Shrimps have been a popular raw material for the burgeoning marine and food industry contributing to increasing marine waste. Shrimp waste, which is rich in organic compounds is an abundant source of chitin, a natural polymer of N-acetyl-D-glucosamine (GluNac), a reducing sugar. For this respect, chitinase-producing fungi have been extensively studied as biocontrol agents. Locally isolated Trichoderma virens UKM1 was used in this study. The effect of agitation and aeration rates using colloidal chitin as control substrate in a 2-l stirred tank reactor gave the best agitation and aeration rates at 200 rpm and 0.33 vvm with 4.1 U/l per hour and 5.97 U/l per hour of maximum volumetric chitinase activity obtained, respectively. Microscopic observations showed shear sensitivity at higher agitation rate of the above system. The oxygen uptake rate during the highest chitinase productivity obtained using sun-dried ground shrimp waste of 1.74 mg of dissolved oxygen per gram of fungal biomass per hour at the kappaL a of 8.34 per hour.
The oil palm sector is one of the major plantation industries in Malaysia. Palm kernel cake is a byproduct of extracted palm kernel oil. Mostly palm kernel cake is wasted or is mixed with other nutrients and used as animal feed, especially for ruminant animals. Recently, palm kernel cake has been identified as an important ingredient for the formulation of animal feed, and it is also exported especially to Europe, South Korea, and Japan. It can barely be consumed by nonruminant (monogastric) animals owing to the high percentages of hemicellulose and cellulose contents. Palm kernel cake must undergo suitable pretreatment in order to decrease the percentage of hemicellulose and cellulose. One of the methods employed in this study is fermentation with microorganisms, particularly fungi, to partially degrade the hemicellulose and cellulose content. This work focused on the production of enzymes by Aspergillus niger and profiling using palm kernel cake as carbon source.
Twenty seven filamentous fungal strains representing five genera; Aspergillus, Penicillium, Trichoderma, Myriodontium and Pleurotus were isolated from four sources; domestic wastewater sludge cake (SC) from IWK (Indah Water Konsortium) wastewater treatment plant, palm oil mill effluent compost from Sri Ulu palm Oil Processing Mill, compost of plant debris, and fungal fruiting bodies from a rotten wood stump. Thirty-three strains/isolates were tested for their ability to convert domestic wastewater sludge into compost by assessing biomass production and growth rate on sludge enriched media. The strains/isolates Aspergillus niger, SS-T2008, WW-P1003 and RW-P1 512 produced the highest dry biomass at higher sludge supplemented culture media from their respective group (Aspergillus, Trichoderma, Penicillium and Basidiomycetes, respectively). This implied these strains are better adapted for growth at higher sludge rich substances, and subsequently may be efficient in bioconversion/biodegradation of sludge. The fungi isolated from ecological closely related sources were more amendable to adaptation in a sludge rich culture media.
Ten filamentous fungi adapted to domestic wastewater sludge (DWS) were further studied to evaluate their potential in terms of adaptation to higher sludge supplemented growing media and phytopathogenicity (induction of diseases to plants) to three germinating crop (Corn: Zea mays, Mung bean: Phaseolus aureus and Mustard: Brassica napus) seeds. The performances of the fungi in seed germination were evaluated based on percent germination index (GI) and infected/spotted seeds on direct fungal biomass (FBM) and fungal metabolite (FM). Significantly the highest biomass production was achieved with RW-P1 512 and Penicillium corylophilum (WW-P1003) at the highest (25%) sludge supplemented growing media that implied its excellent potentiality of adaptation and multiplication to domestic wastewater sludge. Significantly encouraging results of percent GI and spotted/infected seedlings were observed in FM than FBM by all fungi except the strain Aspergillus niger. A. niger gave the poorest percent of GI (24.30, 26.98 and 00.00%) and the highest percent of infected/spotted seeds (70, 100, and 100%) using FBM for corn, mung bean and mustard, respectively. On the other hand, comparatively the highest percent of GI (107.99, 106.25 and 117.67%) and the lowest percent of spotted/infected seedlings (3.3, 3.3 and 3.3%) were achieved with the isolate RW-P1 512 using FM. In FBM, the superior results of percent GI (86.61, 95.92 and 83.87%) and spotted/infected seedlings (3.3, 63.3 and 43.3%) were obtained by A. versicolor. Several crop seeds were responded differently for different fungal treatments. Hundred percent infected/spotted seeds in FM were recorded only for mustard with Trichoderma family that implied its strong sensitiveness to its metabolites.
