**Gut Microbiome Analysis of Snails: A Biotechnological Approach**

Mudasir A. Dar, Kiran D. Pawar and Radhakrishna S. Pandit

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/68133

#### **Abstract**

Mollusks are a diverse group of animals not only at the species level but also with respect to their habitat and behavior. Gastropods comprise 80% of the mollusks with approxi‐ mately 62,000 living species including snails. Over the period of time, snails have evolved into marine, freshwater and terrestrial forms with a transitional shift in their feeding habits. From prehistoric times, mollusks have established an intimate relationship with humans. These animals are used as food, medicine, offering to gods and are also respon‐ sible for economic losses in the form of agricultural pests. As most of these animals feed on plant biomass, their guts have evolved to digest such lignocellulosic biomass with extraordinary efficiency. The plant fiber digestion in their guts depends predominantly on the metabolic activities of the gastro‐intestinal microflora. Besides digestive functions, the seasonal dynamic and spatial distribution of bacterial gut community largely influ‐ ences cold hardiness and many other metabolic properties in snails. Here, we assessed an overview of the various bacterial populations dwelling in digestive tracts of snails. This chapter provides insights into the gut microbiome of various snails that can be exploited for various industrial applications such as biomass degradation, production of biofuel, paper, wine and laundry detergents.

**Keywords:** Mollusca, snails, gut microbiome, symbiont, bacteria, industrial uses

### **1. Introduction**

The phylum Mollusca is one of the most diverse groups of animals on earth that comprises 50,000 living species. Mollusks are soft‐bodied animals that inhabit almost every kind of habitat. These are dominantly free‐living metazoans that possess a calcareous exoskeleton to provide structural support for a muscular foot and enclose mantle cavity which is generally used for

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feeding, respiration and sometimes locomotion [1]. It constitutes the second largest, and most variable, invertebrate phylum. The living species of the mollusks are divided into seven classes, that is aplacophora, polyplacophora, monoplacophora, gastropoda, cephalopoda, pelecypoda and scaphopoda [2]. Gastropods are the largest group of mollusks, comprising about 80% of the living mollusks with ca. 62,000 living species. The first gastropods originated during the late Cambrian period and over 500 million years ago. Since then, gastropods have radiated into marine, freshwater and terrestrial environments, changing their food preferences from herbivorous to carnivorous, endo‐parasitism or symbiont‐mediated chemoautotrophy [3].

The class gastropoda is the most speciose among animals to inhabit a variety of habitats such as oceans, rivers, etc. and are the ones that have inhabited the land among mollusks [4]. The aquatic forms have adapted to benthic forms while others remained pelagic. The life span ranges from months to decades [5, 6] and in some cases life is marked by varying periods of dormancy [7]. All gastropods are commonly called head‐foot or cephalopodium which is a typical character of all gastropods because the head and foot arise from the same region making it very difficult to differentiate where the head ends or the foot begins [8]. The head of gastropods typically has two or four sensory tentacles with eyes and a ventral large foot, which gives them their name (in Greek, *gaster* is stomach and *poda* is feet). The anterior divi‐ sion of the foot, that is, propodium, is used for crawling. The shell in the larval stage is called protoconch. Most gastropods have a shell that typically opens on the right‐hand side. Several species have operculum that is used to close the shell opening.

Most species of gastropoda include slugs and snails where the snails possess coiled shells on their body. The term snail is often used to describe marine and freshwater snails, along with terrestrial ones. More generally, the term is applied to land snails than to those from the sea or freshwater [9]. Snails generally thrive in habitats rich in calcium, limestone, marl and places with concrete and cement. They are hermaphrodite but reciprocal copulation is required to produce viable eggs. Eggs are laid 8 days after copulation producing about 400 to 1000 eggs per year [10]. Cool and moist soil is necessary for the egg hatching producing juvenile snails that eat their egg shells and remain burrowed for 2 weeks. The juveniles feed on tender shoots of plants while the adult can also digest detritus. Under unfavorable conditions, snails can bury themselves under soil and remain inactive from months to years [11].

The terrestrial snails like *Achatina fulica*, *Achatina achatina* and *Archachatina marginata* are large‐sized terrestrial mollusks that can grow up to 20 cm in length and 10 cm in diameter. In these snails, the brownish shell having dark stripes generally covers half of the body [12]. Among these, the shell of *A. fulica* is smaller that can grow up to 3–4 inches, while *A. achatina* has a larger shell size of 10–11 inches [9].

Snails are both ecologically as well as economically very important animals. In the modern era of technology, the utility of snails is largely neglected, particularly in developed countries. Since snails dwell in a variety of niches, they could harbor a militia of micro‐biota which could be exploited for various biotechnological purposes. This work provides insights into the microbiome of various snails. Furthermore, for the first time, we assessed the probable applications of snails in general and their gut micro‐biota in particular for various biotechnology‐based industries.
