Nanoscale Res Lett (2010) 5:1408–1417 These bacteria seem to actively contribute to the rapid formation of huge siliceous deposits [10]. In general, the biosiliﬁcation products are commonly composed of amorphous silica (opal-A, opal-CT and opal- C), and other crystal arrays such as cristobalite, trydimite and quartz. In particular, amorphous silica is a dominant component in marine surface sediment most of which is considered to be generated by the activity of living organism [3, 11]. Many scientists not only investigate the process underlying their formation, but also aim to mimic these processes in order to obtain better control over the structure and morphology of chemically produced silica [12–14]. The natural silica production receives increasing attention, since it holds the key to the formation of silica morphologies with a dedicated organization of hierarchi- cally structure elements and the ability to synthesize such silica under ambient conditions [15]. There exist many studies in silica bio-mineralization of simple aquatic life forms, including unicellular organisms like diatoms, radiolaria and sinurophytes as multicellular sponges [16–19]. In the soil, silica plays a major role in higher plants [20]. Many plants sequester silica in biogenic phytoliths and soils can accumulate signiﬁcant quantities of biogenic opal- A [21]. The silica absorbed for terrestrial plants is around a fraction of 1% of the dry matter to several percent, and in some plants to 10% or even higher [22]. It is observed that in some grammineae as rice (Oryza sativa), silica constitutes 20–22% of its total production in the rice husk form [23]. Sugarcane bagasse contains around 5.08 to 7.08% of silica in dry matter basis [24], and coffee husk contains around 1 to 3% of silica in dry matter basis [25]. It is important to mention that the mechanical strength of plants resides greatly on the cell wall, enabling them to achieve and maintain erect habit conductive to light inter- ception. There exist a relation in plants stress and the increased rigidity of cell walls of plants grown with ample available silica [26, 27]. When plants die, the silica is rein- corporated into the soil where microorganisms play an important role in the degradation of organic matter and in the release of minerals nutrients [28, 29], other important source that raises mineralization rate is earthworms producing biohumus. Humus contains principally carbon, oxygen, hydrogen and minor proportion of other minerals. These elements vary within the humic material in order to deﬁne chemical characteristics of the original basis. There exists a symbiotic interaction between earthworms and microor- ganisms that breakdown and fragment the organic matter progressively, ﬁnally incorporating it into water-stable aggregates. The mineral nutrients in earthworm casts and lining earthworm burrows are in a form readily available to plants. There is evidence that interactions between earth- worms and microorganisms not only provide these available nutrients, but stimulate plant growth indirectly in others 1409 ways [30]. The digestive system of earthworms consists of a pharynx, esophagus and gizzard (zone reception) followed by an anterior intestine that secrets enzymes and a posterior intestine that absorb nutrients. During progress through this digestive system, there is a dramatic increase in numbers of microorganism of up to 1,000 times. The digestive systems of earthworms from different species, genera and families differ in detail, but their gusts have a common basic structure. In different species earthworms Eisenia foetida is peculiar for its degradation rate [28]. Most studies of digestive enzymes in earthworms have been limited to the lumbricids. Protease, lipase, amylase, lichenase, cellulose and chitinase activities also have been described [31]. A wide range of microorganisms, including bacteria, algae, protozoa, acti- nomycetes, fungi and even nematodes, are found commonly throughout the length of the earthworms gut. The species of microbes in the gut are usually very similar to those in the surrounding soil or organic matter upon which the earth- worms feed [32–34]. Eisenia foetida is considered a machine to produce humus in conditions environmental control and the microorganism can live in it in anoxic effect raising productivity in the material expel. The biological mechanism to earthworms transforms organic matter and even so carries out biosiliﬁcation even is uncertain. Understanding the mechanism of silica nanofabrication in other organisms is supported by a precursor namely biosilica monosilicic acid Si(OH)4 [35, 36]. Proteins have been isolated from diatoms, sponges and grasses that are proposed to be responsible for biosiliﬁcation and have been sequenced and some of the key amino acids identiﬁed. Other authors have studied the role of homopolymers of various amino acids that are key constit- uents of the proteins lysine, histidine, arginine, cysteine, proline and serine in the process biosiliﬁcation [37]. This biopolymer acts as gelating agents of silica oligomers in silicic acid and as ﬂocculation agents in silica sols [38, 39]. Other researches have been focused toward the development of efﬁcient and innovative fabrication methods to obtain inorganic materials using microorganisms from potential cheap agro-industrial waste materials and could lead to an energy-conserving and economically viable green approach toward the large-scale synthesis of oxide nanomaterials [9]. Thus, we develop a novel process for synthesis of diverse nanometric materials with speciﬁc crystal arrays as precur- sors to agro-industrial wastes employing annelids, an approach not used before, that permit to rise natural sources dedicated to production particles’ mean biosiliﬁcation. Experimental Three sources derived from agro-industrial activity were used: rice husk, coffee husk and sugarcane bagasse. These by-products were added to vermicompost separately. The 123