Bioconversion of higher strength of domestic wastewater biosolids (sludge) (4% w/w of TSS) by mixed fungal culture of Aspergillus niger and Penicillium corylophilum was studied in a laboratory. The effect of potential mixed fungi on domestic wastewater sludge accelerated the liquid state bioconversion (LSB) process. The highest production of dry sludge cake (biosolids) was enriched with fungal biomass to about 85.66 g/kg containing 25.23 g/kg of protein after 8 days of treatment. The results presented in this study revealed that the reduction of chemical oxygen demand (COD), total suspended solid (TSS), and specific resistance to filtration (SRF) of treated sludge were highly influenced by the fungal culture as compared to control (uninnoculated). The maximum removal rates in treated sludge (biosolids) supernatant recorded were 92% of COD and 98.8% of TSS. Lower SRF (1.08 x 10(12) m/kg) was perceived in microbially treated sludge after 6 days of fermentation. The observed parameters were highly influenced after 8 days of treatment. The influence of pH was also studied and presented in the paper.
The bioconversion of domestic wastewater sludge by immobilized mixed culture of filamentous fungi was investigated in a laboratory. The potential mixed culture of Penicillium corylophilum WWZA1003 and Aspergillus niger SCahmA103 was isolated from its local habitats (wastewater and sludge cake) and optimized on the basis of biodegradability and dewaterability of treated sludge. The observed results in this study showed that the sludge treatment was highly influenced by the effect of immobilized mixed fungi using liquid state bioconversion (LSB) process. The maximum production of dry filter cake (DFC) was enriched with fungal biomass to about 20.05 g/kg containing 23.47 g/kg of soluble protein after 4 days of fungal treatment. The reduction of COD, TSS, turbidity (optical density against distilled water, 660 nm), reducing sugar and protein in supernatant and filtration rate of treated sludge were influenced by the fungal mixed culture as compared to control (uninnoculated). After these processes, 99.4% of TSS, 98.05% of turbidity, 76.2% of soluble protein, 98% of reducing sugar and 92.4% of COD in supernatant of treated sludge were removed. Filtration time was decreased tremendously by the microbial treatment after 2 days of incubation. The effect of fungal strain on pH was also studied and presented. Effective bioconversion was observed after 4 days of fungal treatment.
A study was carried out to isolate and identify filamentous fungi for the treatment of domestic wastewater sludge by enhancing biodegradability, settleability and dewaterability of treated sludge using liquid state bioconversion process. A total of 70 strains of filamentous fungi were isolated from three different sources (wastewater, sewage sludge and leachate) of IWK's (Indah Water Konsortium) sewage treatment plant, Malaysia. The isolated strains were purified by conventional techniques and identified by microscopic examination. The strains isolated belonged to the genera of Penicillium, Aspergillus, Trichoderma, Spicaria and Hyaloflorae The distribution of observed isolated fungi were 41% in sewage sludge followed by 39% in wastewater and 20% in leachate. The predominant fungus was Penicillium (39 strains). The second and third most common isolates were Aspergillus (14 strains) and Trichoderma (12 strains). The other isolates were Spicaria (3 strains) and Hyaloflorae (2 strains). Three strains (WWZP1003, LZP3001, LZP3005) of Penicillium (P. corylophilum, P. waksmanii, and P. citrinum respectively), 2 strains (WWZA1006 and SS2017) of Aspergillus (A. terrues and A. flavus respectively) and one strain (SSZT2008) of Trichoderma (T. harzianum) were tentatively identified up to species level and finally verified by CABI Bioscience Identification Services, UK.
The importance and development of industrial biotechnology processing has led to the utilisation of microbial enzymes in various applications. One of the important enzymes is amylase, which hydrolyses starch to glucose. In Malaysia, the use of sago starch has been increasing, and it is presently being used for the production of glucose. Sago starch represents an alternative cheap carbon source for fermentation processes that is attractive out of both economic and geographical considerations. Production of fermentable sugars from the hydrolysis of starches is normally carried out by an enzymatic processes that involves two reaction steps, liquefaction and saccharification, each of which has different temperature and pH optima with respect to the maximum reaction rate. This method of starch hydrolysis requires the use of an expensive temperature control system and a complex mixing device. Our laboratory has investigated the possibility of using amylolytic enzyme-producing microorganisms in the continuous single-step biological hydrolysis of sago flour for the production of a generic fermentation medium. The ability of a novel DNA-recombinated yeast, Saccharomyces cerevisiae strain YKU 107 (expressing alpha-amylase production) to hydrolyse gelatinised sago starch production has been studied with the aim of further utilizing sago starch to obtain value-added products.