Their chemical properties make it asubstrate of enormous biotechnological value.The basic chemistry of cellulose,hemicellulose, and lignin has a profound effecton lignocellulose tertiary architecture. Theseintricate associations constitute physical andchemical barriers to lignocellulose utilizationand biodegradation in natural and man-madeenvironments. Overcoming these barriers is thekey to unlocking the commercial potential oflignocellulose. Understanding lignocellulosedegradation under natural conditions forms thebasis of any lignocellulose-based application.A variety of microorganisms and mechanisms areinvolved in the complete biodegradation oflignocellulose in natural environments rangingfrom soil and rumen ecosystems to the termitehindgut. The primary objective oflignocellulose pretreatment by the variousindustries is to access the potential of thecellulose and hemicellulose encrusted by ligninwithin the lignocellulose matrix. Currentworking technologies based on the principles ofsolid-state fermentation (SSF) are brieflyreviewed. The use of unsterile lignocellulosicsfor bioremediation purposes holds promise forcost-effective environmental clean-upendeavors. Novel lignocellulose-basedapplications have found functionality intextile, biological control, and medicalresearch fields and might be exploited there inthe near future. Ultimately, lignocellulosewill probably accompany man to his voyages intospace for interest in this field isintensifying. Therefore, proper management oflignocellulose biodegradation and utilizationcan serve to improve the quality of theenvironment, further man's understanding of theuniverse, and ultimately change local economiesand communities.