We recorded gregarious flowering of three bamboo species viz. Bambusa arundinacea, Bambusa tulda and Melocanna baccifera during rainy season from early March to late May, 2008 at lowland forest of Bajali area of Indo-...We recorded gregarious flowering of three bamboo species viz. Bambusa arundinacea, Bambusa tulda and Melocanna baccifera during rainy season from early March to late May, 2008 at lowland forest of Bajali area of Indo-Burma hotspot region. A regular method of field sampling of various forest types was used to map the bamboo species in Assam, India. Moreover, people＇s perception on bamboo blooming was investigated at 17 sample plots covering 258 respondents inhabiting at the site at an average of 15 in each plots. A floral clump （inflorescence） emerged and developed into a giant panicle comprising of numerous florets. Two types of seeds viz. bacea and caryopsis were recorded in different species. Viviparous germination was noticed in few bacca seeds produced by M. baccifera and this has unusual occurrence in bamboo. Seed viability test shows that 75% caryopsis seeds were viable; these seeds had the potential of germination and can be used for mass regen- eration. Most local respondents believe that bamboo flowering can result in population explosion of rodent, therefore, they think bamboo flower- ing is positively correlated with famine. This traditional belief results in massive destruction of bamboo clumps, which significantly impacts on rural economy.展开更多
Biosurfactants are biomolecules produced by microorganisms, low in toxicity, biodegradable, and relatively easy to synthesize using renewable waste substrates. Biosurfactants are of great importance with a wide and ve...Biosurfactants are biomolecules produced by microorganisms, low in toxicity, biodegradable, and relatively easy to synthesize using renewable waste substrates. Biosurfactants are of great importance with a wide and versatile range of applications, including the bioremediation of contaminated sites. Plants may accumulate soil potentially toxic elements(PTEs), and the accumulation efficacy may be further enhanced by the biosurfactants produced by rhizospheric microorganisms. Occasionally, the growth of bacteria slows down in adverse conditions, such as highly contaminated soils with PTEs. In this context,the plant's phytoextraction capacity could be improved by the addition of metal-tolerant bacteria that produce biosurfactants. Several sources, categories,and bioavailability of PTEs in soil are reported in this article, with the focus on the cost-effective and sustainable soil remediation technologies, where biosurfactants are used as a remediation method. How rhizobacterial biosurfactants can improve PTE recovery capabilities of plants is discussed, and the molecular mechanisms in bacterial genomes that support the production of important biosurfactants are listed. The status and cost of commercial biosurfactant production in the international market are also presented.展开更多
The environmental influx of hazardous contaminants viz PAHs and HMs occurs due to oil and gas drilling,and processing of petroleum products in industrial facilities and refineries.This problem plagues crude oil drilli...The environmental influx of hazardous contaminants viz PAHs and HMs occurs due to oil and gas drilling,and processing of petroleum products in industrial facilities and refineries.This problem plagues crude oil drilling sites as PAHs are an essential component of and HMs coexist with crude oil.We analyzed the spatial distribution of 16 PAHs and 8 HMs in 10 contaminated sites of Assam,a state in India.These included Digboi,where crude oil was drilled in 1867 and the first oil well in Asia that was drilled.TheƩ16 PAHs in soil were detected with a minimum of 13.48 and a maximum of 86.3 mgkg1 andƩ8 heavy metal concentrations in the soil ranged between 69.51 and 336.06 mgkg1.A negative correlation was detected between the relative concentrations of PAHs and HMs.The results confirmed that the nonbiodegradable nature of HMs made them stay in the soil for longer periods of time.In our study,we found that the levels of lead,copper,nickel,and chromium(total)in soil were 73.62,11.86,58.97 and 158.66 mgkg1.The recovery percentage for PAHs and HMs were in the range of 67e97%and 90e95%respectively.Spatial distribution indices for Phenanthrene/Anthracene,Naphthalene/Acenapthhylene,Chyrsene/Benzo(g,h,i)perylene and Fluranthene/Pyrene)calculated for soil samples indicated that the spatial distribution of PAHs in soil is uneven which might be due to variations in contaminates disseminated in soil.Such regionalized concentration has serious implications on the bio-economy both in terms of health and economy,especially since the proximity of crude oil sites to paddy fields and/or tea plantations uniquely marks the landscape of upper Assam.展开更多
文摘We recorded gregarious flowering of three bamboo species viz. Bambusa arundinacea, Bambusa tulda and Melocanna baccifera during rainy season from early March to late May, 2008 at lowland forest of Bajali area of Indo-Burma hotspot region. A regular method of field sampling of various forest types was used to map the bamboo species in Assam, India. Moreover, people＇s perception on bamboo blooming was investigated at 17 sample plots covering 258 respondents inhabiting at the site at an average of 15 in each plots. A floral clump （inflorescence） emerged and developed into a giant panicle comprising of numerous florets. Two types of seeds viz. bacea and caryopsis were recorded in different species. Viviparous germination was noticed in few bacca seeds produced by M. baccifera and this has unusual occurrence in bamboo. Seed viability test shows that 75% caryopsis seeds were viable; these seeds had the potential of germination and can be used for mass regen- eration. Most local respondents believe that bamboo flowering can result in population explosion of rodent, therefore, they think bamboo flower- ing is positively correlated with famine. This traditional belief results in massive destruction of bamboo clumps, which significantly impacts on rural economy.
