Microbial diversity and digestive enzyme activities in the gut of earthworms found in sawmill industries in Abeokuta, Nigeria / Diversidad microbiana y actividad de enzimas digestivas en el intestino de las lombrices de tierra en los aserraderos de Abeokuta, Nigeria

The growing demand for wood has resulted in large volumes of wood wastes that are daily released to the soil from the activities of sawmills in South-Western Nigeria. In an attempt to setup a bioremediation model for sawdust, this study therefore aimed at evaluating microbial diversity, and the level of digestive enzymes in the gut of earthworms (Eudrilus eugeniae, Libyodrilus violaceous and Hyperiodrilus africanus) of sawmill origin. Four major sawmills located in Abeokuta (7o9’12” N - 3o19’35” E), namely Lafenwa, Sapon, Isale-Ake and Kotopo sawmills were used for this study. The arboretum of the Federal University of Agriculture, Abeokuta was used as control. Gut microbial analysis was carried out using the pour-plate method while digestive enzyme activities in the earthworm guts were done by the spectrophotometric method. Higher microbial counts (28.5±0.1x10³-97.0±0.1x10³cfu for bacteria and 7.0±0.1x10³-96.0±0.1x10³cfu for fungi) and microbial diversity were recorded in the gut of earthworms of the sawmill locations than those of the control site (17.5±0.1x10³cfu for bacteria and 4.5±0.1x10³cfu for fungi). Streptococcus mutans and Proteus spp.were common in the gut of E. eugeniae, and L. violaceous from the study sawmills, while Streptococcus mutans were also identified in H. africanus, but absent in the gut of E. eugeniae from the control site. Cellulase (48.67±0.02mg/g) and lipase (1.81±0.01mg/g) activities were significantly higher (p<0.05) in the gut of earthworms from the control site than those of the study sawmills. Furthermore, amylase (α and β) activity was highest in the gut of earthworms from the sawmills. Variations observed in the gut microbial and digestive enzyme activities of earthworms from the study sawmills as compared to the control site suggests that earthworms, especially E. eugeniae, could be a better organism for use as bioremediator of wood wastes. Rev. Biol. Trop. 62 (3): 1241-1249. Epub 2014 September 01.

La creciente demanda de madera ha resultado en grandes volúmenes de residuos de madera que se lanzan diariamente a la tierra, procedentes de las actividades de los aserraderos en el suroeste de Nigeria. Se realizó este estudio en un intento de configurar un modelo de biorremediación de aserrín, con el objetivo de evaluar la diversidad microbiana y el nivel de las enzimas digestivas en el intestino de las lombrices de tierra (Eudrilus eugeniae, Libyodrilus violáceo y Hyperiodrilus africanus) de origen aserradero. Para este estudio se utilizaron cuatro grandes aserraderos ubicados en Abeokuta (7°9’12 ‘’ N - 3°19’35 ‘’ E), a saber: Lafenwa, Sapon, Isale-Ake y Aserraderos Kotopo. El arboreto de la Universidad Federal de Agricultura, Abeokuta se utilizó como control. El análisis microbiano se llevó a cabo utilizando el método de vertido de placa, mientras que las actividades de enzimas digestivas en los intestinos de las lombrices se realizaron por el método espectrofotométrico. Los recuentos microbianos más altos fueron 28.5±97.0±0.1x10³-0.1x10³cfu para las bacterias y 7.0±0.1x10³-96.0±0.1x10³cfu para los hongos y la diversidad microbiana registrada en el intestino de las lombrices de tierra de los lugares de aserraderos y las del sitio de control fueron: 17.5±0.1x10³cfu para bacterias y 4.5±0.1x10³cfu para hongos. Streptococcus mutans y Proteus spp. eran comunes en el intestino de E. eugeniae, y L. violaceous de los aserraderos de estudio, mientras que también se identificaron Streptococcus mutans en H. africanus, que estuvieron ausentes en el intestino de E. eugeniae en el sitio de control. Actividades de celulasa (48.67±0.02mg/g) y lipasa (1.81±0.01mg/g) fueron significativamente mayores (p<0.05) en el intestino de las lombrices de tierra en el sitio de control que las de los aserraderos de estudio. Por otra parte, la actividad de la amilasa (α y β) fue mayor en el intestino de las lombrices de tierra de los aserraderos. Las variaciones observadas en la microbiota intestinal y la actividad de las enzimas digestivas de las lombrices de tierra de los aserraderos de estudio, en comparación con el sitio de control, sugieren que las lombrices de tierra, especialmente E. eugeniae, podrían ser un mejor organismo para su uso como biorremediador de residuos de madera.

Phosphate solubilizing ability of Emericella nidulans strain V1 isolated from vermicompost.

