Total Heterotrophic Bacterial Research Articles

C/N ratio control and substrate addition for periphyton development jointly enhance freshwater prawn Macrobrachium rosenbergii production in ponds

The present research investigated the effect of carbon/nitrogen ratio (C/N ratio) control in ponds with or without substrate addition for periphyton development on production of giant freshwater prawn. C/N ratios of 10, 15 and 20 were investigated in 40 m−2 ponds stocked with 2 prawn juveniles (5.023±0.02 g) m−2 with or without added substrates for periphyton development. The various treatment combinations of C/N ratio and periphyton substrate addition are abbreviated as ‘CN10’, ‘CN15’, ‘CN20’, ‘CN10+P’, ‘CN15+P’ and ‘CN20+P’, P representing periphyton substrate. A locally formulated and prepared feed containing 30% crude protein with C/N ratio10 was applied. Tapioca starch was used as carbohydrate source for manipulating C/N ratio and applied to the water column separately from the feed. Increasing the C/N ratio from 10 to 20 reduced (P<0.001) the total ammonia-nitrogen (TAN), nitrite–nitrogen (NO2–N) and nitrate–nitrogen (NO3–N) in water column and total Kjeldahl nitrogen (TKN) in sediment. The addition of substrates only influenced the NO2–N concentration in the water column (P<0.001). Increasing the C/N ratio raised the total heterotrophic bacterial (THB) population in the water column, sediment and periphyton (P<0.001). It also increased the dry matter (DM), ash free dry matter (AFDM), and chlorophyll a content of periphyton (P<0.001). The lowest specific growth rate (SGR), the highest food conversion ratio (FCR), and the lowest protein efficiency ratio (PER) were recorded in treatment CN10 (P<0.05). The addition of substrates did not influence size at harvest (P>0.05) but improved the survival from 62.8 to 72% (P<0.001). Increasing the C/N ratio from 10 to 20 increased the net yield by 40% and addition of substrate increased the net yield by 23%. The combination of C/N ratio control and substrate addition increased the net yield by 75% from 309 (CN10) to 540 (CN20+P) kg ha−1 (120 days)−1. This 75% higher production concurred with (1) a lower inorganic nitrogen content in the water column, (2) a higher THB abundance supplying additional single cell protein to augment the prawn production, and (3) an improved periphyton productivity and quality.

Biodegradability of grounded cell phone recharge cards in two Niger Delta soils

The biodegradability of four commonly used Global System for Mobile Telecommunication (GSM) telephone recharge cards in rainforest (RS) and mangrove (MS) soils of the Niger Delta were examined. The effect of bio-stimulation with inorganic fertilizers (NPK 15:15;15 and Urea) was also examined. Biodegradation was monitored over 28-day period using changes in total organic carbon (TOC) and carbon dioxide evolution. Positive control consisted of filter paper plus test soil (rain forest soil or mangrove soil). Negative control consisted of recharge card and sterile soil. There was a rapid increase in total heterotrophic bacterial (THB) and fungal (TF) counts from a magnitude of 10 4 to10 7 cfu/g for bacteria ad 10 3 to 10 4 cfu/g for fungi from day 0 to day 28 in the biodegradation test systems in rain forest and mangrove soils. There was no significant difference (p 2 evolution was independent of recharge card, soil type and fertilizer application. It was concluded that GSM recharge cards are readily degraded in both rainforest ad mangrove soils of the Niger Delta, even without bio-stimulation especially when they are first physically broken up. The recharge card type did not influence the rate of biodegradation. Journal of Applied Science, Engineering and Technology Vol. 5(1&2) 2005: 11-20

Risk assessment of heterotrophic bacteria from bottled drinking water sold in Indian markets

One hundred and five samples of bottled drinking water belonging to 30 different brands, collected from six different states of India have been analysed for total heterotrophic bacterial (THB) load and coliforms. Almost all bottlers used multiple treatment procedures such as microfiltration, reverse osmosis and ozonisation to treat the water. Around 40% of the samples exceeded the limit of 100 cfu/ml set by the department of health as well as Bureau of Indian Standards (BIS), Government of India. Fourteen percent and 44% of the samples with THB loads between 100 and 1000 cfu/ml or 1000 cfu/ml tested positive for coliforms indicating a linear relationship between THB and coliform bacteria. Gram-positive genera such as Kurthia and Corynebacterium were found to be dominant genera, while members of the family enterobacteriaceae contributed to 7%. Risk assessment of the heterotrophic bacteria revealed that the majority of the strains acquired resistance against ampicillin, nalidixic acid, novobiocin and oxytetracycline. As bottled drinking water is a ready to drink commodity, the high load of heterotrophic bacteria with multiple drug resistance poses significant health hazards to the consumers, especially to immunocompromised individuals.

