Potential of Earthworm (Perionyx Excavatus) in food treatment in Ho Chi Minh City

In Ho Chi Minh City, Vietnam, there are about 9 thousand tons of domestic waste every day and 73% of them are treated by using landfill sites [2]. With the population growth rate in recent years, the generated waste volume will then increase in the future and is estimated to reach a total of around 13 thousand tons that could cost Ho Chi Minh City about 260 thousand dollars in treating this waste in 2025 [3]. Although this treatment method is not without advantages, the downsides will be far more significant. Moreover, in recent years, the cultivation of Perionyx Excavatus, a species that had been reported to have the ability to treat organic waste in some foreign articles, has become increasingly popular in Vietnam. So, this research was aimed to evaluate the potentiality of Earthworm (Perionyx Excavatus) for food waste management of households in Lab-scale in Ho Chi Minh City, Vietnam. According to this study, the average outdoor humidity and temperature of Ho Chi Minh City are higher than optimal conditions to raise Earthworm. In addition, the percentage of biomass is highest when rising the proportion of food waste and cow dung 4:6, respectively. It’s a point for encourage the applying Earthworm (Perionyx Excavatus) for food waste management in Ho Chi Minh.

WORM BIOMASS AND VERMICOMPOST PRODUCTION BY THE EPIGEIC EARTHWORM, PERIONYX EXCAVATUS BY USING DIFFERENT ORGANIC WASTES

As the epigeic earthworms are known to be efcient and potential biodegrades and nutrient releasers, tolerant to wide range of ecological disturbances, aids in litter communication and efcient decomposers. Therefore, the present study was undertaken to nd out the inuence of various organic wastes (such as False Ashoka waste-FAW (Polyalthia longifolia), Parthenium wastePW (Parthenium hysterophorus), Cotton residue waste-CRW (Gossypium), Lawn grass waste-LGW (Agrostis) and Cattle manure-CM) on the production of worm biomass and vermicompost by the epigeic earthworm, Perionyx excavatus along with control compost experiments without worms (in triplicates) to know the potentiality of this worm species in processing of various organic wastes for the production of worm biomass as vermiprotein and vermicompost as biofertilizer. Both compost and vermicompost experimental pots were terminated after 35 and 70 days time intervals. Observations were made with respect to number of old and new adult worms, new sub-clitellates, juveniles, cocoons with their weight were noted to determine the total worm biomass (Gross biomass), biomass ratio (WBR) and Fold Increase in Worm Number (FIWN). Percent compost and vermicompost produced out of different organic waste were also calculated at the end of each experiment at35 and 70 days. The results of the present study revealed that the biomass of Perionyx excavatus such as Gross worm biomass (GWB), Worm biomass ratio (WBR) and Fold increase in worm number (FIWN) increased from 35days to 70 days time intervals in all the organic wastes (FAW, PW, CRW, LGW and CM). It was maximum in CM and minimum in FAW among all the organic wastes. There is a signicant variation was noticed in worm biomass production (GWB, WBR, and FIWN) among and between all the organic wastes except between few organic wastes at 35 and 70 days time intervals. The vermicompost production was more as compared to normal compost in all the organic wastes. Further, both compost and vermicompost production were more in CM followed by LGW, CRW, PW and minimum in FAW among all organic wastes. The signicant difference was also observed in the production of compost and vermicompost among and between different organic wastes except between few organic wastes at different time intervals. Based on the results, it can be concluded that the earthworm, Perionyx excavatus is an efcient epigeic earthworm species, effectively used in vermicomposting for the production of vermicompost and as well as in vermifarming in the production of worm biomass as vermiprotein. Further, earthworm biomass, compost and vermicompost production primarily depends on nature of organic wastes and secondly on the potentiality of earthworm species used in the experimental studies.

