Environmental Surveillance Of Viral Communities In South Indian Brackish Water Ecosystems Using Sybr Green Ii Epifluorescencae Microscopy

Abstract

The infectious viruses constitute a major component of microbial communities and significantly influence ecological processes through host regulation, nutrient recycling, and maintenance of microbial diversity. Brackish water ecosystems represent dynamic environments that may harbor a wide range of viral populations. Despite their ecological and potential public health importance, information on viral abundance in Indian brackish water habitats remains scanty. Therefore, the present investigation was conducted to evaluate the occurrence and abundance of viral communities in selected brackish water ecosystems of Southern India. Water samples were collected from twelve coastal and brackish water-associated locations across Andhra Pradesh and Tamil Nadu. Viral concentrates were obtained by ultrafiltration and subsequently analyzed by epifluorescence microscopy following SYBR Green II staining. Fixed samples were filtered through 0.02 μm Anodisc membranes, stained with fluorescent dye, and examined under ultraviolet excitation using a Carl Zeiss epifluorescence microscope. Virus-like particles (VLPs) were enumerated using ImageJ image analysis software and expressed as particles per mL of water. Viral particles were observed in all investigated samples, confirming the widespread distribution of viral communities in brackish water environments. The abundance of VLPs exhibited substantial variability among sampling locations, ranging from 6.1 × 10² to 7.3 × 10⁷ viruses mL⁻¹. The greatest viral abundance was recorded in samples collected from Bhimavaram, Andhra Pradesh, whereas the lowest concentration was detected in Velankanni, Tamil Nadu. Sites associated with health and aquaculture industry activities generally displayed elevated viral loads, indicating that environmental productivity and host microbial populations may contribute to viral proliferation.

The results highlight the extensive presence and heterogeneous distribution of viral communities within Indian brackish water ecosystems. These findings provide valuable baseline data on environmental viral abundance and emphasize the importance of incorporating viral monitoring into brackish water ecosystem management programs. Furthermore, the study contributes to a better understanding of viral ecology in coastal environments and may support future biosecurity, aquaculture industry, health industry, and environmental surveillance initiatives.