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Chlorella vulgaris encapsulated in alginate beads were added into a bioreactor treating synthetic wastewater using Pseudomonas putida. A symbiotic CO2/O2 gas exchange was established between the two microorganisms for photosynthetic aeration of wastewater. During batch operation, glucose removal efficiency in the bioreactor improved from 50% in 12 h without aeration to 100% in 6 h, when the bioreactor was aerated photosynthetically. During continuous operation, the bioreactor was operated at a low hydraulic retention time of 3.3 h at feed concentrations of 250 and 500 mg/L glucose. The removal efficiency at 500 mg/L increased from 73% without aeration to 100% in the presence of immobilized microalgae. The initial microalgae concentration was critical to achieve adequate aeration, and the removal rate increased with increasing microalgae concentration. The highest removal rate of 142 mg/L-h glucose was achieved at an initial microalgae concentration of 190 mg/L. Quantification of microalgae growth in the alginate beads indicated an exponential growth during symbiosis, indicating that the bioreactor performance was limited by oxygen production rates. Under symbiotic conditions, the chlorophyll content of the immobilized microalgae increased by more than 30%. These results indicate that immobilized microalgae in symbiosis with heterotrophic bacteria are promising in wastewater aeration.

Bis(indolyl)methane (BIM) alkaloids are an important group of bioactive natural products predominantly found in marine organisms. Thus, compounds like arsindoline A and B, vibrindole A, arundine, and trisindoline are found in marine bacteria, while the related compound, streptindole is obtained from Streptococcus faecium IB 37, found in human feces. In recent years, these molecules, which display a wide range of biological properties (antibacterial, antiviral, anti-oxidant, neurotoxic activity etc.), have attracted the attention of several synthetic and natural product chemists. This review lists selected bis(indolyl)methane analogues reported from different natural sources to date, together with their biological properties and synthesis. 1 Introduction 2 Occurrence, Isolation, Structure Elucidation, and Biological Activity 3 Synthetic Approaches towards Bis(indolyl)methanes 4 Conclusions Key words bis(indolyl)methanes, natural products, isolation, synthesis, bioactive metabolites P. J. Praveen (left) was born in Kerala, India in 1988; he received his M.Sc. in chemistry in 2010 from the University of Kerala, India. He worked as a Junior Research Fellow at the CSIR-National Chemical Laboratory, Pune till 2013 and then moved to the CSIR-National Institute of Oceanography. Currently, he is studying for a Ph.D. in organic chemistry (working in the area of isolation and synthesis of bioactive marine natural products) under the guidance of Dr. P. S. Parameswaran. P. S. Parameswaran (middle) was born in 1955 in Ernakulam (Kochi), India and received an M.Sc. (applied chemistry) from Kerala University and Ph.D. (topic: chemistry of marine natural products) from Goa University in 1995. He began his career as a lecturer at St Alberts College, Ernakulam in 1979 and later moved to the CSIR-National Institute of Oceanography, Goa as a scientist. Presently, he heads the regional center of the CSIR-NIO in Ernakulam. His research interests include the purification and structure determination of bioactive marine metabolites and the synthesis of heterocyclic compounds using domino and green chemistry techniques. Mahesh S. Majik (right) was born in Goa, India in 1981; he received his M.Sc. in organic chemistry in 2003 from Goa University, India. He worked as a Junior Research Fellow at the CSIR-National Institute of Oceanography, Goa till 2005. He was awarded a Ph.D. degree in organic chemistry (worked in area of domino reactions for natural product synthesis and organocatalyses) under guidance of Prof. Santosh G. Tilve in 2010. Immediately afterward, he started his post-doctoral research in the area of 'the synthesis of modified nucleoside for drug discovery' with the research group of Prof. Lak Shin Jeong at Ewha Womans University, Seoul, South Korea (2010-2012). Then he joined the CSIR-NIO, Goa as a Scientist fellow (QHS) and worked in the field of medicinal chemistry of marine natural products (2012-2014). Since September 2014, he is working as an Assistant Professor at Goa University, Goa, India. His current research interests ...

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