Isolation of cellulolytic bacteria, including actinomycetes, from coffee exocarps in coffee-producing areas in Vietnam

Background Microorganisms have been used to decomposecellulolytic waste in agriculture for the past manyyears. However, much of the cellulosic waste includingcoffee exocarps which are wastes from raw coffee processin Vietnam is often disposed of by biomass burning anddischarged into the environment in developing countries,thus causing considerable environmental pollution.Besides, these organic wastes decompose slowly when theyare used to produce compost in ordinary conditions.Therefore, using microorganisms to manufacture naturalcompost from coffee exocarps is considered a useful andenvironmentally sound alternative.Results In the course of screening for cellulose-degradingbacteria and actinomycetes, 38 bacterial strains and 18actinomycetes strains were isolated from 15 coffee exocarpsamples in coffee-producing areas in Vietnam. The isolatesgrew with cellulose as the sole sources of carbon andenergy. The results of cellulolytic activity determinationswere that 13 bacteria ([34 %) and 10 actinomycetes([56 %) showed enzymatic degradation of cellulose. Theisolated strains were identified as belonging to members ofthe Genus Streptomyces, Actinomycetes, Clostridium andBacillus. Cellulose-degrading ability of the isolatedmicroorganism strains was mostly 96 % with filter paper;however, for coffee exocarps, it was considerably lower,only about 37 % of the cellulose was digested after 30 daysof incubation to coffee exocarps. A medium containing ricehusk powder and lactose with pH 7.0 positively affectedthe cellulolytic activity of A1 and A9 strains. Cellulolyticactivity of B4 and B7 strains was also most appropriatewhen the medium contained peptone, CMC, and with a pH7.0. Optimal temperature for actinomycetes and bacteriaisolate strains was at 25–35 C.Conclusion We concluded that the cellulolytic bacteriaand actinomycete could be isolated from coffee exocarpswhich are normally discharged into the environment incoffee-producing areas. These microorganisms could beused to decompose cellulosic wastes, making compostfrom coffee exocarps, which could be applied in agriculturein Vietnam and other developing countries.