Coffee pulp waste composition consist of cellulose, hemicellulose, lignin, pectin and caffeine, tannin, and polyphenol as inhibitor substance. The high cellulose compound in coffee pulp can be used for alternative raw materials in the manufacture of biogas. This study aims to define the composition of the mixture of microorganisms of Pseudomonas putida, Trichoderma harzianum, and Aspergillus niger that are best to use in coffee pulp pretreatment to degrade inhibitor substance. The best result of pretreatment will be applied to biogas production. The first step is to do a pretreatment of the coffee pulp with variable Pseudomonas putida : Trichoderma harzianum : Aspergillus niger with a ratio of 1:1:1, 1:2:1, 1:1:2, 1:2:2, 2:1:1, 2:1:2, 2:1:1 (v:v:v), then variables that are most excellent in degrading inhibitor substance are selected. The second step, is doing anaerobic fermentation for 20 days at mesophilic temperature (30-40°C) on a reactor working volume of 4.5 L. In the making of biogas, a varied starter as much as 10% of the total are put into the reactor in the form of a mixture of cow dung : rumen fluid with a ratio of 1:0, 0:1, 1:1, 1:2, 2:1 (w/v). The parameters measured include the decreasing of the inhibitor substance, Chemical Oxygen Demand (COD), biogas (CH4 and CO2) and calorific value of combustion (Heating value). This study results a composition of ingredients within the pretreatment process which includes a mixture of microorganisms with a ratio of Pseudomonas putida : Trichoderma harzianum : Aspergillus niger is 1:2:1 (v:v:v). For biogas, a mixture of cow dung and rumen fluid can produce higher methane gas is the ratio of cow dung : rumen fluid is 1:2 (w/v) with the concentration of methane (CH4) formed at 1.825%. At the concentration of methane is 1.825%, the heating value obtained is 76.032 kcal/kg with volume biogas 0.0032 m3/ kg converted of COD.

Abstract. Iswanto T, Shovitri M, Altway A, Widjaja T, Kusumawati DI, Lisdiyanti P. 2019. Isolation and identification of caffeine-degrading bacteria from soil, coffee pulp waste and excreted coffee bean in Luwak feces. Biodiversitas 20: 1580-1587. The present study deals with the isolation and identification of caffeine-degrading bacteria obtained from the caffeine contaminated environment or caffeinated wastes. These bacteria are useful for various biotechnological applications especially in increasing the potential utilization of caffeinated wastes and producing the high-value chemicals. The suspected caffeine-degrading bacteria have been isolated from the soil of coffee plantation area, coffee pulp waste, and the excreted coffee bean in fresh feces of Luwak (Paradoxurus hermaphroditus or Asian Palm Civet) by growing them on the caffeinated agar medium (CAM) containing basal salt medium (M9) and caffeine as a sole source of carbon and nitrogen. CAM-supplemented with 1.5 to 10 g L-1 of caffeine has been used for screening of the potential bacteria which able to grow in high caffeine concentration. Molecular identification based on 16S rRNA gene sequence was performed to identify the selected bacteria. The result revealed that there were 11 and 3 strains of 12 selected bacteria which could grow on the CAM-supplemented with caffeine up to 7 and 10 g L-1, respectively. Based on 16S rRNA gene sequence and phylogenetic analysis, those bacteria were from 5 Gram-negative species, namely Pseudomonas japonica (4/12), Methylobacterium populi (5/12), Raoultella ornithinolytica (1/12), Klebsiella quasipneumoniae (1/12), and Stenotrophomonas chelatiphaga (1/12). Further investigations to determine their metabolic pathway, enzyme, and growth kinetics in the caffeinated medium may provide insights into its possible utilization for scientific or other applications.

The effect of alkaline hydrogen peroxide (AHP) treatment on reducing lignin content in coffee pulp waste (CPW) was investigated to increase the digestibility and accessibility of cellulose during production of valuable products by enzymatic and biological process. Hydrogen peroxide (H2O2) at various concentrations (2.5, 5, and 7.5% (w/w of substrate)) was mixed into 10% (w/v) of CPW-NaOH solution at 35 °C for 24 h with pH 11.5. The concentration of lignocellulosic content was investigated. The characteristic of crystallinity index, functional groups, and surface morphology of CPW at before and after the treatment have been observed using XRD, FTIR, and SEM analysis, respectively. The results showed that the highest lignin removal was achieved at the addition of 7.5% H2O2 which decreased from 16.85% to 8.5%. The concentration of cellulose and hemicellulose in CPW increased from 53% to 64% and 11% to 24%, respectively. The crystallinity index of AHP-treated CPW has increased from 30.83% to 42.08%. A surface morphological destruction on the CPW was getting worse as along with the increase of H2O2 concentration. This would be useful to increase the porosity of biomass to give cellulose accessibility by enzyme for further processes.

Biological methods using bacteria and fungi are regarded as more economically viable and environmentally friendly alternatives for improving lignocellulosic degradation. Coffee pulp waste (CPW) as a lignocellulosic biomass is abundant and has potential as a reducing sugar feedstock. However, it contains lignin as a matrix polymer, which associated with pectin and cover the cellulosic microfibrils and make it difficult to be digested during the bioprocess. In this study, the performance of biological pretreatment in reducing lignin and pectin using a coculture of Bacillus subtilis (BS), Aspergillus niger (AN), or Trichoderma reesei (TR) has been investigated. The pretreatment of the CPW was made using various microbial ratios in an aerobic stirred-bioreactor and incubated at 30 o C, pH 5 for 7 days. Removal of lignin and pectin was analyzed during the pretreatment process. PEG 4000 as a surfactant was used and its effect on the yield of reducing sugar production from pretreated CPW using a A. niger and T. viride (TV) co-culture with a surfactant to substrate ratio of 1:1 (w/w) was investigated. A culture without surfactant was used as a control. The results reveal that the best lignin and pectin removal was 99.9%, when using a co-culture of AN and TR with a ratio of 1:1 (v/v) and of BS and TR with a ratio of 2:1 (v/v). The cellulose content of CPW in these co-cultures was 86.99% (w/w) and 81.61% (w/w), respectively, and the reducing sugar concentration obtained was 12.5 g/L and 9.74 g/L respectively. In further hydrolysis of pretreated CPW using a AN:TV (2:1) coculture with the addition of surfactant, the yield of reducing sugar obtained was higher than that of the control, at 20.69%. Use of PEG 4000 as a surfactant had a positive effect on enhancing the yield of reducing sugar from coffee pulp waste.

No abstract