Bioremediation of a Petroleum-Hydrocarbon Polluted Agricultural Soil at Various Levels of Soil Tillage in Portharcourt, Nigeria

A combination of field cells involving a control and five treatment cells were evaluated under field conditions in the bioremediation of a petroleum- hydrocarbon polluted agricultural soil over a six-week period. Previous works have indicated that crude oil contamination of soils depletes oxygen reserves in the soils and slows down its diffusion rate to the deeper layers. Hence, this hypothesis was tested in the study by the treatments employed. The treatment option used was the application of mineral fertilizer, and different rates of oxygen exposure through various levels of soil tillage. In the experiments described in this paper, conditions of a major spill were simulated by sprinkling crude oil on the cells using perforated cans. The treatment applications were then resorted to and relevant soil physicochemical characteristics monitored at intervals. The results of the study showed an enormous increase in total heterotrophic bacterial (THB) counts in all the treatment cells. The percentage reduction in total hydrocarbon content (88% to 99%) experienced in the cells that received treatment were significantly different from the control. These results highlight the view that the availability of large amounts of oxygen in the soil profile induces an accelerated biodegradation of petroleum hydrocarbons in a polluted agricultural soil and implies that regular tillage of contaminated soils in the presence of nutrients could achieve the decontamination of such soils.

Biogeochemical processes in the continental slope of Bay of Bengal: I. Bacterial solubilization of inorganic phosphate

Microorganisms play a vital role in the biogeochemical cycles of various marine environments, but studies on occurrence and distribution of such bacteria in the marine environment from India are meager. We studied the phosphate solubilizing property of bacteria from the deep sea sediment of Bay of Bengal, India, to understand their role in phosphorous cycle (and thereby the benthic productivity of the deep sea environment). Sediment samples were obtained from 33 stations between 10 degrees 36'N-20 degrees 01' N and 79 degrees 59' E-87 degrees 30' E along 11 transects at 3 different depths i.e. ca. 200 m, 500 m, 1000 m in each transect. Total heterotrophic bacterial (THB) counts ranged from 0.42 to 37.38 x 10(4) CFU g(-1) dry sediment weight. Of the isolates tested, 7.57% showed the phosphate solubilizing property. The phosphate solubilizing bacterial genera were Pseudomonas, Bacillus, Vibrio, Alcaligenes, Micrococcus, Corynebacterium and Flavobacterium. These strains are good solubilizers of phosphates which ultimately may play a major role in the biogeochemical cycle and the benthic productivity of the Exclusive Economic Zone (EEZ) of Bay of Bengal, because this enzyme is important for the slow, but steady regeneration of phosphate and organic carbon in the deep sea.

The effect of carbohydrate addition on water quality and the nitrogen budget in extensive shrimp culture systems

Water quality and shrimp production were monitored in extensively managed ponds which were fed a 25% (P25) or 40% (P40) dietary protein, each diet complemented with or without carbohydrate (CH) addition. The experiment was carried out in 6-m 3 concrete tanks, with a mud bottom and stocked with 7 post larvae (PL 20) of Penaeus monodon per m 2. Tapioca flour was used as carbohydrate source. CH addition reduced total ammonia nitrogen (TAN) and nitrite–nitrogen (NO 2 −–N) in the water column and TAN in the sediment ( P < 0.001). CH addition also increased the total heterotrophic bacterial (THB) count in water column and sediment ( P < 0.05). Lower specific growth rate (SGR) and higher feed conversion ratio (FCR) were recorded in P25, compared to all other treatments ( P < 0.05). The 160 g m − 2 shrimp yield in treatment P25 + CH was similar to the 157 g m − 2 yield in treatment P40, which was much higher than the 114 g m − 2 yield in treatment P25 ( P < 0.001). CH addition to treatment P40, did not result in a higher yield ( P > 0.05). The protein efficiency ratio (PER) was higher ( P < 0.001) in treatment P25 + CH compared to other treatments. Survival of the shrimps was not affected by treatment ( P > 0.05). A system nitrogen budget revealed that 16% to 21% of the total nitrogen input was retained in the shrimp, 0.22% to 0.49% in the water, 67% to 71% in the sediment, and 2.1% to 2.7% was lost through water exchange. The quantity of nitrogen not retained in shrimp biomass to produce 1 kg of shrimp ranged between 109.2 and 164.0 g N. The total water based N-loss (final pond water N + exchange N-loss) from an extensive type of shrimp culture system was within the range of 2.7% to 3.2% of the total input nitrogen. The percentage non-retained nitrogen was reduced by CH addition ( P < 0.01). In summary, CH addition to the water column under extensive shrimp culture conditions (1) increased the nitrogen retention in harvested shrimp biomass (2) reduced the demand for feed protein (3) reduced the concentration of TAN and NO 2 −–N in the pond, and (4) reduced nitrogen discharge making extensive shrimp farming more ecologically sustainable and economically viable.