Phosphorus is one of the key factors that regulate soil fertility. Its deficiencies in soil are largely replenished by chemical fertilizers. The present study was aimed to isolate efficient phosphate solubilizing fungal strains from Eisenia fetida vermicompost. Out of total 30 fungal strains the most efficient phosphate solubilizing one was Emericella (Aspergillus) nidulans V1 (MTCC 11044), identified by custom sequencing of β-tubulin gene and BLAST analysis. This strain solubilized 13 to 36% phosphate from four different rock phosphates. After three days of incubation of isolated culture with black Mussorie phosphate rock, the highest percentage of phosphate solubilization was 35.5±1.01 with a pH drop of 4.2±0.09. Kinetics of solubilization and acid production showed a linear relationship until day five of incubation. Interestingly, from zero to tenth day of incubation, solubility of soil phosphate increased gradually from 4.31±1.57 to 13.65±1.82 (mg kg-1) recording a maximum of 21.23±0.54 on day 45 in respect of the V1 isolate. Further, enhanced phosphorus uptake by Phaseolus plants with significant pod yield due to soil inoculation of Emericella nidulans V1 (MTCC 11044), demonstrated its prospect as an effective biofertilizer for plant growth.

Diversity of microflora in the gut and casts of tropical composting earthworms reared on different substrates.

The diversity of fungi, bacteria, yeast, actinomycetes and protozoa were analysed in the gut and casts of Eudrilus eugeniae, Lampito mauritii, Eisenia fetida and Perionyx excavatus, both qualitatively and quantitatively as influenced by different feed substrates like clay loam soil, cowdung and pressmud. While actinomycetes (Streptomyces albus, S. somaliensis, Nocardia asteroides, N. caviae and Saccharomonosporia) were not digested by any of these species of worms, protozoa (Amoeba proteus, A. terricola, Paramecium trichium, Euglena viridis, E. orientalis, Vorticella picta and Trichomonas hominis) and yeast (Candida tropicalis, C. krusei C. albicans and Cryptococcus neoformans) were totally digested. Certain species of fungi (Saksenae vasiformis, Mucor plumbeus, Cladosporium carrionii, C. herbacium, Alternaria sp., Cunninghamella echinulata, Mycetia sterila, Syncephalostrum racemosum, Curvalaria lunata, C. geniculata and Geotrichum candidum) and bacteria (Pseudomonas aeruginosa, Bacterium antitratum, Mima polymorpha, Enterobacter aerogenes, E. cloacae, Proteus vulgaris, P. mirabilis, P. rettgeri, Escherichia coli, Staphylococus citreus, Bacillus subtilis, B. cereus, Enterococci and Micrococci) were completely digested. Certain other species were not digested fungi like Aspergillus fumigatus, A. flavus, A. ochraceous, Trichoderma koningii (except by Eeugeniae), Fusarium moniliforme (except by E. eugeniae) and Rhizopus sp., and bacteria like Klebsiella pneumoniae and Morganella morganii) and these were multiplied during the transit of the organic residues through the gut of worms. The microbial proliferation was more in the casts, due to the environment prevailing--rich in nutrient supply and large surface area available for growth and reproduction of the microbes that lead to enhanced microbial activity and humic acid contents in the casts.

Distribution of bacteria and fungi in the earthworm Libyodrillus violaceous (Annelida: Oligochaeta), a native earthworm from Nigeria

Earthworms are soil invertebrates that play a key role in recycling organic matter in soils.In Nigeria, earthworms include Libyodrillus violaceous. Aerobic and anaerobic bacterial counts, as well as fungal counts of viable microorganisms in soils and gut sections, were made on twenty L. violaceous collected from different sites on the campus of the University of Agriculture, Abeokuta, Nigeria. The samples were collected between April and November, 2002. Numbers of microorganisms were higher in castings and gut sections than in uningested soil samples. The guts and their contents also had higher moisture and total nitrogen contents than the uningested soils. Bacteria and fungi isolated from the samples were identified by standard microbiological procedures on the bases of their morphological and biochemical characteristics. Isolated bacteria were identified as Staphylococcus, Bacillus spp., Pseudomonas aeruginosa, Streptococcus mutans, Clostridium, Spirocheata spp., Azotobacter spp., Micrococcus lylae, Acinetobacter spp., Halobacterium for bacteria. Yeast isolates were identified as Candida spp., Zygosaccharomyces spp., Pichia spp., and Saccharomyces spp while molds were identified as, Aspergillus spp., Pytium spp., Penicillium spp., Fusarium spp and Rhizopus spp. Of the five locations examined, the refuse dump area had the highest numbers of both aerobic and anaerobic organisms, followed by the arboretum while the cultivated land area recorded the lowest counts. The higher numbers of microorganisms observed in the gut sections and casts of the earthworms examined in this work reinforce the general concept that the gut and casts of earthworms show higher microbial diversity and activity than the surrounding soil.