Lignin is regarded as the most plentiful aromatic polymer contains both non-phenolic and phenolic structures. It makes the integral part of secondary wall and plays a significant role in water conduction in vascular plants. Many fungi, bacteria and insects have ability to decrease this lignin by producing enzymes. Among these fungi are the major player in degradation of lignin. These fungi produce enzymes such as lignin peroxidases and laccases. The well-known fungi which degrades lignin are white, brown, soft-rot fungi, and deuteromycetes. Currently these fungi are utilized to reduce lignin to produce ecofriendly bioenergy. The primary aim of this paper is to describe the lignin degradation by biological pre-treatment using fungi (white-, brown-soft-rot fungi and molds), as well as biochemical application. Besides, Molecular methods and enzymes regulation engaged in fungal pre-treatment and some of the factors affecting pretreatment will also be briefly discussed.

There is a lack of knowledge regarding the variation physicochemical characteristics of humic substances (HS) extracted from various feedstock. For this purpose, humic acid (HA) and fulvic acid (FA) were extracted from soil, compost and clover straw to present several types of feedstock. The physicochemical properties of these humic substances were characterized for organic elements (C and N), total acidity and functional groups as well as IR spectra analysis.Data showed the feedstock recorded a significant effect on physicochemical properties of HS. Carbon and nitrogen concentrations varied widely among the extracted HS. The carbon and nitrogen concentrations in the extracted HA were more than the isolated fulvic acid. The C/N value of humic acid extracted from the soil was less than the other humic acids extracted from other sources. This trend was the same with FA indicating that the HA and FA extracted from the soil are more humified than other feedstock. Total acidity of FA was higher than HA with the superiority to those extracted from soils. The total content of active functional groups (COOH, total -OH, Phenolic -OH and Alcoholic-OH groups) was higher in FA as compared with HA, and the soil type was the most abundance source in most cases.Fourier transform infrared (FTIR) spectra confirm the presence of hydroxyl , aromatic and aliphatic fractions including quinone groups in humic and fulvic acids but in different values based on the feedstock.

The environmental and nutritional parameters were studied aiming to give a maximal exopolysaccharides (EPS) production by Bacillus subtilis. The basal medium (BM) was appeared to be the optimum medium among the seven tested media at 150 rpm. The highest production of EPS was obtained after 3 days incubation period, pH 7.0 and 25C. Sucrose was the best carbon source stimulating the maximum production of EPS followed by mannitol. The maximum production was achieved at concentration 4.5% of sucrose. The highest production of EPS was recorded by using yeast extract with a concentration of 0.22%.

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