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Three isolates viz. Lysinibacillus sp. HT13, Alcaligenes sp. HT15 and Proteus sp. HT37 isolated from fish processing effluent and having a C/N ratio of 2, removed 218, 169, and 400 µg cell(-1) day(-1) NH4(+)-N, respectively without subsequent build up of nitrite or nitrate. Ability of the selected isolates in removing NH4(+)-N, NO2(-)-N, and NO3(-)-N was checked in the presence of four commonly reported and tested effluent carbon sources viz. pyruvate, glycerol, methanol, and acetate. Further, when supplemented to fish processing wastewater containing 234 ppm total Kjeldahl's nitrogen, Lysinibacillus sp. HT13, Alcaligenes sp. HT15, and Proteus sp. HT37 could remediate 95.74, 86.17, and 76.6% nitrogen, respectively in 48 h. This is the first report of a Lysinibacillus sp. carrying out aerobically the process of simultaneous nitrification and denitrification. The results demonstrate the potential of the isolates for use in treatment of fish processing effluents and demonstrating the efficient removal of ammonia.

A novel estuarine bacterial strain, Solibacillus silvestris AM1, produces an extracellular, thermostable and fibrous, glycoprotein bioemulsifier (BE-AM1). The amyloid nature of the bioemulsifier (BE-AM1) was confirmed by biophysical techniques (Congo red based polarization microscopy, ThioflavinS based fluorescent microscopy, fibrous arrangement in transmission electron microscopy and secondary structure measurement by FTIR and CD spectrum analysis). Cell-bound BE-AM1 production by S. silvestris AM1 during the mid-logarithmic phase of growth coincided with a decrease in cell surface hydrophobicity, and an increase in cell autoaggregation and biofilm formation. It was observed that the total interfacial interaction energy ([Formula: see text]) for the surface of the bioemulsifier producing S. silvestris AM1 and different derivatized surfaces of polystyrene (silanized and sulfonated) was found to support biofilm formation. This study has revealed that the BE-AM1, a bacterial bioemulsifier, is a functional amyloid and has a role in biofilm formation and cell surface modulation in S. silvestris AM1.

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Solibacillus silvestris AM1 was the first strain from the genus to be reported for the production of a functional amyloid and its potential use as a surface active agent, a thermostable glycoprotein amyloid bioemulsifier BE-AM1 capable of influencing environment and biofilm formation. Phylogenetic analysis based on 16S rRNA gene, molecular characterization studies on the basis of DNA-DNA hybridization and chemotaxonomic fatty acid methyl ester (FAME) analysis showed that S. silvestris AM1 as a strain matches with the type strain S. silvestris HR3-23. But strain AM1 differs from the type strain HR3-23 in carbon substrate utilization studies along with amyloid bioemulsifier production ability with potential industrial and environmental applications. S. silvestris AM1 exhibited bioemulsifier production at wide range of factors like pH and NaCl concentrations, while temperature influenced the bioemulsifier production indirectly (since it affected the growth). Bioemulsifier production was observed even at oligotrophic conditions (0.5 mg ml ) seen usually in its native environment. In this study, we have characterized the amyloid producing S. silvestris AM1 taxonomically and also analyzed 16S rDNA of 103 sequences of Solibacillus sp. available, which indicated the possibility of new species in this genus and can be studied for industrially and environmentally important biomolecules.

Isolates were obtained from intertidal zone site samples from all five western and one eastern coastal states of India and were screened. These ecophysiological groups of aerobic, mesophilic, heterotrophic, sporulating, and bioemulsifier-producing bacteria were from Planococcaceae and Bacillaceae. This is the first report of bioemulsifier production by Sporosarcina spp., Lysinibacillus spp., B. thuringiensis, and B. flexus. In this group, Solibacillus silvestris AM1 was found to produce the highest emulsification activity (62.5 %EI) and the sample that yielded it was used to isolate the ecophysiological group of non-bioemulsifier-producing, hydrocarbon-degrading bacteria (belonging to Chromatiales and Bacillales). These yielded hitherto unreported degrader, Rheinheimera sp. CO6 which was selected for the interaction studies (in a microcosm) with bioemulsifier-producing S. silvestris AM1. The gas chromatographic study of these microcosm experiments revealed increased degradation of benzene, toluene, and xylene (BTX) and the growth of Rheinheimera sp. CO6 in the presence of bioemulsifier produced by S. silvestris AM1. Enhancement of the growth of S. silvestris AM1 in the presence of Rheinheimera sp. CO6 was observed possibly due to reduced toxicity of BTX suggesting mutualistic association between the two. This study elucidates the presence and interaction between enhancers and degraders in a hydrocarbon-contaminated intertidal zone and contributes to the knowledge during application of the two in remediation processes.

Adaptation of microbial communities to anthropogenic stress has often been shown to involve reduction in diversity and in selective enrichment of species capable of survival. The gut bacterial community of pollution-stressed polychaete Neanthes chilkaensis was studied using cultivation dependent and independent approaches. The possible role of the gut bacteria in remediation of pollutants was also studied. The analysis of clones covering about 90% of the 16S rRNA clone library indicated that the majority of the taxa in the library resemble GenBank entries of aromatichydrocarbon pollutant degraders. Among them Firmicutes and Actinobacteria were dominant. About 84% of the gut isolates were capable of utilizing PAHs as sole carbon sources while 20% of isolates were found to produce biosurfactants. Production of surfactant along with capability to utilize PAH and other pollutants indicate the role of the gut community in alleviating the pollution stress. The results also show the potential source of microorganisms with industrial and environmental application.