基金Dr. Dolikajytoti SHARMA from Gauhati University, India for the technical supportNanda Nath Saikia College, India for supporting this work。
文摘Biosurfactants are biomolecules produced by microorganisms, low in toxicity, biodegradable, and relatively easy to synthesize using renewable waste substrates. Biosurfactants are of great importance with a wide and versatile range of applications, including the bioremediation of contaminated sites. Plants may accumulate soil potentially toxic elements(PTEs), and the accumulation efficacy may be further enhanced by the biosurfactants produced by rhizospheric microorganisms. Occasionally, the growth of bacteria slows down in adverse conditions, such as highly contaminated soils with PTEs. In this context,the plant's phytoextraction capacity could be improved by the addition of metal-tolerant bacteria that produce biosurfactants. Several sources, categories,and bioavailability of PTEs in soil are reported in this article, with the focus on the cost-effective and sustainable soil remediation technologies, where biosurfactants are used as a remediation method. How rhizobacterial biosurfactants can improve PTE recovery capabilities of plants is discussed, and the molecular mechanisms in bacterial genomes that support the production of important biosurfactants are listed. The status and cost of commercial biosurfactant production in the international market are also presented.
基金The authors are grateful to Department of Biotechnology,Government of India for financial support(Grant no.BT/489/NE/TBP/2013 dt 16-4-2014)and to Dolikajyoti Sharma,Gauhati University for technical support.
文摘The environmental influx of hazardous contaminants viz PAHs and HMs occurs due to oil and gas drilling,and processing of petroleum products in industrial facilities and refineries.This problem plagues crude oil drilling sites as PAHs are an essential component of and HMs coexist with crude oil.We analyzed the spatial distribution of 16 PAHs and 8 HMs in 10 contaminated sites of Assam,a state in India.These included Digboi,where crude oil was drilled in 1867 and the first oil well in Asia that was drilled.TheƩ16 PAHs in soil were detected with a minimum of 13.48 and a maximum of 86.3 mgkg1 andƩ8 heavy metal concentrations in the soil ranged between 69.51 and 336.06 mgkg1.A negative correlation was detected between the relative concentrations of PAHs and HMs.The results confirmed that the nonbiodegradable nature of HMs made them stay in the soil for longer periods of time.In our study,we found that the levels of lead,copper,nickel,and chromium(total)in soil were 73.62,11.86,58.97 and 158.66 mgkg1.The recovery percentage for PAHs and HMs were in the range of 67e97%and 90e95%respectively.Spatial distribution indices for Phenanthrene/Anthracene,Naphthalene/Acenapthhylene,Chyrsene/Benzo(g,h,i)perylene and Fluranthene/Pyrene)calculated for soil samples indicated that the spatial distribution of PAHs in soil is uneven which might be due to variations in contaminates disseminated in soil.Such regionalized concentration has serious implications on the bio-economy both in terms of health and economy,especially since the proximity of crude oil sites to paddy fields and/or tea plantations uniquely marks the landscape of upper Assam.