Potentiality of Vermicomposting in the South Pacific Island Countries: A Review

Incorporation of vermin culture in the composting system produces “vermicompost”, an enriched biofertilizer known to improve the physical, chemical, and biological properties of soil. It is applied in granular form and/or in liquid solution (vermiwash), and in both open fields and greenhouses. Vermicompost has been shown to contain plant growth hormones, which stimulate seed germination and improve crop yield, the ‘marketability’ of products, plant physiology, and their ability to fight against disease. In recent years, South Pacific island countries (SPICs) have placed an increasing emphasis on the importance of organic agricultural practices as a means of achieving more sustainable and environmentally friendly farming practices. However, vermiculture is not practiced in South Pacific island countries (SPICs) largely due to the lack of awareness of this type of application. We consider the inclusion of vermiculture in this region as a potential means of achieving sustainable organic agricultural practices. This study represents a systematic review in which we collect relevant information on vermicomposting and analyze the applicability of this practice in the SPICs based on these nations’ physical, socioeconomic, and climatic conditions. The tropical climate of the SPICs means that they meet the combined requirements of a large available biomass for composting and the availability of earthworms. Perionyx excavatus and Pontoscolex corethrurus have been identified as potential native earthworm species for vermicomposting under the conditions of the SPICs. Eisenia fetida, a well-known earthworm species, is also effectively adapted to this region and reported to be an efficient species for commercial vermicomposting. However, as a new input into the local production system, there may be unforeseen barriers in the initial stages, as with other advanced technologies, and the introduction of vermiculture as a practice requires a steady effort and adaptive research to achieve success. Further experimental research is required to analyze the productivity and profitability of using the identified native earthworm species for vermiculture using locally available biomass in the SPICs.

Effect of Metal Contamination and Pesticides on the Cellulase-producing Microbes Present in the Gut of Perionyx Excavatus

Cellulase-producing microorganisms were isolated and identified as Micrococcus luteus, Bacillus megaterium and Enterobacter cloacae among the bacteria and P. boydii, Streptomyces sp. and Candida sp. among the fungal isolates from the gut of Perionyx excavatus. They were then subjected to two different doses of metal Zinc ((Dose I- 60mg/Kg and Dose II- 120 mg/Kg.) and two doses of two commonly used pesticides (Pendimethalin and Pretilachlor). It has been observed that out of the six cellulase-producing microbes, the higher dose of the metal was proved to be detrimental for three of them. Bacillus megaterium, that was found to be producing a sufficient amount of the enzyme, was absent even when it has been exposed to the lower dose of the metal. Also, the fungal isolates showed a decrease in number when exposed to higher dose of the contaminants. But the cellulase- producing bacterial isolates like Micrococcus luteus and Enterobacter cloacae were not at all affected by the presence of either metal or the pesticides. The experiment throws light on the microbe-earthworm relationship and effect of toxins and metals on the commercially- important microbes present in the soil and earthworm’s gut. The isolates that were present even at the higher doses of the metal and pesticides would be very promising for the production of large amount of the enzyme cellulase.

Metagenomic Exploration of Bacterial Community Structure of Earthworms’ Gut

Living organisms are naturally bestowed with unique and imitable qualities for maintaining ecological balance and earthworms are no exceptions. These so-called keystone species of terrestrial ecosystems are equipped with wonderful machinery, allowing them to nurture soil beautifully. Earthworm gut represents a potential microbial reservoir, having a complex interdependence with the host. The study aimed to profile bacterial community structure of three earthworm species belonging to two different life forms; Perionyx excavatus and Eudrilus eugeniae (epigeic), Polypheretima elongata (endogeic) respectively. Diversity analysis using 16S amplicon sequencing revealed that the dominant phyla were Proteobacteria (34.17-77.88) followed by Actinobacteria (13.43-35.54%), Firmicutes (1.69-15.45%) and Bacteroidetes (0.51-8.12%). The alpha diversity indices explicit similar gut microbiota of Perionyx excavatus and Eudrilus eugeniae and while higher alpha diversity was recorded in comparison to Polypheretima elongata gut. The taxonomic to the phenotypic annotation of 16S rRNA metagenomes revealed that dominance of Gram-negative bacterial community in all earthworm species while, Polypheretima elongata comprises higher percentage (78%) of Gram-negative bacterial community to Perionyx excavatus (32.3%) and Eudrilus eugeniae (38.3%). The oxygen requirement phenotypic analysis showed that all earthworm species were abundant with aerobic followed by anaerobic bacterial groups. Furthermore, functional metabolism phenotypic analysis revealed that a high abundance of ammonia oxidizers (29.3-80.2%), the gut microbiomes showed the relative abundance of sulphate reducer (22.6-78.7%), nitrite reducer (19.8-73.2%), dehalogenators (12.6-25.1%), illustrating in the role of these microbial communities in various degradation and bioremediation processes. The present study signifies the intrinsic gut microbiota of earthworm species for intensified biodegradation.