Effects of carbohydrate addition on production in extensive shrimp culture systems

One indoor and one on-farm trial were conducted to evaluate the effect of control of carbon/nitrogen ratio (C/N ratio) by addition of carbohydrate to the water column in extensive types of shrimp culture systems. In the indoor experiment, 25% and 40% dietary protein (‘P25’ and ‘P40’) with or without carbohydrate source addition (‘P25+CH’ and ‘P40+CH’) were compared in fiber reinforced plastic tanks of 1200-l capacity stocked with 6 Penaeus monodon juveniles (0.357±0.01 g) m −2. In the on-farm trial, 25% dietary protein with carbohydrate (‘P25+CH’) and 40% dietary protein (‘P40’) were compared in 250-m 2 earthen ponds stocked with 6 post-larvae of P. monodon m −2. Tapioca flour was used as carbohydrate source and applied to the water column followed by the first feeding during the day in both experiments. The addition of carbohydrate significantly ( P<0.001) reduced the total ammonia nitrogen (TAN) in the water and sediment in both experiments. It significantly ( P<0.05) increased the total heterotrophic bacterial (THB) population both in water column and sediment. In the indoor experiments, lower specific growth rate (SGR) and higher feed conversion ratio (FCR) values were recorded in the ‘P25’ treatment compared to shrimps in other treatments ( P<0.05). Higher shrimp yield was recorded in ‘P25+CH’ (64.43 g m −2) when compared to ‘P40’ (44.79 g m −2) ( P<0.001) in the on-farm trial. The FCR value was lower ( P<0.05) in the ‘P25+CH’ treatment than in the ‘P40’ treatment. The nitrogen retention (%) and protein efficiency ratio (PER) were higher ( P<0.001) in the ‘P25+CH’ treatment when compared to other treatments in both experiments. Survival of the shrimps was not affected by treatment ( P>0.05). In the on-farm trial the benefit cost ratio was higher in ‘P25+CH’ treatment than ‘P40’ (1.3 against 0.2) and the profit increased 400% in‘P25+CH’ treatment. A 35% reduction of feed cost and 54% increase in the revenue from shrimp was recorded in the ‘P25+CH’ treatment when compared to the ‘P40’. Control of C/N ratio by the addition of a carbohydrate source to the pond water column benefited the extensive shrimp culture practices in three ways (1) increased heterotrophic bacterial growth supplying bacterial protein to augment the shrimp production, (2) reduced demand for supplemental feed protein and subsequent reduction in feed cost and (3) reduced toxic inorganic nitrogen levels in the pond as well as effluents.

Bioremediation of a crude oil polluted tropical rain forest soil

A combination of options including Biostimulation with agricultural fertilizers, Bioaugumentation and physical processes were evaluated in-situ in the clean-up of crude oil polluted tropical rain forest soil for a period of nine weeks. Soil physicochemical parameters such as moisture (19% to 13%), pH (6.34 to 4.5) and organic carbon (85% to 1.5%) dropped during the remediation treatment. Total Nitrogen increased (0.021% to 0.081%) with increase in period of remediation. There was an increase in the total heterotrophic bacterial (THB) and hydrocarbon utilizing bacterial (HUB) counts in all the remediation options throughout the period. The control site O (no treatment employed) revealed no significant hydrocarbon loss (2%) within the study period. The hydrocarbon losses (73% to 88 %) experienced in five other options were significantly different from the control. Option A (a combination of Biostimulation and Bioaugumentation with indigenous HUB, hot water washing and tilling) recorded a hydrocarbon loss of 83%. Option B (a combination of mixing uncontaminated soil from a different location with polluted soil, tilling and Bioaugumentation with indigenous hydrocarbon utilizing bacteria) produced the lowest level of hydrocarbon loss (73%). Option C (a combination of Biostimulation, Bioaugumentation with indigenous HUB) recorded the highest level of hydrocarbon loss (88%). Option D (a combination of Bioaugumentation with genetically engineered strains of hydrocarbon utilizing Pseudomonas, Biostimulation and tilling) produced a hydrocarbon loss of 82%. Option D1 (a combination of Biostimulation with tilling) produced a hydrocarbon loss of 86%. These results suggest that Biostimulation with tilling (nutrient enhanced in-situ bioremediation) and or the combination ofBiostimulation and Bioaugumentation with indigenous hydrocarbon utilizers would be effective in the remediation of crude oil polluted tropical soils. Key Words: Bioremediation, Bioaugumentation, Biostimulation, Hydrocarbon, Fertilizer [Global Jnl Environ Sci Vol.2(1) 2003: 29-40]