Outlining Metabolic Versatility of a Commercial Waste Composting Consortium in Fish Waste Management

Effective and sustainable management of fish wasteproduced in markets and processing industries, isa major challenge faced by the coastal communities.Composting is an environment friendly method forfish waste disposal, and for the production oforganic fertilizers. However, quality of compostdepends on the use of proficient microbial consortiato mediate the bioconversion processes. Accordingly,as a first step in developing a competent fishwaste composting strategy, suitability of a commercialorganic waste composting consortium wasassessed. For this, various selective media were usedfor outlining the metabolic activities required forwaste degradation such as production of hydrolyticenzymes viz., chitinase, lipase and protease (both instandard media and fish waste component embeddedmedia), ammonia oxidization, organic andinorganic phosphate solubilisation, nitrite oxidizationand sulphur oxidization. There were potentialproducers for all organic waste degrading enzymeswith highest enzymatic index (EI) as 1.8, 2.9 and 1.5for protease, lipase and chitinase respectively.Among these, 10 microbial consortia were able todegrade fish waste components with the highest EIas 1, 2.4 and 0.2 for protein, chitin and oilrespectively; indicating that efficacy of fish oildegraders in the evaluated consortia was very less.Four isolates were found efficient for denitrification.Highest organic and inorganic phosphatesolubilisation efficiency was 1.9 and 7 respectively.Despite the presence of some AOB (ammoniaoxidizing bacteria), NOB (nitrite oxidizing bacteria)and SOB (sulphur oxidizing bacteria), their efficacy was less. Potential isolates were characterized as Lysinibacillus xylanilyticus, Halotalea sp, Bacillus oryzaecorticis, Cronobacter condiment and Bacillusmegaterium. As fish waste is rich in nitrogen andsulphur, inclusion of efficient AOB, NOB and SOBcan improve the quality of final compost. Similarly,exclusion of denitrifiers can avoid the loss ofnitrogen during composting. Consequently, whilethere were efficient organic matter degradingenzyme producers including fish protein and chitin,absence of efficient AOB, NOB, fish oil degradersand presence of denitrifiers recommends an improvisationof the evaluated consortium before applicationin fish waste composting.