Dextran, which is manufactured by the fermentation of sucrose by Leuconostoc mesenteroides or related species of bacteria, is also being developed as a fibrous non-woven for speciality end-uses such as wound dressings.

Bio-auxiliary in dyes and pigments

Manufacturing of natural dyes from different wood berk, leaves, fruits, tea extraction becomes a novel approach towards the use of biomaterial in dyeing. Textile auxiliaries such as dyes could be produced by fermentation or from plants in the future (note: before the invention of synthetic dyes in the nineteenth century many of the colours used to dye textiles came from plants. e.g. woad, indigo and madder).

Many micro-organisms produce pigments during their growth which are substantive as indicated by the permanent staining that is often associated with mildew growth on textiles and plastics. It is not unusual for some species to produce up to 30% of their dry weight as pigment.

Several of these microbial pigments have been shown to be benzoquinone, naphthoquinone, anthraquinone, perinaphthenone and benzofluoranthenequinone derivatives, resembling in some instances the important group of vat dyes.

Micro-organisms would therefore seem to offer great potential for the direct production of novel textile dyes or dye intermediates by controlled fermentation techniques replacing chemical synthesis which has inherent waste disposal problems (e.g. toxic heavy metal compounds).

The production and evaluation of microbial pigments as textile colorants is currently being investigated at BTTG.

Waste Management

Biotechnology can be used in new production processes that are themselves less polluting than the traditional processes and microbes or their enzymes are already being used to degrade toxic wastes. Waste treatment is probably the biggest industrial application of biotechnology. Specific problems pertaining to the textile industry include colour removal from dyehouse effluent, toxic heavy metal compounds and pentachlorophenol used overseas as a rot-proofing treatment of cotton fabrics but washed out during subsequent processing.

Currently much research is being carried out to resolve these problems and biotechnology would appear to offer the most effective solutions. Biological treatment of effluent is termed as secondary treatment. The objective of treatment is to achieve bio-flocculation.

The micro-organisms convert the colloidal and dissolved carbonaceous matter into various gases and cell tissues. The cell tissues have a specific gravity slightly higher than that of water and hence can be removed by gravity settling. Bacterium 'shewanella sp' can couple growth to the biodegradation of reactive azo dyes.

It is thought that colour removal process involves transfer of electrons from the cell to the dye molecule, via a dye reductase, this results in reduction of the chromophore i.e., the azo bonds, to produce a significantly less coloured solution that contains amines.

Lignin peroxidase, manganese peroxidase and Laccase are produced by white rot fungi and are believed to involve in degradation of lignin and wide variety of recalcitrant xenobiotic compounds. Many rot fungi including pycnoporuscinnacarit, pleurotusostreatus, etc. have been found to be efficient in degrading dyes.

White rot fungi may oxidatively degrade dyes by means similar to lignin degradation typically associated with enzymes.

End use of bio-auxiliaries in textiles

Textile processing with bio-auxiliaries aims to provide the textile technologist with an understanding of enzymes and their use with textile materials and in process engineering. It covers all the relevant aspects of textile processing with bio-auxiliaries, from the chemical constitution and properties of textile materials as potential substrates for bio-auxiliaries, to the processing of these materials; from basic biochemistry and enzymology to the industrial application of bio-auxiliaries.