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 approximately 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 responsible 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 influences 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.

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The wood‐feeding termite Coptotermes formosanus represents a unique and impressive system for lignocellulose degradation. The highly efficient digestion of lignocellulose is achieved through symbiosis with gut symbionts like bacteria. Despite extensive research during the last three decades, diversity of bacterial symbionts residing in individual gut regions of the termite and their associated functions is still lacking. To this end, cellulose, xylan, and dye‐decolorization bacteria residing in foregut, midgut, and hindgut regions of C. formosanus were enlisted by using enrichment and culture‐dependent molecular methods. A total of 87 bacterial strains were successfully isolated from different gut regions of C. formosanus which belonged to 27 different species of 10 genera, majorly affiliated with Proteobacteria (80%) and Firmicutes (18.3%). Among the gut regions, 37.9% of the total bacterial isolates were observed in the hindgut that demonstrated predominance of cellulolytic bacteria (47.6%). The majority of the xylanolytic and dye‐decolorization bacteria (50%) were obtained from the foregut and midgut, respectively. Actinobacteria represented by Dietza sp. was observed in the hindgut only. Based on species richness, the highest diversity was observed in midgut and hindgut regions each of which harbored seven unique bacterial species. The members of Enterobacter, Klebsiella, and Pseudomonas were common among the gut regions. The lignocellulolytic activities of the selected potential bacteria signpost their assistance to the host for lignocellulose digestion. The overall results indicate that C. formosanus harbors diverse communities of lignocellulolytic bacteria in different regions of the gut system. These observations will significantly advance our understanding of the termite–bacteria symbiosis and their microbial ecology uniquely existed in different gut regions of C. formosanus, which may further shed a light on its potential values at termite‐modeled biotechnology.

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Background: The synanthropic housefly, Musca domestica, augments the transmission of several detrimental diseases like cholera and avian flu. Consequently, during the last century, many physico-chemical methods including synthetic compounds have been applied for its control. But these methods have proven to be prohibitive due to their side effects and serious issues like resistance development, environmental contamination, and detrimental effects on non-target fauna. Therefore, in view of these objectives, we investigated the effects of bay essential oil (EO) against M. domestica. Methods: The attractant/repellent assays were conducted by double choice technique. Different enzyme assays evaluating the effect of LC 50 concentration of the tested essential oil on larval gut were taken into consideration. To determine the composition, the tested oil was subjected to GC-MS/MS analysis. Further, the morphological alterations caused by EO treatment to third instar larvae were observed in a Nova Nano SEM machine. Data was statistically analyzed by one-way ANOVA using Tukey's test (p < 0.001). The LC 50 and LC 90 values were calculated by probit analysis. Results: The adulticidal bioassay revealed significant effects with LC 50 concentration as 43.03 mg/dm 3 against the newly emerged adult flies while in larvicidal assay mortality was dose dependent showing maximum effect at LC 50 0.0629 μg/cm 2. The pupicidal activity was more effective at a dose of LD 50 64.09 μl/0.25 L of air which either killed the pupae or caused deformity in the emerged adults. Likewise total sugar, protein, glycogen, and lipid contents of larvae were reduced after treatment with EO when compared with the normal larvae along with some gut enzymes. The EO reduced the acetylcholinesterase activity from 0.013 U/mg protein in normal larvae to 0.0093 U/mg protein after EO treatment. The GC-MS/MS analysis of the bay EO showed the abundance of myrcene, linalool, eugenol, chavicol, and anethole along with diterpenoid, geranylgeraniol. However, the insecticidal activity of tested EO might be majorly imparted by eugenol content. The FESEM analysis showed shrinkage of integument and distortion to intersegmental regions caused by the tested compound. Conclusion: The present study concludes the significant efficacy of bay EO against M. domestica which could be employed to breakdown its population below threshold levels to prevent the menace of vector-borne diseases.

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Bioconversion of lignocellulose into renewable energy and commodity products faces a major obstacle of inefficient saccharification due to its recalcitrant structure. In nature, lignocellulose is efficiently degraded by some insects, including termites and beetles, potentially due to the contribution from symbiotic gut bacteria. To this end, the presented investigation reports the isolation and characterization of cellulolytic bacteria from the gut system of red flour beetle, Tribolium castaneum. Out of the 15 isolated bacteria, strain RSP75 showed the highest cellulolytic activities by forming a clearance zone of 28 mm in diameter with a hydrolytic capacity of ~4.7. The MALDI-TOF biotyping and 16S rRNA gene sequencing revealed that the strain RSP75 belongs to Bacillus altitudinis. Among the tested enzymes, B. altitudinis RSP75 showed maximum activity of 63.2 IU/mL extract for xylanase followed by β-glucosidase (47.1 ± 3 IU/mL extract) which were manifold higher than previously reported activities. The highest substrate degradation was achieved with wheat husk and corn cob powder which accounted for 69.2% and 54.5%, respectively. The scanning electron microscopy showed adhesion of the bacterial cells with the substrate which was further substantiated by FTIR analysis that depicted the absence of the characteristic cellulose bands at wave numbers 1247, 1375, and 1735 cm−1 due to hydrolysis by the bacterium. Furthermore, B. altitudinis RSP75 showed co-culturing competence with Saccharomyces cerevisiae for bioethanol production from lignocellulose as revealed by GC-MS analysis. The overall observations signify the gut of T. castaneum as a unique and impressive reservoir to prospect for lignocellulose-degrading bacteria that can have many biotechnological applications, including biofuels and biorefinery.