Microbial proportion and heterotroph CO2 flux from drainage peatland under oil palm plantation

The difference in soil layer can affect heterotroph respiration that means CO2 fluxes from microbial decomposition in peatlands. Oil palm plants release root exudates transported to other places, i.e., shrub, by water movement, which can stimulate microbial activity. This study was conducted to learn the effects of differences of the soil layer and distance from the trunk in drainage peatland under oil palm plantation on total bacteria, fungi, cellulolytic bacteria, ligninolytic fungi, and heterotroph fluxes CO2, then compared to a shrub. Heterotroph respiration decreased with soil layer depth, where at the layer 0-20 cm released amount of CO2 as much 6.07 + 1.76, at 20-40 cm was 5.18 + 0.50, and at 40-60 cm 5.27 + 1.20 mg CO2 100 g-1 day-1, and tended higher than in shrub where a layer of 0-20 cm released 5.51 + 1.69, then decrease at 20-40 cm to 4.83 + 1.38, and at 40-60 cm 4.30 + 1.08 mg CO2 100 g-1 day-1. Total bacteria (107 CFU g-1) and fungi (105 CFU g-1) were higher than total cellulolytic bacteria (103 CFU g-1) and ligninolytic fungi (102 CFU g-1) in both under oil palm plantation and shrub. Organic acids affected the abundance of total bacteria and fungi but did not affect cellulolytic bacteria and ligninolytic fungi on both sites, as shown by a lower population and low cellulose and laccase enzymes. These findings showed that heterotroph CO2 flux tended higher in oil palm plantations and lignocellulolytic microbes are not the only source of heterotroph respiration.

Screening of ligninolytic fungi for bioremediation of dyes

Water pollution is a growing concern worldwide. One of the main causes of water pollution includes the textile industry which produces a large amount of wastewater every day. This wastewater is known to contain dyes that are recalcitrant and hard to treat. In order to solve this problem, bioremediation using ligninolytic fungi is commonly used for the ligninolytic enzymes which are able to break down the dyes. In this study, samples were collected from decaying woods and soils in the vicinity of UiTM Puncak Alam forests. A total of 20 fungal isolates were tested for ligninolytic enzyme production. Out of the 20 isolates, 13 were found to produce lignin peroxidase and manganese peroxidase, but only one produced laccase. The isolate that produced all three enzymes was used for DNA isolation and identified using amplification of the ITS region by PCR. The isolate was identified as Trichoderma asperellum, a soft rot fungal species which is renowned for its role in bioremediation as a biosorbent.

Degradation Products of Polychlorinated Biphenyls and Their In Vitro Transformation by Ligninolytic Fungi

Metabolites of polychlorinated biphenyls (PCBs)—hydroxylated PCBs (OH‑PCBs), chlorobenzyl alcohols (CB‑OHs), and chlorobenzaldehydes (CB‑CHOs)—were incubated in vitro with the extracellular liquid of Pleurotus ostreatus, which contains mainly laccase and low manganese-dependent peroxidase (MnP) activity. The enzymes were able to decrease the amount of most of the tested OH‑PCBs by > 80% within 1 h; the removal of more recalcitrant OH‑PCBs was greatly enhanced by the addition of the laccase mediator syringaldehyde. Conversely, glutathione substantially hindered the reaction, suggesting that it acted as a laccase inhibitor. Hydroxylated dibenzofuran and chlorobenzoic acid were identified as transformation products of OH‑PCBs. The extracellular enzymes also oxidized the CB‑OHs to the corresponding CB‑CHOs on the order of hours to days; however, the mediated and nonmediated setups exhibited only slight differences, and the participating enzymes could not be determined. When CB‑CHOs were used as the substrates, only partial transformation was observed. In an additional experiment, the extracellular liquid of Irpex lacteus, which contains predominantly MnP, was able to efficiently transform CB‑CHOs with the aid of glutathione; mono‑ and di-chloroacetophenones were detected as transformation products. These results demonstrate that extracellular enzymes of ligninolytic fungi can act on a wide range of PCB metabolites, emphasizing their potential for bioremediation.

DEGRADATION OF PERSISTENT POLLUTANTS BY LIGNINOLYTIC FUNGI

Screening of 20 strains of basidio- and ascomycetes for their degradative activity toward PAHs, nonionic surfactants, alkyl phenols, synthetic dyes, and oil permitted us to select the most active fungi which hold promise for further studies and for use in biotechnology.

Diversity and Geographic Distribution of Ligninolytic Fungi Associated With Castanopsis sieboldii Leaf Litter in Japan

The diversity and geographic pattern of ligninolytic fungi were investigated within the distribution range of an evergreen tree, Castanopsis sieboldii (Fagaceae), in Japan. Fungal isolates obtained from 18 sites in subtropical and temperate regions in Japan were classified into 50 operational taxonomic units in Ascomycota and Basidiomycota according to the base sequence of the rDNA internal transcribed spacer region. Ordination by nonmetric multidimensional scaling showed the separation of fungal compositions between the study sites which was significantly related to the latitude, longitude, and mean annual temperature (MAT) of the study sites. We applied variation partitioning to separate the magnitude of the climatic, spatial, and leaf property factors and found the roles of MAT and spatial factors in structuring fungal assemblages, suggesting the importance of both niche processes and such non-niche processes as priority effect and dispersal limitation. The bleached area on leaf litter was greater at sites with higher MAT and precipitation located at lower latitudes and at sites where some major ligninolytic fungi occurred at greater relative frequencies, indicating that not only the climatic conditions but also the biogeographic patterns of distribution of ligninolytic fungi influence the decomposition of lignin in leaf litter.

Biodegradation potential of indigenous litter dwelling ligninolytic fungi on agricultural wastes

Background The present study was focused to study the efficiency of two indigenous litter dwelling ligninolytic fungi (such as Mucor circinelloides GL1 and Fusarium verticillioides GL5) in degrading the agricultural wastes (areca husk, coffee husk and paddy straw) through solid-state fermentation. Results After fermentation process, the lignocellulosic residues left over were evaluated for their physico-chemical studies and degradation pattern of cell wall constituents along with the activity of enzymes. In each substrate, the initial pH was found to change from near-neutral to acidic pH after fungal decomposition. Significantly increased loss of total organic matter and organic carbon content was observed in each substrate decomposed by the fungal strains selected. The total nitrogen, crude protein, total phosphorus and total potassium contents of the fungal decomposed substrates were significantly increased with the progress of time. The study indicated that the degradation patterns of lignin and holocellulose were more effective from 20 to 120 days after fungal inoculation with respect to their loss between the different harvesting intervals. During decomposition process, both the strains produced the ligninolytic enzymes [laccase, manganese peroxidase (MnP) and lignin peroxidase (LiP)] and carboxymethyl cellulase (CMCase) on each substrate with their remarkably varied activities with respect to different harvesting times. Conclusions In concern with the present environmental problems, the present study suggested that these potential ligninolytic fungi can be utilized successfully for the management of agricultural wastes and reuse of their residues in the forest soil conservation system to eliminate the harmful effects of the crop residue burning.